css: Improve error reporting for variables

Emit errors for all the variables that were being expanded
if an error occurs while parsing a property value at compute time.

Include the variables that are being expanded in the error message.

docs/reference/gtk/css-properties.md

@@ -56,6 +56,30 @@ follows:
 1 value:
 : all
 
+## Custom Properties
+
+GTK supports custom properties as defined in the
+[CSS Custom Properties for Cascading Variables](https://www.w3.org/TR/css-variables-1)
+spec.
+
+Custom properties are defined as follows:
+
+```css
+--prop: red;
+```
+
+and used via the `var` keyword:
+
+```css
+color: var(--prop);
+```
+
+Custom properties can have a fallback for when the referred property is invalid:
+
+```css
+color: var(--prop, green);
+```
+
 ## Colors
 
 GTK extends the CSS syntax with several additional ways to specify colors.

gtk/css/gtkcssparser.c

@@ -26,6 +26,16 @@
 #include "gtkcsserror.h"
 #include "gtkcsslocationprivate.h"
 
+static void clear_ref (GtkCssVariableValueReference *ref);
+
+#define GDK_ARRAY_NAME gtk_css_parser_references
+#define GDK_ARRAY_TYPE_NAME GtkCssParserReferences
+#define GDK_ARRAY_ELEMENT_TYPE GtkCssVariableValueReference
+#define GDK_ARRAY_BY_VALUE 1
+#define GDK_ARRAY_NO_MEMSET 1
+#define GDK_ARRAY_FREE_FUNC clear_ref
+#include "gdk/gdkarrayimpl.c"
+
 typedef struct _GtkCssParserBlock GtkCssParserBlock;
 
 struct _GtkCssParserBlock
@@ -39,7 +49,7 @@ struct _GtkCssParserBlock
 #define GDK_ARRAY_NAME gtk_css_parser_blocks
 #define GDK_ARRAY_TYPE_NAME GtkCssParserBlocks
 #define GDK_ARRAY_ELEMENT_TYPE GtkCssParserBlock
-#define GDK_ARAY_PREALLOC 32
+#define GDK_ARRAY_PREALLOC 32
 #define GDK_ARRAY_NO_MEMSET 1
 #include "gdk/gdkarrayimpl.c"
 
@@ -55,11 +65,53 @@ gtk_css_parser_blocks_drop_last (GtkCssParserBlocks *blocks)
   gtk_css_parser_blocks_set_size (blocks, gtk_css_parser_blocks_get_size (blocks) - 1);
 }
 
+typedef struct _GtkCssTokenizerData GtkCssTokenizerData;
+
+struct _GtkCssTokenizerData
+{
+  GtkCssTokenizer *tokenizer;
+  char *var_name;
+  GtkCssVariableValue *variable;
+};
+
+static void
+gtk_css_tokenizer_data_clear (gpointer data)
+{
+  GtkCssTokenizerData *td = data;
+
+  gtk_css_tokenizer_unref (td->tokenizer);
+  if (td->var_name)
+    g_free (td->var_name);
+  if (td->variable)
+    gtk_css_variable_value_unref (td->variable);
+}
+
+#define GDK_ARRAY_NAME gtk_css_tokenizers
+#define GDK_ARRAY_TYPE_NAME GtkCssTokenizers
+#define GDK_ARRAY_ELEMENT_TYPE GtkCssTokenizerData
+#define GDK_ARRAY_FREE_FUNC gtk_css_tokenizer_data_clear
+#define GDK_ARRAY_BY_VALUE 1
+#define GDK_ARRAY_PREALLOC 16
+#define GDK_ARRAY_NO_MEMSET 1
+#include "gdk/gdkarrayimpl.c"
+
+static inline GtkCssTokenizerData *
+gtk_css_tokenizers_get_last (GtkCssTokenizers *tokenizers)
+{
+  return gtk_css_tokenizers_index (tokenizers, gtk_css_tokenizers_get_size (tokenizers) - 1);
+}
+
+static inline void
+gtk_css_tokenizers_drop_last (GtkCssTokenizers *tokenizers)
+{
+  gtk_css_tokenizers_set_size (tokenizers, gtk_css_tokenizers_get_size (tokenizers) - 1);
+}
+
 struct _GtkCssParser
 {
   volatile int ref_count;
 
-  GtkCssTokenizer *tokenizer;
+  GtkCssTokenizers tokenizers;
   GFile *file;
   GFile *directory;
   GtkCssParserErrorFunc error_func;
@@ -69,10 +121,22 @@ struct _GtkCssParser
   GtkCssParserBlocks blocks;
   GtkCssLocation location;
   GtkCssToken token;
+
+  GtkCssVariableValue **refs;
+  gsize n_refs;
+  gsize next_ref;
+  gboolean var_fallback;
 };
 
+static inline GtkCssTokenizer *
+get_tokenizer (GtkCssParser *self)
+{
+  return gtk_css_tokenizers_get_last (&self->tokenizers)->tokenizer;
+}
+
 static GtkCssParser *
 gtk_css_parser_new (GtkCssTokenizer       *tokenizer,
+                    GtkCssVariableValue   *value,
                     GFile                 *file,
                     GtkCssParserErrorFunc  error_func,
                     gpointer               user_data,
@@ -83,7 +147,14 @@ gtk_css_parser_new (GtkCssTokenizer       *tokenizer,
   self = g_new0 (GtkCssParser, 1);
 
   self->ref_count = 1;
-  self->tokenizer = gtk_css_tokenizer_ref (tokenizer);
+
+  gtk_css_tokenizers_init (&self->tokenizers);
+  gtk_css_tokenizers_append (&self->tokenizers,
+                             &(GtkCssTokenizerData) {
+                               gtk_css_tokenizer_ref (tokenizer),
+                               NULL,
+                               value ? gtk_css_variable_value_ref (value) : NULL });
+
   if (file)
     self->file = g_object_ref (file);
 
@@ -125,21 +196,45 @@ gtk_css_parser_new_for_bytes (GBytes                *bytes,
 {
   GtkCssTokenizer *tokenizer;
   GtkCssParser *result;
-  
+
   tokenizer = gtk_css_tokenizer_new (bytes);
-  result = gtk_css_parser_new (tokenizer, file, error_func, user_data, user_destroy);
+  result = gtk_css_parser_new (tokenizer, NULL, file, error_func, user_data, user_destroy);
   gtk_css_tokenizer_unref (tokenizer);
 
   return result;
 }
 
+GtkCssParser *
+gtk_css_parser_new_for_token_stream (GtkCssVariableValue    *value,
+                                     GFile                  *file,
+                                     GtkCssVariableValue   **refs,
+                                     gsize                   n_refs,
+                                     GtkCssParserErrorFunc   error_func,
+                                     gpointer                user_data,
+                                     GDestroyNotify          user_destroy)
+{
+  GtkCssTokenizer *tokenizer;
+  GtkCssParser *result;
+
+  tokenizer = gtk_css_tokenizer_new_for_range (value->bytes, value->offset,
+                                               value->end_offset - value->offset);
+  result = gtk_css_parser_new (tokenizer, value, file, error_func, user_data, user_destroy);
+  gtk_css_tokenizer_unref (tokenizer);
+
+  result->refs = refs;
+  result->n_refs = n_refs;
+  result->next_ref = 0;
+
+  return result;
+}
+
 static void
 gtk_css_parser_finalize (GtkCssParser *self)
 {
   if (self->user_destroy)
     self->user_destroy (self->user_data);
 
-  g_clear_pointer (&self->tokenizer, gtk_css_tokenizer_unref);
+  gtk_css_tokenizers_clear (&self->tokenizers);
   g_clear_object (&self->file);
   g_clear_object (&self->directory);
   if (gtk_css_parser_blocks_get_size (&self->blocks) > 0)
@@ -179,6 +274,12 @@ gtk_css_parser_get_file (GtkCssParser *self)
   return self->file;
 }
 
+GBytes *
+gtk_css_parser_get_bytes (GtkCssParser *self)
+{
+  return gtk_css_tokenizer_get_bytes (gtk_css_tokenizers_get (&self->tokenizers, 0)->tokenizer);
+}
+
 /**
  * gtk_css_parser_resolve_url:
  * @self: a `GtkCssParser`
@@ -260,7 +361,7 @@ gtk_css_parser_get_start_location (GtkCssParser *self)
 const GtkCssLocation *
 gtk_css_parser_get_end_location (GtkCssParser *self)
 {
-  return gtk_css_tokenizer_get_location (self->tokenizer);
+  return gtk_css_tokenizer_get_location (get_tokenizer (self));
 }
 
 /**
@@ -294,12 +395,14 @@ static void
 gtk_css_parser_ensure_token (GtkCssParser *self)
 {
   GError *error = NULL;
+  GtkCssTokenizer *tokenizer;
 
   if (!gtk_css_token_is (&self->token, GTK_CSS_TOKEN_EOF))
     return;
 
-  self->location = *gtk_css_tokenizer_get_location (self->tokenizer);
-  if (!gtk_css_tokenizer_read_token (self->tokenizer, &self->token, &error))
+  tokenizer = get_tokenizer (self);
+  self->location = *gtk_css_tokenizer_get_location (tokenizer);
+  if (!gtk_css_tokenizer_read_token (tokenizer, &self->token, &error))
     {
       /* We ignore the error here, because the resulting token will
        * likely already trigger an error in the parsing code and
@@ -307,6 +410,49 @@ gtk_css_parser_ensure_token (GtkCssParser *self)
        */
       g_clear_error (&error);
     }
+
+  if (gtk_css_tokenizers_get_size (&self->tokenizers) > 1 && gtk_css_token_is (&self->token, GTK_CSS_TOKEN_EOF))
+    {
+      gtk_css_tokenizers_drop_last (&self->tokenizers);
+      gtk_css_parser_ensure_token (self);
+      return;
+    }
+
+  /* Resolve var(--name): skip it and insert the resolved reference instead */
+  if (self->n_refs > 0 && gtk_css_token_is_function (&self->token, "var") && self->var_fallback == 0)
+    {
+      GtkCssVariableValue *ref;
+      GtkCssTokenizer *ref_tokenizer;
+
+      gtk_css_parser_start_block (self);
+
+      g_assert (gtk_css_parser_has_token (self, GTK_CSS_TOKEN_IDENT));
+
+      char *var_name = gtk_css_parser_consume_ident (self);
+      g_assert (var_name[0] == '-' && var_name[1] == '-');
+
+      /* If we encounter var() in a fallback when we can already resolve the
+       * actual variable, skip it */
+      self->var_fallback++;
+      gtk_css_parser_skip (self);
+      gtk_css_parser_end_block (self);
+      self->var_fallback--;
+
+      g_assert (self->next_ref < self->n_refs);
+
+      ref = self->refs[self->next_ref++];
+      ref_tokenizer = gtk_css_tokenizer_new_for_range (ref->bytes, ref->offset,
+                                                       ref->end_offset - ref->offset);
+      gtk_css_tokenizers_append (&self->tokenizers,
+                                 &(GtkCssTokenizerData) {
+                                   ref_tokenizer,
+                                   g_strdup (var_name),
+                                   gtk_css_variable_value_ref (ref)
+                                 });
+
+      gtk_css_parser_ensure_token (self);
+      g_free (var_name);
+    }
 }
 
 const GtkCssToken *
@@ -523,6 +669,19 @@ gtk_css_parser_skip_until (GtkCssParser    *self,
     }
 }
 
+void
+gtk_css_parser_skip_whitespace (GtkCssParser *self)
+{
+  const GtkCssToken *token;
+
+  for (token = gtk_css_parser_peek_token (self);
+       gtk_css_token_is (token, GTK_CSS_TOKEN_WHITESPACE);
+       token = gtk_css_parser_peek_token (self))
+    {
+      gtk_css_parser_consume_token (self);
+    }
+}
+
 void
 gtk_css_parser_emit_error (GtkCssParser         *self,
                            const GtkCssLocation *start,
@@ -1133,3 +1292,319 @@ gtk_css_parser_consume_any (GtkCssParser            *parser,
 
   return result;
 }
+
+gboolean
+gtk_css_parser_has_references (GtkCssParser *self)
+{
+  GtkCssTokenizer *tokenizer = get_tokenizer (self);
+  gboolean ret = FALSE;
+  int inner_blocks = 0, i;
+
+  gtk_css_tokenizer_save (tokenizer);
+
+  do {
+      const GtkCssToken *token;
+
+      token = gtk_css_parser_get_token (self);
+
+      if (inner_blocks == 0)
+        {
+          if (gtk_css_token_is (token, GTK_CSS_TOKEN_EOF))
+            break;
+
+          if (gtk_css_token_is (token, GTK_CSS_TOKEN_CLOSE_PARENS) ||
+              gtk_css_token_is (token, GTK_CSS_TOKEN_CLOSE_SQUARE))
+            {
+              goto error;
+            }
+        }
+
+      if (gtk_css_token_is_preserved (token, NULL))
+        {
+          if (inner_blocks > 0 && gtk_css_token_is (token, GTK_CSS_TOKEN_EOF))
+            {
+              gtk_css_parser_end_block (self);
+              inner_blocks--;
+            }
+          else
+            {
+              gtk_css_parser_consume_token (self);
+            }
+        }
+      else
+        {
+          gboolean is_var = gtk_css_token_is_function (token, "var");
+
+          inner_blocks++;
+          gtk_css_parser_start_block (self);
+
+          if (!ret && is_var)
+            {
+              token = gtk_css_parser_get_token (self);
+
+              if (gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT))
+                {
+                  const char *var_name = gtk_css_token_get_string (token);
+
+                  if (var_name[0] != '-' || var_name[1] != '-')
+                    goto error;
+
+                  gtk_css_parser_consume_token (self);
+
+                  if (!gtk_css_parser_has_token (self, GTK_CSS_TOKEN_EOF) &&
+                      !gtk_css_parser_has_token (self, GTK_CSS_TOKEN_COMMA))
+                    {
+                      goto error;
+                    }
+
+                  ret = TRUE;
+                }
+            }
+        }
+    }
+  while (!gtk_css_parser_has_token (self, GTK_CSS_TOKEN_SEMICOLON) &&
+         !gtk_css_parser_has_token (self, GTK_CSS_TOKEN_CLOSE_CURLY));
+
+  if (inner_blocks > 0)
+    goto error;
+
+  g_assert (tokenizer == get_tokenizer (self));
+
+  gtk_css_tokenizer_restore (tokenizer);
+  self->location = *gtk_css_tokenizer_get_location (tokenizer);
+  gtk_css_tokenizer_read_token (tokenizer, &self->token, NULL);
+
+  return ret;
+
+error:
+  for (i = 0; i < inner_blocks; i++)
+    gtk_css_parser_end_block (self);
+
+  g_assert (tokenizer == get_tokenizer (self));
+
+  gtk_css_tokenizer_restore (tokenizer);
+  self->location = *gtk_css_tokenizer_get_location (tokenizer);
+  gtk_css_tokenizer_read_token (tokenizer, &self->token, NULL);
+
+  return FALSE;
+}
+
+static void
+clear_ref (GtkCssVariableValueReference *ref)
+{
+  g_free (ref->name);
+  if (ref->fallback)
+    gtk_css_variable_value_unref (ref->fallback);
+}
+
+#define GDK_ARRAY_NAME gtk_css_parser_references
+#define GDK_ARRAY_TYPE_NAME GtkCssParserReferences
+#define GDK_ARRAY_ELEMENT_TYPE GtkCssVariableValueReference
+
+GtkCssVariableValue *
+gtk_css_parser_parse_value_into_token_stream (GtkCssParser *self)
+{
+  GBytes *bytes = gtk_css_tokenizer_get_bytes (get_tokenizer (self));
+  const GtkCssToken *token;
+  gsize offset;
+  gsize length = 0;
+  GtkCssParserReferences refs;
+  int inner_blocks = 0, i;
+  gboolean is_initial = FALSE;
+
+  for (token = gtk_css_parser_peek_token (self);
+       gtk_css_token_is (token, GTK_CSS_TOKEN_WHITESPACE);
+       token = gtk_css_parser_peek_token (self))
+    {
+      gtk_css_parser_consume_token (self);
+    }
+
+  gtk_css_parser_references_init (&refs);
+
+  offset = self->location.bytes;
+
+  do {
+      token = gtk_css_parser_get_token (self);
+
+      if (length == 0 && gtk_css_token_is_ident (token, "initial"))
+        is_initial = TRUE;
+
+      if (gtk_css_token_is (token, GTK_CSS_TOKEN_BAD_STRING) ||
+          gtk_css_token_is (token, GTK_CSS_TOKEN_BAD_URL))
+        {
+          gtk_css_parser_error_syntax (self, "Invalid property value");
+          goto error;
+        }
+
+      if (inner_blocks == 0)
+        {
+          if (gtk_css_token_is (token, GTK_CSS_TOKEN_EOF))
+            break;
+
+          if (gtk_css_token_is (token, GTK_CSS_TOKEN_CLOSE_PARENS) ||
+              gtk_css_token_is (token, GTK_CSS_TOKEN_CLOSE_SQUARE))
+            {
+              gtk_css_parser_error_syntax (self, "Invalid property value");
+              goto error;
+            }
+        }
+
+      if (gtk_css_token_is_preserved (token, NULL))
+        {
+          if (inner_blocks > 0 && gtk_css_token_is (token, GTK_CSS_TOKEN_EOF))
+            {
+              length++;
+              gtk_css_parser_end_block (self);
+
+              inner_blocks--;
+            }
+          else
+            {
+              length++;
+              gtk_css_parser_consume_token (self);
+            }
+        }
+      else
+        {
+          gboolean is_var = gtk_css_token_is_function (token, "var");
+
+          length++;
+          inner_blocks++;
+
+          gtk_css_parser_start_block (self);
+
+          if (is_var)
+            {
+              token = gtk_css_parser_get_token (self);
+
+              if (gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT))
+                {
+                  GtkCssVariableValueReference ref;
+                  char *var_name = g_strdup (gtk_css_token_get_string (token));
+
+                  if (var_name[0] != '-' || var_name[1] != '-')
+                    {
+                      gtk_css_parser_error_value (self, "Invalid variable name: %s", var_name);
+                      g_free (var_name);
+                      goto error;
+                    }
+
+                  length++;
+                  gtk_css_parser_consume_token (self);
+
+                  if (!gtk_css_parser_has_token (self, GTK_CSS_TOKEN_EOF) &&
+                      !gtk_css_parser_has_token (self, GTK_CSS_TOKEN_COMMA))
+                    {
+                      gtk_css_parser_error_syntax (self, "Invalid property value");
+                      g_free (var_name);
+                      goto error;
+                    }
+
+                  ref.name = var_name;
+
+                  if (gtk_css_parser_has_token (self, GTK_CSS_TOKEN_EOF))
+                    {
+                      ref.length = 3;
+                      ref.fallback = NULL;
+                    }
+                  else
+                    {
+                      length++;
+                      gtk_css_parser_consume_token (self);
+
+                      ref.fallback = gtk_css_parser_parse_value_into_token_stream (self);
+
+                      if (ref.fallback == NULL)
+                        {
+                          gtk_css_parser_error_value (self, "Invalid fallback for: %s", var_name);
+                          g_free (var_name);
+                          goto error;
+                        }
+
+                      ref.length = 4 + ref.fallback->length;
+                      length += ref.fallback->length;
+                    }
+
+                  gtk_css_parser_references_append (&refs, &ref);
+                }
+            }
+        }
+    }
+  while (!gtk_css_parser_has_token (self, GTK_CSS_TOKEN_SEMICOLON) &&
+         !gtk_css_parser_has_token (self, GTK_CSS_TOKEN_CLOSE_CURLY));
+
+  if (inner_blocks > 0)
+    {
+      gtk_css_parser_error_syntax (self, "Invalid property value");
+      goto error;
+    }
+
+  if (is_initial && length == 1)
+    {
+      gtk_css_parser_references_clear (&refs);
+
+      return gtk_css_variable_value_new_initial (bytes,
+                                                 offset,
+                                                 self->location.bytes);
+    }
+  else
+    {
+      GtkCssVariableValueReference *out_refs;
+      gsize n_refs;
+
+      n_refs = gtk_css_parser_references_get_size (&refs);
+      out_refs = gtk_css_parser_references_steal (&refs);
+
+      return gtk_css_variable_value_new (bytes,
+                                         offset,
+                                         self->location.bytes,
+                                         length,
+                                         out_refs,
+                                         n_refs);
+    }
+
+error:
+  for (i = 0; i < inner_blocks; i++)
+    gtk_css_parser_end_block (self);
+
+  gtk_css_parser_references_clear (&refs);
+
+  return NULL;
+}
+
+void
+gtk_css_parser_get_expanding_variables (GtkCssParser          *self,
+                                        GtkCssVariableValue ***variables,
+                                        char                ***variable_names,
+                                        gsize                 *n_variables)
+{
+  gsize len = gtk_css_tokenizers_get_size (&self->tokenizers);
+  GtkCssVariableValue **vars = NULL;
+  char **names = NULL;
+  gsize n;
+
+  if (variables)
+    vars = g_new0 (GtkCssVariableValue *, len + 1);
+  if (variable_names)
+    names = g_new0 (char *, len + 1);
+
+  n = 0;
+  for (gsize i = 0; i < gtk_css_tokenizers_get_size (&self->tokenizers); i++)
+    {
+      GtkCssTokenizerData *data = gtk_css_tokenizers_index (&self->tokenizers, i);
+      if (variables && data->variable)
+        vars[n] = gtk_css_variable_value_ref (data->variable);
+      if (variable_names)
+        names[n] = g_strdup (data->var_name);
+      n++;
+    }
+
+  if (variables)
+    *variables = vars;
+
+  if (variable_names)
+    *variable_names = names;
+
+  if (n_variables)
+    *n_variables = n;
+}

gtk/css/gtkcssparserprivate.h

@@ -22,6 +22,7 @@
 
 #include "gtkcssenums.h"
 #include "gtkcsstokenizerprivate.h"
+#include "gtkcssvariablevalueprivate.h"
 
 #include <gio/gio.h>
 
@@ -58,10 +59,18 @@ GtkCssParser *          gtk_css_parser_new_for_bytes            (GBytes
                                                                  GtkCssParserErrorFunc           error_func,
                                                                  gpointer                        user_data,
                                                                  GDestroyNotify                  user_destroy);
+GtkCssParser *          gtk_css_parser_new_for_token_stream     (GtkCssVariableValue            *value,
+                                                                 GFile                          *file,
+                                                                 GtkCssVariableValue           **refs,
+                                                                 gsize                           n_refs,
+                                                                 GtkCssParserErrorFunc           error_func,
+                                                                 gpointer                        user_data,
+                                                                 GDestroyNotify                  user_destroy);
 GtkCssParser *          gtk_css_parser_ref                      (GtkCssParser                   *self);
 void                    gtk_css_parser_unref                    (GtkCssParser                   *self);
 
 GFile *                 gtk_css_parser_get_file                 (GtkCssParser                   *self) G_GNUC_PURE;
+GBytes *                gtk_css_parser_get_bytes                (GtkCssParser                   *self) G_GNUC_PURE;
 GFile *                 gtk_css_parser_resolve_url              (GtkCssParser                   *self,
                                                                  const char                     *url);
 
@@ -81,6 +90,7 @@ void                    gtk_css_parser_end_block                (GtkCssParser
 void                    gtk_css_parser_skip                     (GtkCssParser                   *self);
 void                    gtk_css_parser_skip_until               (GtkCssParser                   *self,
                                                                  GtkCssTokenType                 token_type);
+void                    gtk_css_parser_skip_whitespace          (GtkCssParser                   *self);
 
 void                    gtk_css_parser_emit_error               (GtkCssParser                   *self,
                                                                  const GtkCssLocation           *start,
@@ -150,5 +160,14 @@ gsize                   gtk_css_parser_consume_any              (GtkCssParser
                                                                  gsize                           n_options,
                                                                  gpointer                        user_data);
 
+gboolean                gtk_css_parser_has_references           (GtkCssParser                   *parser);
+
+GtkCssVariableValue *   gtk_css_parser_parse_value_into_token_stream (GtkCssParser              *parser);
+
+void                    gtk_css_parser_get_expanding_variables (GtkCssParser              *parser,
+                                                                GtkCssVariableValue     ***variables,
+                                                                char                    ***names,
+                                                                gsize                     *n_variables);
+
 G_END_DECLS
 

gtk/css/gtkcsssection.c

@@ -26,6 +26,7 @@ struct _GtkCssSection
   int                 ref_count;
   GtkCssSection      *parent;
   GFile              *file;
+  GBytes             *bytes;
   GtkCssLocation      start_location;
   GtkCssLocation      end_location;   /* end location if parser is %NULL */
 };
@@ -48,6 +49,15 @@ GtkCssSection *
 gtk_css_section_new (GFile                *file,
                      const GtkCssLocation *start,
                      const GtkCssLocation *end)
+{
+  return gtk_css_section_new_with_bytes (file, NULL,start, end);
+}
+
+GtkCssSection *
+gtk_css_section_new_with_bytes (GFile  *file,
+                                GBytes *bytes,
+                                const GtkCssLocation *start,
+                                const GtkCssLocation *end)
 {
   GtkCssSection *result;
 
@@ -60,6 +70,8 @@ gtk_css_section_new (GFile                *file,
   result->ref_count = 1;
   if (file)
     result->file = g_object_ref (file);
+  if (bytes)
+    result->bytes = g_bytes_ref (bytes);
   result->start_location = *start;
   result->end_location = *end;
 
@@ -104,6 +116,8 @@ gtk_css_section_unref (GtkCssSection *section)
     gtk_css_section_unref (section->parent);
   if (section->file)
     g_object_unref (section->file);
+  if (section->bytes)
+    g_bytes_unref (section->bytes);
 
   g_free (section);
 }
@@ -151,6 +165,14 @@ gtk_css_section_get_file (const GtkCssSection *section)
   return section->file;
 }
 
+GBytes *
+gtk_css_section_get_bytes (const GtkCssSection *section)
+{
+  g_return_val_if_fail (section != NULL, NULL);
+
+  return section->bytes;
+}
+
 /**
  * gtk_css_section_get_start_location:
  * @section: the section

gtk/css/gtkcsssection.h

@@ -46,6 +46,11 @@ GDK_AVAILABLE_IN_ALL
 GtkCssSection *    gtk_css_section_new                 (GFile                *file,
                                                         const GtkCssLocation *start,
                                                         const GtkCssLocation *end);
+GDK_AVAILABLE_IN_4_16
+GtkCssSection *    gtk_css_section_new_with_bytes      (GFile                *file,
+                                                        GBytes               *bytes,
+                                                        const GtkCssLocation *start,
+                                                        const GtkCssLocation *end);
 GDK_AVAILABLE_IN_ALL
 GtkCssSection *    gtk_css_section_ref                 (GtkCssSection        *section);
 GDK_AVAILABLE_IN_ALL
@@ -61,6 +66,8 @@ GDK_AVAILABLE_IN_ALL
 GtkCssSection *    gtk_css_section_get_parent          (const GtkCssSection  *section);
 GDK_AVAILABLE_IN_ALL
 GFile *            gtk_css_section_get_file            (const GtkCssSection  *section);
+GDK_AVAILABLE_IN_4_16
+GBytes *           gtk_css_section_get_bytes           (const GtkCssSection  *section);
 GDK_AVAILABLE_IN_ALL
 const GtkCssLocation *
                    gtk_css_section_get_start_location  (const GtkCssSection  *section);

gtk/css/gtkcsstokenizer.c

@@ -36,6 +36,9 @@ struct _GtkCssTokenizer
   const char            *end;
 
   GtkCssLocation         position;
+
+  GtkCssLocation         saved_position;
+  const char            *saved_data;
 };
 
 void
@@ -568,6 +571,14 @@ gtk_css_token_init_dimension (GtkCssToken     *token,
 
 GtkCssTokenizer *
 gtk_css_tokenizer_new (GBytes *bytes)
+{
+  return gtk_css_tokenizer_new_for_range (bytes, 0, g_bytes_get_size (bytes));
+}
+
+GtkCssTokenizer *
+gtk_css_tokenizer_new_for_range (GBytes *bytes,
+                                 gsize   offset,
+                                 gsize   length)
 {
   GtkCssTokenizer *tokenizer;
 
@@ -576,8 +587,8 @@ gtk_css_tokenizer_new (GBytes *bytes)
   tokenizer->bytes = g_bytes_ref (bytes);
   tokenizer->name_buffer = g_string_new (NULL);
 
-  tokenizer->data = g_bytes_get_data (bytes, NULL);
-  tokenizer->end = tokenizer->data + g_bytes_get_size (bytes);
+  tokenizer->data = g_bytes_get_region (bytes, 1, offset, length);
+  tokenizer->end = tokenizer->data + length;
 
   gtk_css_location_init (&tokenizer->position);
 
@@ -604,6 +615,12 @@ gtk_css_tokenizer_unref (GtkCssTokenizer *tokenizer)
   g_free (tokenizer);
 }
 
+GBytes *
+gtk_css_tokenizer_get_bytes (GtkCssTokenizer *tokenizer)
+{
+  return tokenizer->bytes;
+}
+
 const GtkCssLocation *
 gtk_css_tokenizer_get_location (GtkCssTokenizer *tokenizer)
 {
@@ -1484,3 +1501,23 @@ gtk_css_tokenizer_read_token (GtkCssTokenizer  *tokenizer,
     }
 }
 
+void
+gtk_css_tokenizer_save (GtkCssTokenizer *tokenizer)
+{
+  g_assert (!tokenizer->saved_data);
+
+  tokenizer->saved_position = tokenizer->position;
+  tokenizer->saved_data = tokenizer->data;
+}
+
+void
+gtk_css_tokenizer_restore (GtkCssTokenizer *tokenizer)
+{
+  g_assert (tokenizer->saved_data);
+
+  tokenizer->position = tokenizer->saved_position;
+  tokenizer->data = tokenizer->saved_data;
+
+  gtk_css_location_init (&tokenizer->saved_position);
+  tokenizer->saved_data = NULL;
+}

gtk/css/gtkcsstokenizerprivate.h

@@ -138,15 +138,22 @@ void                    gtk_css_token_print                     (const GtkCssTok
 char *                  gtk_css_token_to_string                 (const GtkCssToken      *token);
 
 GtkCssTokenizer *       gtk_css_tokenizer_new                   (GBytes                 *bytes);
+GtkCssTokenizer *       gtk_css_tokenizer_new_for_range         (GBytes                 *bytes,
+                                                                 gsize                   offset,
+                                                                 gsize                   length);
 
 GtkCssTokenizer *       gtk_css_tokenizer_ref                   (GtkCssTokenizer        *tokenizer);
 void                    gtk_css_tokenizer_unref                 (GtkCssTokenizer        *tokenizer);
 
+GBytes *                gtk_css_tokenizer_get_bytes             (GtkCssTokenizer        *tokenizer);
 const GtkCssLocation *  gtk_css_tokenizer_get_location          (GtkCssTokenizer        *tokenizer) G_GNUC_CONST;
 
 gboolean                gtk_css_tokenizer_read_token            (GtkCssTokenizer        *tokenizer,
                                                                  GtkCssToken            *token,
                                                                  GError                **error);
 
+void                     gtk_css_tokenizer_save                 (GtkCssTokenizer        *tokenizer);
+void                     gtk_css_tokenizer_restore              (GtkCssTokenizer        *tokenizer);
+
 G_END_DECLS
 

gtk/css/gtkcssvariablevalue.c

@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2023 GNOME Foundation Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alice Mikhaylenko <alicem@gnome.org>
+ */
+
+#include "gtkcssvariablevalueprivate.h"
+
+GtkCssVariableValue *
+gtk_css_variable_value_new (GBytes                       *bytes,
+                            gsize                         offset,
+                            gsize                         end_offset,
+                            gsize                         length,
+                            GtkCssVariableValueReference *references,
+                            gsize                         n_references)
+{
+  GtkCssVariableValue *self = g_new0 (GtkCssVariableValue, 1);
+
+  self->ref_count = 1;
+
+  self->bytes = g_bytes_ref (bytes);
+  self->offset = offset;
+  self->end_offset = end_offset;
+  self->length = length;
+
+  self->references = references;
+  self->n_references = n_references;
+
+  return self;
+}
+
+GtkCssVariableValue *
+gtk_css_variable_value_new_initial (GBytes *bytes,
+                                    gsize   offset,
+                                    gsize   end_offset)
+{
+  GtkCssVariableValue *self = gtk_css_variable_value_new (bytes, offset, end_offset, 1, NULL, 0);
+
+  self->is_invalid = TRUE;
+
+  return self;
+}
+
+GtkCssVariableValue *
+gtk_css_variable_value_ref (GtkCssVariableValue *self)
+{
+  self->ref_count++;
+
+  return self;
+}
+
+void
+gtk_css_variable_value_unref (GtkCssVariableValue *self)
+{
+  gsize i;
+
+  self->ref_count--;
+  if (self->ref_count > 0)
+    return;
+
+  g_bytes_unref (self->bytes);
+
+  for (i = 0; i < self->n_references; i++)
+    {
+      GtkCssVariableValueReference *ref = &self->references[i];
+
+      g_free (ref->name);
+      if (ref->fallback)
+        gtk_css_variable_value_unref (ref->fallback);
+    }
+
+  if (self->section)
+    gtk_css_section_unref (self->section);
+
+  g_free (self->references);
+  g_free (self);
+}
+
+void
+gtk_css_variable_value_print (GtkCssVariableValue *self,
+                              GString             *string)
+{
+  gsize len = self->end_offset - self->offset;
+  gconstpointer data = g_bytes_get_region (self->bytes, 1, self->offset, len);
+
+  g_assert (data != NULL);
+
+  g_string_append_len (string, (const char *) data, len);
+}
+
+char *
+gtk_css_variable_value_to_string (GtkCssVariableValue *self)
+{
+  GString *string = g_string_new (NULL);
+  gtk_css_variable_value_print (self, string);
+  return g_string_free (string, FALSE);
+}
+
+gboolean
+gtk_css_variable_value_equal (const GtkCssVariableValue *value1,
+                              const GtkCssVariableValue *value2)
+{
+  if (value1 == value2)
+    return TRUE;
+
+  if (value1 == NULL || value2 == NULL)
+    return FALSE;
+
+  if (value1->bytes != value2->bytes)
+    return FALSE;
+
+  if (value1->offset != value2->offset)
+    return FALSE;
+
+  if (value1->end_offset != value2->end_offset)
+    return FALSE;
+
+  return TRUE;
+}
+
+GtkCssVariableValue *
+gtk_css_variable_value_transition  (GtkCssVariableValue *start,
+                                    GtkCssVariableValue *end,
+                                    double               progress)
+{
+  GtkCssVariableValue *ret = progress < 0.5 ? start : end;
+
+  if (ret == NULL)
+    return NULL;
+
+  return gtk_css_variable_value_ref (ret);
+}
+
+void
+gtk_css_variable_value_set_section (GtkCssVariableValue *self,
+                                    GtkCssSection       *section)
+{
+  self->section = gtk_css_section_ref (section);
+}
+
+void
+gtk_css_variable_value_taint (GtkCssVariableValue *self)
+{
+  self->is_animation_tainted = TRUE;
+}

gtk/css/gtkcssvariablevalueprivate.h

@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2023 GNOME Foundation Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alice Mikhaylenko <alicem@gnome.org>
+ */
+
+#pragma once
+
+#include "gtkcss.h"
+#include "gtkcsstokenizerprivate.h"
+
+G_BEGIN_DECLS
+
+typedef struct _GtkCssVariableValueReference GtkCssVariableValueReference;
+typedef struct _GtkCssVariableValue GtkCssVariableValue;
+
+struct _GtkCssVariableValueReference
+{
+  char *name;
+  gsize length;
+  GtkCssVariableValue *fallback;
+};
+
+struct _GtkCssVariableValue
+{
+  int ref_count;
+
+  GBytes *bytes;
+  gsize offset;
+  gsize end_offset;
+  gsize length;
+
+  GtkCssVariableValueReference *references;
+  gsize n_references;
+
+  GtkCssSection *section;
+  gboolean is_invalid;
+  gboolean is_animation_tainted;
+};
+
+GtkCssVariableValue *gtk_css_variable_value_new         (GBytes                       *bytes,
+                                                         gsize                         offset,
+                                                         gsize                         end_offset,
+                                                         gsize                         length,
+                                                         GtkCssVariableValueReference *references,
+                                                         gsize                         n_references);
+GtkCssVariableValue *gtk_css_variable_value_new_initial (GBytes                       *bytes,
+                                                         gsize                         offset,
+                                                         gsize                         end_offset);
+GtkCssVariableValue *gtk_css_variable_value_ref         (GtkCssVariableValue          *self);
+void                 gtk_css_variable_value_unref       (GtkCssVariableValue          *self);
+void                 gtk_css_variable_value_print       (GtkCssVariableValue          *self,
+                                                         GString                      *string);
+char *               gtk_css_variable_value_to_string   (GtkCssVariableValue          *self);
+gboolean             gtk_css_variable_value_equal       (const GtkCssVariableValue    *value1,
+                                                         const GtkCssVariableValue    *value2) G_GNUC_PURE;
+GtkCssVariableValue *gtk_css_variable_value_transition  (GtkCssVariableValue          *start,
+                                                         GtkCssVariableValue          *end,
+                                                         double                        progress);
+void                 gtk_css_variable_value_set_section (GtkCssVariableValue          *self,
+                                                         GtkCssSection                *section);
+void                 gtk_css_variable_value_taint       (GtkCssVariableValue          *self);
+
+G_END_DECLS

gtk/css/meson.build

@@ -6,8 +6,9 @@ gtk_css_public_sources = files([
 gtk_css_private_sources = files([
   'gtkcssdataurl.c',
   'gtkcssparser.c',
-  'gtkcsstokenizer.c',
   'gtkcssserializer.c',
+  'gtkcsstokenizer.c',
+  'gtkcssvariablevalue.c',
 ])
 
 gtk_css_public_headers = files([

gtk/gtkcssanimatedstyle.c

@@ -33,13 +33,59 @@
 #include "gtkcssstringvalueprivate.h"
 #include "gtkcssstylepropertyprivate.h"
 #include "gtkcsstransitionprivate.h"
+#include "gtkcssvaluesprivate.h"
 #include "gtkprivate.h"
 #include "gtkstyleanimationprivate.h"
 #include "gtkstylepropertyprivate.h"
 #include "gtkstyleproviderprivate.h"
+#include "gtkcsscustompropertypoolprivate.h"
 
 G_DEFINE_TYPE (GtkCssAnimatedStyle, gtk_css_animated_style, GTK_TYPE_CSS_STYLE)
 
+#define DEFINE_VALUES(ENUM, TYPE, NAME) \
+static inline void \
+gtk_css_ ## NAME ## _values_recompute (GtkCssAnimatedStyle *animated) \
+{ \
+  GtkCssStyle *style = (GtkCssStyle *)animated; \
+  GtkCssValue **values = (GtkCssValue **)((guint8*)(animated->style->NAME) + sizeof (GtkCssValues)); \
+  int i; \
+\
+  for (i = 0; i < G_N_ELEMENTS (NAME ## _props); i++) \
+    { \
+      guint id = NAME ## _props[i]; \
+      GtkCssValue *original, *computed; \
+\
+      if (values[i] == NULL) \
+        continue; \
+\
+      original = gtk_css_style_get_original_value (style, id); \
+      if (original == NULL) \
+        continue; \
+\
+      computed = _gtk_css_value_compute (original, \
+                                         id, \
+                                         animated->provider, \
+                                         style, \
+                                         animated->parent_style, \
+                                         NULL); \
+      if (computed == NULL) \
+        continue; \
+\
+      gtk_css_animated_style_set_animated_value (animated, id, computed); \
+    } \
+}
+
+DEFINE_VALUES (CORE, Core, core)
+DEFINE_VALUES (BACKGROUND, Background, background)
+DEFINE_VALUES (BORDER, Border, border)
+DEFINE_VALUES (ICON, Icon, icon)
+DEFINE_VALUES (OUTLINE, Outline, outline)
+DEFINE_VALUES (FONT, Font, font)
+DEFINE_VALUES (FONT_VARIANT, FontVariant, font_variant)
+DEFINE_VALUES (ANIMATION, Animation, animation)
+DEFINE_VALUES (TRANSITION, Transition, transition)
+DEFINE_VALUES (SIZE, Size, size)
+DEFINE_VALUES (OTHER, Other, other)
 
 static GtkCssSection *
 gtk_css_animated_style_get_section (GtkCssStyle *style,
@@ -74,6 +120,15 @@ gtk_css_animated_style_get_static_style (GtkCssStyle *style)
   return (GtkCssStaticStyle *)animated->style;
 }
 
+static GtkCssValue *
+gtk_css_animated_style_get_original_value (GtkCssStyle *style,
+                                           guint        id)
+{
+  GtkCssAnimatedStyle *animated = GTK_CSS_ANIMATED_STYLE (style);
+
+  return gtk_css_style_get_original_value (animated->style, id);
+}
+
 static void
 gtk_css_animated_style_dispose (GObject *object)
 {
@@ -96,6 +151,9 @@ gtk_css_animated_style_finalize (GObject *object)
   GtkCssAnimatedStyle *style = GTK_CSS_ANIMATED_STYLE (object);
 
   g_object_unref (style->style);
+  if (style->parent_style)
+    g_object_unref (style->parent_style);
+  g_object_unref (style->provider);
 
   G_OBJECT_CLASS (gtk_css_animated_style_parent_class)->finalize (object);
 }
@@ -112,6 +170,7 @@ gtk_css_animated_style_class_init (GtkCssAnimatedStyleClass *klass)
   style_class->get_section = gtk_css_animated_style_get_section;
   style_class->is_static = gtk_css_animated_style_is_static;
   style_class->get_static_style = gtk_css_animated_style_get_static_style;
+  style_class->get_original_value = gtk_css_animated_style_get_original_value;
 }
 
 static void
@@ -546,6 +605,51 @@ gtk_css_animated_style_get_intrinsic_value (GtkCssAnimatedStyle *style,
   return gtk_css_style_get_value (style->style, id);
 }
 
+void
+gtk_css_animated_style_set_animated_custom_value (GtkCssAnimatedStyle *animated,
+                                                  int                  id,
+                                                  GtkCssVariableValue *value)
+{
+  GtkCssStyle *style = (GtkCssStyle *)animated;
+
+  gtk_internal_return_if_fail (GTK_IS_CSS_ANIMATED_STYLE (style));
+  gtk_internal_return_if_fail (value != NULL);
+
+  if (style->variables == NULL)
+    {
+      style->variables = gtk_css_variable_set_new ();
+      if (animated->parent_style)
+        gtk_css_variable_set_set_parent (style->variables,
+                                         animated->parent_style->variables);
+    }
+  else if (style->variables == animated->style->variables)
+    {
+      gtk_css_variable_set_unref (style->variables);
+      style->variables = gtk_css_variable_set_copy (animated->style->variables);
+    }
+
+  gtk_css_variable_set_add (style->variables, id, value);
+
+  gtk_css_core_values_recompute (animated);
+  gtk_css_background_values_recompute (animated);
+  gtk_css_border_values_recompute (animated);
+  gtk_css_icon_values_recompute (animated);
+  gtk_css_outline_values_recompute (animated);
+  gtk_css_font_values_recompute (animated);
+  gtk_css_font_variant_values_recompute (animated);
+  gtk_css_animation_values_recompute (animated);
+  gtk_css_transition_values_recompute (animated);
+  gtk_css_size_values_recompute (animated);
+  gtk_css_other_values_recompute (animated);
+}
+
+GtkCssVariableValue *
+gtk_css_animated_style_get_intrinsic_custom_value (GtkCssAnimatedStyle *style,
+                                                   int                  id)
+{
+  return gtk_css_style_get_custom_property (style->style, id);
+}
+
 static GPtrArray *
 gtk_css_animated_style_create_dynamic (GPtrArray   *animations,
                                        GtkCssStyle *style,
@@ -770,7 +874,6 @@ gtk_css_animated_style_find_animation (GtkStyleAnimation **animations,
 static GPtrArray *
 gtk_css_animated_style_create_css_animations (GPtrArray        *animations,
                                               GtkCssStyle      *base_style,
-                                              GtkCssStyle      *parent_style,
                                               gint64            timestamp,
                                               GtkStyleProvider *provider,
                                               GtkCssStyle      *source)
@@ -832,8 +935,6 @@ gtk_css_animated_style_create_css_animations (GPtrArray        *animations,
           if (keyframes == NULL)
             continue;
 
-          keyframes = _gtk_css_keyframes_compute (keyframes, provider, base_style, parent_style);
-
           animation = _gtk_css_animation_new (name,
                                               keyframes,
                                               timestamp,
@@ -844,7 +945,6 @@ gtk_css_animated_style_create_css_animations (GPtrArray        *animations,
                                               _gtk_css_play_state_value_get (_gtk_css_array_value_get_nth (play_states, i)),
                                               _gtk_css_fill_mode_value_get (_gtk_css_array_value_get_nth (fill_modes, i)),
                                               _gtk_css_number_value_get (_gtk_css_array_value_get_nth (iteration_counts, i), 100));
-          _gtk_css_keyframes_unref (keyframes);
         }
 
       if (!animations)
@@ -893,7 +993,7 @@ gtk_css_animated_style_new (GtkCssStyle      *base_style,
   if (previous_style != NULL)
     animations = gtk_css_animated_style_create_css_transitions (animations, base_style, timestamp, previous_style);
 
-  animations = gtk_css_animated_style_create_css_animations (animations, base_style, parent_style, timestamp, provider, previous_style);
+  animations = gtk_css_animated_style_create_css_animations (animations, base_style, timestamp, provider, previous_style);
   animations = gtk_css_animated_style_create_dynamic (animations, base_style, timestamp);
 
   if (animations == NULL)
@@ -902,6 +1002,9 @@ gtk_css_animated_style_new (GtkCssStyle      *base_style,
   result = g_object_new (GTK_TYPE_CSS_ANIMATED_STYLE, NULL);
 
   result->style = g_object_ref (base_style);
+  if (parent_style)
+    result->parent_style = g_object_ref (parent_style);
+  result->provider = g_object_ref (provider);
   result->current_time = timestamp;
   result->n_animations = animations->len;
   result->animations = g_ptr_array_free (animations, FALSE);
@@ -918,6 +1021,8 @@ gtk_css_animated_style_new (GtkCssStyle      *base_style,
   style->transition = (GtkCssTransitionValues *)gtk_css_values_ref ((GtkCssValues *)base_style->transition);
   style->size = (GtkCssSizeValues *)gtk_css_values_ref ((GtkCssValues *)base_style->size);
   style->other = (GtkCssOtherValues *)gtk_css_values_ref ((GtkCssValues *)base_style->other);
+  if (base_style->variables)
+    style->variables = gtk_css_variable_set_ref (base_style->variables);
 
   gtk_css_animated_style_apply_animations (result);
 
@@ -927,7 +1032,9 @@ gtk_css_animated_style_new (GtkCssStyle      *base_style,
 GtkCssStyle *
 gtk_css_animated_style_new_advance (GtkCssAnimatedStyle *source,
                                     GtkCssStyle         *base_style,
-                                    gint64               timestamp)
+                                    GtkCssStyle         *parent_style,
+                                    gint64               timestamp,
+                                    GtkStyleProvider    *provider)
 {
   GtkCssAnimatedStyle *result;
   GtkCssStyle *style;
@@ -936,6 +1043,8 @@ gtk_css_animated_style_new_advance (GtkCssAnimatedStyle *source,
 
   gtk_internal_return_val_if_fail (GTK_IS_CSS_ANIMATED_STYLE (source), NULL);
   gtk_internal_return_val_if_fail (GTK_IS_CSS_STYLE (base_style), NULL);
+  gtk_internal_return_val_if_fail (parent_style == NULL || GTK_IS_CSS_STYLE (parent_style), NULL);
+  gtk_internal_return_val_if_fail (GTK_IS_STYLE_PROVIDER (provider), NULL);
 
   if (timestamp == 0)
     return g_object_ref (source->style);
@@ -966,6 +1075,9 @@ gtk_css_animated_style_new_advance (GtkCssAnimatedStyle *source,
   result = g_object_new (GTK_TYPE_CSS_ANIMATED_STYLE, NULL);
 
   result->style = g_object_ref (base_style);
+  if (parent_style)
+    result->parent_style = g_object_ref (parent_style);
+  result->provider = g_object_ref (provider);
   result->current_time = timestamp;
   result->n_animations = animations->len;
   result->animations = g_ptr_array_free (animations, FALSE);
@@ -982,8 +1094,34 @@ gtk_css_animated_style_new_advance (GtkCssAnimatedStyle *source,
   style->transition = (GtkCssTransitionValues *)gtk_css_values_ref ((GtkCssValues *)base_style->transition);
   style->size = (GtkCssSizeValues *)gtk_css_values_ref ((GtkCssValues *)base_style->size);
   style->other = (GtkCssOtherValues *)gtk_css_values_ref ((GtkCssValues *)base_style->other);
+  if (base_style->variables)
+    style->variables = gtk_css_variable_set_ref (base_style->variables);
 
   gtk_css_animated_style_apply_animations (result);
 
   return GTK_CSS_STYLE (result);
 }
+
+GtkCssStyle *
+gtk_css_animated_style_get_base_style (GtkCssAnimatedStyle *style)
+{
+  gtk_internal_return_val_if_fail (GTK_IS_CSS_ANIMATED_STYLE (style), NULL);
+
+  return style->style;
+}
+
+GtkCssStyle *
+gtk_css_animated_style_get_parent_style (GtkCssAnimatedStyle *style)
+{
+  gtk_internal_return_val_if_fail (GTK_IS_CSS_ANIMATED_STYLE (style), NULL);
+
+  return style->parent_style;
+}
+
+GtkStyleProvider *
+gtk_css_animated_style_get_provider (GtkCssAnimatedStyle *style)
+{
+  gtk_internal_return_val_if_fail (GTK_IS_CSS_ANIMATED_STYLE (style), NULL);
+
+  return style->provider;
+}

gtk/gtkcssanimatedstyleprivate.h

@@ -38,6 +38,8 @@ struct _GtkCssAnimatedStyle
   GtkCssStyle parent;
 
   GtkCssStyle           *style;                /* the style if we weren't animating */
+  GtkCssStyle           *parent_style;
+  GtkStyleProvider      *provider;
 
   gint64                 current_time;         /* the current time in our world */
   gpointer              *animations;           /* GtkStyleAnimation**, least important one first */
@@ -57,15 +59,26 @@ GtkCssStyle *           gtk_css_animated_style_new              (GtkCssStyle
                                                                  GtkStyleProvider       *provider,
                                                                  GtkCssStyle            *previous_style);
 GtkCssStyle *           gtk_css_animated_style_new_advance      (GtkCssAnimatedStyle    *source,
-                                                                 GtkCssStyle            *base,
-                                                                 gint64                  timestamp);
+                                                                 GtkCssStyle            *base_style,
+                                                                 GtkCssStyle            *parent_style,
+                                                                 gint64                  timestamp,
+                                                                 GtkStyleProvider       *provider);
 
 void                    gtk_css_animated_style_set_animated_value(GtkCssAnimatedStyle   *style,
                                                                  guint                   id,
                                                                  GtkCssValue            *value);
-
 GtkCssValue *           gtk_css_animated_style_get_intrinsic_value (GtkCssAnimatedStyle *style,
                                                                  guint                   id);
 
+void                    gtk_css_animated_style_set_animated_custom_value (GtkCssAnimatedStyle *animated,
+                                                                 int                     id,
+                                                                 GtkCssVariableValue    *value);
+GtkCssVariableValue *   gtk_css_animated_style_get_intrinsic_custom_value (GtkCssAnimatedStyle *style,
+                                                                 int                     id);
+
+GtkCssStyle *           gtk_css_animated_style_get_base_style   (GtkCssAnimatedStyle    *style);
+GtkCssStyle *           gtk_css_animated_style_get_parent_style (GtkCssAnimatedStyle    *style);
+GtkStyleProvider *      gtk_css_animated_style_get_provider     (GtkCssAnimatedStyle    *style);
+
 G_END_DECLS
 

gtk/gtkcssanimation.c

@@ -90,6 +90,9 @@ gtk_css_animation_apply_values (GtkStyleAnimation    *style_animation,
                                 GtkCssAnimatedStyle  *style)
 {
   GtkCssAnimation *animation = (GtkCssAnimation *)style_animation;
+  GtkCssStyle *base_style, *parent_style;
+  GtkStyleProvider *provider;
+  GtkCssKeyframes *resolved_keyframes;
   double progress;
   guint i;
 
@@ -99,19 +102,49 @@ gtk_css_animation_apply_values (GtkStyleAnimation    *style_animation,
   progress = gtk_css_animation_get_progress (animation);
   progress = _gtk_css_ease_value_transform (animation->ease, progress);
 
-  for (i = 0; i < _gtk_css_keyframes_get_n_properties (animation->keyframes); i++)
+  base_style = gtk_css_animated_style_get_base_style (style);
+  parent_style = gtk_css_animated_style_get_parent_style (style);
+  provider = gtk_css_animated_style_get_provider (style);
+  resolved_keyframes = _gtk_css_keyframes_compute (animation->keyframes,
+                                                   provider,
+                                                   base_style,
+                                                   parent_style);
+
+  for (i = 0; i < _gtk_css_keyframes_get_n_variables (resolved_keyframes); i++)
+    {
+      GtkCssVariableValue *value;
+      int variable_id;
+
+      variable_id = _gtk_css_keyframes_get_variable_id (resolved_keyframes, i);
+
+      value = _gtk_css_keyframes_get_variable (resolved_keyframes,
+                                               i,
+                                               progress,
+                                               gtk_css_animated_style_get_intrinsic_custom_value (style, variable_id));
+
+      if (!value)
+        continue;
+
+      gtk_css_animated_style_set_animated_custom_value (style, variable_id, value);
+
+      gtk_css_variable_value_unref (value);
+    }
+
+  for (i = 0; i < _gtk_css_keyframes_get_n_properties (resolved_keyframes); i++)
     {
       GtkCssValue *value;
       guint property_id;
       
-      property_id = _gtk_css_keyframes_get_property_id (animation->keyframes, i);
+      property_id = _gtk_css_keyframes_get_property_id (resolved_keyframes, i);
 
-      value = _gtk_css_keyframes_get_value (animation->keyframes,
+      value = _gtk_css_keyframes_get_value (resolved_keyframes,
                                             i,
                                             progress,
                                             gtk_css_animated_style_get_intrinsic_value (style, property_id));
       gtk_css_animated_style_set_animated_value (style, property_id, value);
     }
+
+  _gtk_css_keyframes_unref (resolved_keyframes);
 }
 
 static gboolean

gtk/gtkcssarrayvalue.c

@@ -41,11 +41,12 @@ gtk_css_value_array_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_array_compute (GtkCssValue      *value,
-                             guint             property_id,
-                             GtkStyleProvider *provider,
-                             GtkCssStyle      *style,
-                             GtkCssStyle      *parent_style)
+gtk_css_value_array_compute (GtkCssValue       *value,
+                             guint              property_id,
+                             GtkStyleProvider  *provider,
+                             GtkCssStyle       *style,
+                             GtkCssStyle       *parent_style,
+                             GtkCssVariableSet *variables)
 {
   GtkCssValue *result;
   GtkCssValue *i_value;
@@ -54,7 +55,7 @@ gtk_css_value_array_compute (GtkCssValue      *value,
   result = NULL;
   for (i = 0; i < value->n_values; i++)
     {
-      i_value =  _gtk_css_value_compute (value->values[i], property_id, provider, style, parent_style);
+      i_value =  _gtk_css_value_compute (value->values[i], property_id, provider, style, parent_style, variables);
 
       if (result == NULL &&
 	  i_value != value->values[i])
@@ -402,10 +403,13 @@ _gtk_css_array_value_new_from_array (GtkCssValue **values,
   for (i = 0; i < n_values; i ++)
     {
       if (!gtk_css_value_is_computed (values[i]))
-        {
-          result->is_computed = FALSE;
-          break;
-        }
+        result->is_computed = FALSE;
+
+      if (gtk_css_value_contains_variables (values[i]))
+        result->contains_variables = TRUE;
+
+      if (!result->is_computed && result->contains_variables)
+        break;
     }
 
   return result;
@@ -467,3 +471,4 @@ _gtk_css_array_value_get_n_values (const GtkCssValue *value)
   return value->n_values;
 }
 
+

gtk/gtkcssbgsizevalue.c

@@ -41,11 +41,12 @@ gtk_css_value_bg_size_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_bg_size_compute (GtkCssValue      *value,
-                               guint             property_id,
-                               GtkStyleProvider *provider,
-                               GtkCssStyle      *style,
-                               GtkCssStyle      *parent_style)
+gtk_css_value_bg_size_compute (GtkCssValue       *value,
+                               guint              property_id,
+                               GtkStyleProvider  *provider,
+                               GtkCssStyle       *style,
+                               GtkCssStyle       *parent_style,
+                               GtkCssVariableSet *variables)
 {
   GtkCssValue *x, *y;
 
@@ -55,10 +56,10 @@ gtk_css_value_bg_size_compute (GtkCssValue      *value,
   x = y = NULL;
 
   if (value->x)
-    x = _gtk_css_value_compute (value->x, property_id, provider, style, parent_style);
+    x = _gtk_css_value_compute (value->x, property_id, provider, style, parent_style, variables);
 
   if (value->y)
-    y = _gtk_css_value_compute (value->y, property_id, provider, style, parent_style);
+    y = _gtk_css_value_compute (value->y, property_id, provider, style, parent_style, variables);
 
   if (x == value->x && y == value->y)
     {
@@ -163,9 +164,9 @@ static const GtkCssValueClass GTK_CSS_VALUE_BG_SIZE = {
   gtk_css_value_bg_size_print
 };
 
-static GtkCssValue auto_singleton = { &GTK_CSS_VALUE_BG_SIZE, 1, TRUE, FALSE, FALSE, NULL, NULL };
-static GtkCssValue cover_singleton = { &GTK_CSS_VALUE_BG_SIZE, 1, TRUE, TRUE, FALSE, NULL, NULL };
-static GtkCssValue contain_singleton = { &GTK_CSS_VALUE_BG_SIZE, 1, TRUE, FALSE, TRUE, NULL, NULL };
+static GtkCssValue auto_singleton = { &GTK_CSS_VALUE_BG_SIZE, 1, TRUE, FALSE, FALSE, FALSE, NULL, NULL };
+static GtkCssValue cover_singleton = { &GTK_CSS_VALUE_BG_SIZE, 1, TRUE, FALSE, TRUE, FALSE, NULL, NULL };
+static GtkCssValue contain_singleton = { &GTK_CSS_VALUE_BG_SIZE, 1, TRUE, FALSE, FALSE, TRUE, NULL, NULL };
 
 GtkCssValue *
 _gtk_css_bg_size_value_new (GtkCssValue *x,

gtk/gtkcssbordervalue.c

@@ -42,11 +42,12 @@ gtk_css_value_border_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_border_compute (GtkCssValue      *value,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_value_border_compute (GtkCssValue       *value,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   GtkCssValue *values[4];
   GtkCssValue *computed;
@@ -57,7 +58,7 @@ gtk_css_value_border_compute (GtkCssValue      *value,
     {
       if (value->values[i])
         {
-          values[i] = _gtk_css_value_compute (value->values[i], property_id, provider, style, parent_style);
+          values[i] = _gtk_css_value_compute (value->values[i], property_id, provider, style, parent_style, variables);
           changed |= (values[i] != value->values[i]);
         }
       else
@@ -260,3 +261,4 @@ _gtk_css_border_value_get_left (const GtkCssValue *value)
   return value->values[GTK_CSS_LEFT];
 }
 
+

gtk/gtkcsscolorvalue.c

@@ -94,10 +94,11 @@ gtk_css_value_color_free (GtkCssValue *color)
 }
 
 static GtkCssValue *
-gtk_css_value_color_get_fallback (guint             property_id,
-                                  GtkStyleProvider *provider,
-                                  GtkCssStyle      *style,
-                                  GtkCssStyle      *parent_style)
+gtk_css_value_color_get_fallback (guint              property_id,
+                                  GtkStyleProvider  *provider,
+                                  GtkCssStyle       *style,
+                                  GtkCssStyle       *parent_style,
+                                  GtkCssVariableSet *variables)
 {
   switch (property_id)
     {
@@ -120,7 +121,8 @@ gtk_css_value_color_get_fallback (guint             property_id,
                                        property_id,
                                        provider,
                                        style,
-                                       parent_style);
+                                       parent_style,
+                                       variables);
       case GTK_CSS_PROPERTY_ICON_PALETTE:
         return _gtk_css_value_ref (style->core->color);
       default:
@@ -132,11 +134,12 @@ gtk_css_value_color_get_fallback (guint             property_id,
 }
 
 static GtkCssValue *
-gtk_css_value_color_compute (GtkCssValue      *value,
-                             guint             property_id,
-                             GtkStyleProvider *provider,
-                             GtkCssStyle      *style,
-                             GtkCssStyle      *parent_style)
+gtk_css_value_color_compute (GtkCssValue       *value,
+                             guint              property_id,
+                             GtkStyleProvider  *provider,
+                             GtkCssStyle       *style,
+                             GtkCssStyle       *parent_style,
+                             GtkCssVariableSet *variables)
 {
   GtkCssValue *resolved;
 
@@ -173,7 +176,7 @@ gtk_css_value_color_compute (GtkCssValue      *value,
     }
 
   if (resolved == NULL)
-    return gtk_css_value_color_get_fallback (property_id, provider, style, parent_style);
+    return gtk_css_value_color_get_fallback (property_id, provider, style, parent_style, variables);
 
   return resolved;
 }
@@ -484,9 +487,9 @@ _gtk_css_color_value_resolve (GtkCssValue      *color,
   return value;
 }
 
-static GtkCssValue transparent_black_singleton = { &GTK_CSS_VALUE_COLOR, 1, TRUE, COLOR_TYPE_LITERAL, NULL,
+static GtkCssValue transparent_black_singleton = { &GTK_CSS_VALUE_COLOR, 1, TRUE, FALSE, COLOR_TYPE_LITERAL, NULL,
                                                    .sym_col.rgba = {0, 0, 0, 0} };
-static GtkCssValue white_singleton             = { &GTK_CSS_VALUE_COLOR, 1, TRUE, COLOR_TYPE_LITERAL, NULL,
+static GtkCssValue white_singleton             = { &GTK_CSS_VALUE_COLOR, 1, TRUE, FALSE, COLOR_TYPE_LITERAL, NULL,
                                                    .sym_col.rgba = {1, 1, 1, 1} };
 
 
@@ -620,7 +623,7 @@ _gtk_css_color_value_new_mix (GtkCssValue *color1,
 GtkCssValue *
 _gtk_css_color_value_new_current_color (void)
 {
-  static GtkCssValue current_color = { &GTK_CSS_VALUE_COLOR, 1, FALSE, COLOR_TYPE_CURRENT_COLOR, NULL, };
+  static GtkCssValue current_color = { &GTK_CSS_VALUE_COLOR, 1, FALSE, FALSE, COLOR_TYPE_CURRENT_COLOR, NULL, };
 
   return _gtk_css_value_ref (&current_color);
 }

gtk/gtkcsscornervalue.c

@@ -37,16 +37,17 @@ gtk_css_value_corner_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_corner_compute (GtkCssValue      *corner,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_value_corner_compute (GtkCssValue       *corner,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   GtkCssValue *x, *y;
 
-  x = _gtk_css_value_compute (corner->x, property_id, provider, style, parent_style);
-  y = _gtk_css_value_compute (corner->y, property_id, provider, style, parent_style);
+  x = _gtk_css_value_compute (corner->x, property_id, provider, style, parent_style, variables);
+  y = _gtk_css_value_compute (corner->y, property_id, provider, style, parent_style, variables);
   if (x == corner->x && y == corner->y)
     {
       _gtk_css_value_unref (x);
@@ -110,14 +111,14 @@ static const GtkCssValueClass GTK_CSS_VALUE_CORNER = {
 };
 
 static GtkCssValue corner_singletons[] = {
-  { &GTK_CSS_VALUE_CORNER, 1, TRUE, NULL, NULL },
-  { &GTK_CSS_VALUE_CORNER, 1, TRUE, NULL, NULL },
-  { &GTK_CSS_VALUE_CORNER, 1, TRUE, NULL, NULL },
-  { &GTK_CSS_VALUE_CORNER, 1, TRUE, NULL, NULL },
-  { &GTK_CSS_VALUE_CORNER, 1, TRUE, NULL, NULL },
-  { &GTK_CSS_VALUE_CORNER, 1, TRUE, NULL, NULL },
-  { &GTK_CSS_VALUE_CORNER, 1, TRUE, NULL, NULL },
-  { &GTK_CSS_VALUE_CORNER, 1, TRUE, NULL, NULL },
+  { &GTK_CSS_VALUE_CORNER, 1, TRUE, FALSE, NULL, NULL },
+  { &GTK_CSS_VALUE_CORNER, 1, TRUE, FALSE, NULL, NULL },
+  { &GTK_CSS_VALUE_CORNER, 1, TRUE, FALSE, NULL, NULL },
+  { &GTK_CSS_VALUE_CORNER, 1, TRUE, FALSE, NULL, NULL },
+  { &GTK_CSS_VALUE_CORNER, 1, TRUE, FALSE, NULL, NULL },
+  { &GTK_CSS_VALUE_CORNER, 1, TRUE, FALSE, NULL, NULL },
+  { &GTK_CSS_VALUE_CORNER, 1, TRUE, FALSE, NULL, NULL },
+  { &GTK_CSS_VALUE_CORNER, 1, TRUE, FALSE, NULL, NULL },
 };
 
 static inline void
@@ -226,3 +227,4 @@ gtk_css_corner_value_is_zero (const GtkCssValue *corner)
   return gtk_css_dimension_value_is_zero (corner->x) &&
          gtk_css_dimension_value_is_zero (corner->y);
 }
+

gtk/gtkcsscustompropertypool.c

@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2023 GNOME Foundation Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alice Mikhaylenko <alicem@gnome.org>
+ */
+
+#include "gtkcsscustompropertypoolprivate.h"
+
+struct _GtkCssCustomPropertyPool
+{
+  GObject parent_instance;
+
+  GArray *names;
+  GHashTable *name_mappings;
+};
+
+struct _GtkCssCustomPropertyName
+{
+  int ref_count;
+  char *name;
+};
+
+typedef struct _GtkCssCustomPropertyName GtkCssCustomPropertyName;
+
+static GtkCssCustomPropertyPool *instance = NULL;
+
+G_DEFINE_FINAL_TYPE (GtkCssCustomPropertyPool, gtk_css_custom_property_pool, G_TYPE_OBJECT)
+
+static void
+clear_custom_property_name (GtkCssCustomPropertyName *name)
+{
+  g_clear_pointer (&name->name, g_free);
+}
+
+static void
+gtk_css_custom_property_pool_finalize (GObject *object)
+{
+  GtkCssCustomPropertyPool *self = (GtkCssCustomPropertyPool *)object;
+
+  g_hash_table_unref (self->name_mappings);
+  g_array_unref (self->names);
+
+  G_OBJECT_CLASS (gtk_css_custom_property_pool_parent_class)->finalize (object);
+}
+
+static void
+gtk_css_custom_property_pool_class_init (GtkCssCustomPropertyPoolClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = gtk_css_custom_property_pool_finalize;
+}
+
+static void
+gtk_css_custom_property_pool_init (GtkCssCustomPropertyPool *self)
+{
+  self->name_mappings = g_hash_table_new (g_str_hash, g_str_equal);
+  self->names = g_array_new (FALSE, FALSE, sizeof (GtkCssCustomPropertyName));
+
+  g_array_set_clear_func (self->names, (GDestroyNotify) clear_custom_property_name);
+}
+
+GtkCssCustomPropertyPool *
+gtk_css_custom_property_pool_get (void)
+{
+  if (instance == NULL)
+    instance = g_object_new (GTK_TYPE_CSS_CUSTOM_PROPERTY_POOL, NULL);
+
+  return instance;
+}
+
+int
+gtk_css_custom_property_pool_add (GtkCssCustomPropertyPool *self,
+                                  const char               *str)
+{
+  GtkCssCustomPropertyName name;
+  int id;
+
+  id = gtk_css_custom_property_pool_lookup (self, str);
+  if (id > 0)
+    return gtk_css_custom_property_pool_ref (self, id);
+
+  name.ref_count = 1;
+  name.name = g_strdup (str);
+
+  // TODO reuse slots after they're gone
+  g_array_append_val (self->names, name);
+
+  id = self->names->len;
+
+  g_hash_table_insert (self->name_mappings, (char *) name.name, GINT_TO_POINTER (id));
+
+  return id;
+}
+
+int
+gtk_css_custom_property_pool_lookup (GtkCssCustomPropertyPool *self,
+                                     const char               *str)
+{
+  gpointer id;
+
+  id = g_hash_table_lookup (self->name_mappings, str);
+
+  return GPOINTER_TO_INT (id);
+}
+
+int
+gtk_css_custom_property_pool_ref (GtkCssCustomPropertyPool *self,
+                                  int                       id)
+{
+  GtkCssCustomPropertyName *name;
+
+  name = &g_array_index (self->names, GtkCssCustomPropertyName, id - 1);
+
+  name->ref_count++;
+
+  return id;
+}
+
+void
+gtk_css_custom_property_pool_unref (GtkCssCustomPropertyPool *self,
+                                    int                       id)
+{
+  GtkCssCustomPropertyName *name;
+
+  name = &g_array_index (self->names, GtkCssCustomPropertyName, id - 1);
+
+  g_assert (name->ref_count > 0);
+
+  name->ref_count--;
+
+  if (name->ref_count == 0)
+    {
+      g_hash_table_remove (self->name_mappings, name->name);
+      clear_custom_property_name (name);
+    }
+}
+
+const char *
+gtk_css_custom_property_pool_get_name (GtkCssCustomPropertyPool *self,
+                                       int                       id)
+{
+  GtkCssCustomPropertyName *name;
+
+  name = &g_array_index (self->names, GtkCssCustomPropertyName, id - 1);
+
+  return name->name;
+}

gtk/gtkcsscustompropertypoolprivate.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2023 GNOME Foundation Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alice Mikhaylenko <alicem@gnome.org>
+ */
+
+#pragma once
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_CSS_CUSTOM_PROPERTY_POOL (gtk_css_custom_property_pool_get_type())
+
+G_DECLARE_FINAL_TYPE (GtkCssCustomPropertyPool, gtk_css_custom_property_pool, GTK, CSS_CUSTOM_PROPERTY_POOL, GObject)
+
+GtkCssCustomPropertyPool *gtk_css_custom_property_pool_get      (void);
+
+int                       gtk_css_custom_property_pool_add      (GtkCssCustomPropertyPool *self,
+                                                                 const char               *str);
+int                       gtk_css_custom_property_pool_lookup   (GtkCssCustomPropertyPool *self,
+                                                                 const char               *str);
+const char *              gtk_css_custom_property_pool_get_name (GtkCssCustomPropertyPool *self,
+                                                                 int                       id);
+int                       gtk_css_custom_property_pool_ref      (GtkCssCustomPropertyPool *self,
+                                                                 int                       id);
+void                      gtk_css_custom_property_pool_unref    (GtkCssCustomPropertyPool *self,
+                                                                 int                       id);
+
+G_END_DECLS

gtk/gtkcsseasevalue.c

@@ -50,11 +50,12 @@ gtk_css_value_ease_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_ease_compute (GtkCssValue      *value,
-                            guint             property_id,
-                            GtkStyleProvider *provider,
-                            GtkCssStyle      *style,
-                            GtkCssStyle      *parent_style)
+gtk_css_value_ease_compute (GtkCssValue       *value,
+                            guint              property_id,
+                            GtkStyleProvider  *provider,
+                            GtkCssStyle       *style,
+                            GtkCssStyle       *parent_style,
+                            GtkCssVariableSet *variables)
 {
   return _gtk_css_value_ref (value);
 }
@@ -407,3 +408,4 @@ _gtk_css_ease_value_transform (const GtkCssValue *ease,
 }
 
 
+

gtk/gtkcssenumvalue.c

@@ -41,11 +41,12 @@ gtk_css_value_enum_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_enum_compute (GtkCssValue      *value,
-                            guint             property_id,
-                            GtkStyleProvider *provider,
-                            GtkCssStyle      *style,
-                            GtkCssStyle      *parent_style)
+gtk_css_value_enum_compute (GtkCssValue       *value,
+                            guint              property_id,
+                            GtkStyleProvider  *provider,
+                            GtkCssStyle       *style,
+                            GtkCssStyle       *parent_style,
+                            GtkCssVariableSet *variables)
 {
   return _gtk_css_value_ref (value);
 }
@@ -87,16 +88,16 @@ static const GtkCssValueClass GTK_CSS_VALUE_BORDER_STYLE = {
 };
 
 static GtkCssValue border_style_values[] = {
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_NONE, "none" },
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_SOLID, "solid" },
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_INSET, "inset" },
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_OUTSET, "outset" },
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_HIDDEN, "hidden" },
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_DOTTED, "dotted" },
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_DASHED, "dashed" },
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_DOUBLE, "double" },
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_GROOVE, "groove" },
-  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, GTK_BORDER_STYLE_RIDGE, "ridge" }
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_NONE, "none" },
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_SOLID, "solid" },
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_INSET, "inset" },
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_OUTSET, "outset" },
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_HIDDEN, "hidden" },
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_DOTTED, "dotted" },
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_DASHED, "dashed" },
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_DOUBLE, "double" },
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_GROOVE, "groove" },
+  { &GTK_CSS_VALUE_BORDER_STYLE, 1, TRUE, FALSE, GTK_BORDER_STYLE_RIDGE, "ridge" }
 };
 
 GtkCssValue *
@@ -145,22 +146,22 @@ static const GtkCssValueClass GTK_CSS_VALUE_BLEND_MODE = {
 };
 
 static GtkCssValue blend_mode_values[] = {
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_DEFAULT, "normal" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_MULTIPLY, "multiply" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_SCREEN, "screen" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_OVERLAY, "overlay" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_DARKEN, "darken" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_LIGHTEN, "lighten" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_COLOR_DODGE, "color-dodge" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_COLOR_BURN, "color-burn" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_HARD_LIGHT, "hard-light" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_SOFT_LIGHT, "soft-light" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_DIFFERENCE, "difference" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_EXCLUSION, "exclusion" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_COLOR, "color" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_HUE, "hue" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_SATURATION, "saturation" },
-  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, GSK_BLEND_MODE_LUMINOSITY, "luminosity" }
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_DEFAULT, "normal" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_MULTIPLY, "multiply" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_SCREEN, "screen" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_OVERLAY, "overlay" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_DARKEN, "darken" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_LIGHTEN, "lighten" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_COLOR_DODGE, "color-dodge" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_COLOR_BURN, "color-burn" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_HARD_LIGHT, "hard-light" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_SOFT_LIGHT, "soft-light" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_DIFFERENCE, "difference" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_EXCLUSION, "exclusion" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_COLOR, "color" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_HUE, "hue" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_SATURATION, "saturation" },
+  { &GTK_CSS_VALUE_BLEND_MODE, 1, TRUE, FALSE, GSK_BLEND_MODE_LUMINOSITY, "luminosity" }
 };
 
 GtkCssValue *
@@ -229,11 +230,12 @@ gtk_css_font_size_get_default_px (GtkStyleProvider *provider,
 }
 
 static GtkCssValue *
-gtk_css_value_font_size_compute (GtkCssValue      *value,
-                                 guint             property_id,
-                                 GtkStyleProvider *provider,
-                                 GtkCssStyle      *style,
-                                 GtkCssStyle      *parent_style)
+gtk_css_value_font_size_compute (GtkCssValue       *value,
+                                 guint              property_id,
+                                 GtkStyleProvider  *provider,
+                                 GtkCssStyle       *style,
+                                 GtkCssStyle       *parent_style,
+                                 GtkCssVariableSet *variables)
 {
   double font_size;
 
@@ -296,15 +298,15 @@ static const GtkCssValueClass GTK_CSS_VALUE_FONT_SIZE = {
 };
 
 static GtkCssValue font_size_values[] = {
-  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, GTK_CSS_FONT_SIZE_SMALLER, "smaller" },
-  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, GTK_CSS_FONT_SIZE_LARGER, "larger" },
-  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, GTK_CSS_FONT_SIZE_XX_SMALL, "xx-small" },
-  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, GTK_CSS_FONT_SIZE_X_SMALL, "x-small" },
-  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, GTK_CSS_FONT_SIZE_SMALL, "small" },
-  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, GTK_CSS_FONT_SIZE_MEDIUM, "medium" },
-  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, GTK_CSS_FONT_SIZE_LARGE, "large" },
-  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, GTK_CSS_FONT_SIZE_X_LARGE, "x-large" },
-  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, GTK_CSS_FONT_SIZE_XX_LARGE, "xx-large" }
+  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, FALSE, GTK_CSS_FONT_SIZE_SMALLER, "smaller" },
+  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, FALSE, GTK_CSS_FONT_SIZE_LARGER, "larger" },
+  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, FALSE, GTK_CSS_FONT_SIZE_XX_SMALL, "xx-small" },
+  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, FALSE, GTK_CSS_FONT_SIZE_X_SMALL, "x-small" },
+  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, FALSE, GTK_CSS_FONT_SIZE_SMALL, "small" },
+  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, FALSE, GTK_CSS_FONT_SIZE_MEDIUM, "medium" },
+  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, FALSE, GTK_CSS_FONT_SIZE_LARGE, "large" },
+  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, FALSE, GTK_CSS_FONT_SIZE_X_LARGE, "x-large" },
+  { &GTK_CSS_VALUE_FONT_SIZE, 1, FALSE, FALSE, GTK_CSS_FONT_SIZE_XX_LARGE, "xx-large" }
 };
 
 GtkCssValue *
@@ -353,9 +355,9 @@ static const GtkCssValueClass GTK_CSS_VALUE_FONT_STYLE = {
 };
 
 static GtkCssValue font_style_values[] = {
-  { &GTK_CSS_VALUE_FONT_STYLE, 1, TRUE, PANGO_STYLE_NORMAL, "normal" },
-  { &GTK_CSS_VALUE_FONT_STYLE, 1, TRUE, PANGO_STYLE_OBLIQUE, "oblique" },
-  { &GTK_CSS_VALUE_FONT_STYLE, 1, TRUE, PANGO_STYLE_ITALIC, "italic" }
+  { &GTK_CSS_VALUE_FONT_STYLE, 1, TRUE, FALSE, PANGO_STYLE_NORMAL, "normal" },
+  { &GTK_CSS_VALUE_FONT_STYLE, 1, TRUE, FALSE, PANGO_STYLE_OBLIQUE, "oblique" },
+  { &GTK_CSS_VALUE_FONT_STYLE, 1, TRUE, FALSE, PANGO_STYLE_ITALIC, "italic" }
 };
 
 GtkCssValue *
@@ -396,11 +398,12 @@ _gtk_css_font_style_value_get (const GtkCssValue *value)
 #define LIGHTER -2
 
 static GtkCssValue *
-gtk_css_value_font_weight_compute (GtkCssValue      *value,
-                                   guint             property_id,
-                                   GtkStyleProvider *provider,
-                                   GtkCssStyle      *style,
-                                   GtkCssStyle      *parent_style)
+gtk_css_value_font_weight_compute (GtkCssValue       *value,
+                                   guint              property_id,
+                                   GtkStyleProvider  *provider,
+                                   GtkCssStyle       *style,
+                                   GtkCssStyle       *parent_style,
+                                   GtkCssVariableSet *variables)
 {
   PangoWeight new_weight;
   int parent_value;
@@ -452,8 +455,8 @@ static const GtkCssValueClass GTK_CSS_VALUE_FONT_WEIGHT = {
 };
 
 static GtkCssValue font_weight_values[] = {
-  { &GTK_CSS_VALUE_FONT_WEIGHT, 1, FALSE, BOLDER, "bolder" },
-  { &GTK_CSS_VALUE_FONT_WEIGHT, 1, FALSE, LIGHTER, "lighter" },
+  { &GTK_CSS_VALUE_FONT_WEIGHT, 1, FALSE, FALSE, BOLDER, "bolder" },
+  { &GTK_CSS_VALUE_FONT_WEIGHT, 1, FALSE, FALSE, LIGHTER, "lighter" },
 };
 
 GtkCssValue *
@@ -502,15 +505,15 @@ static const GtkCssValueClass GTK_CSS_VALUE_FONT_STRETCH = {
 };
 
 static GtkCssValue font_stretch_values[] = {
-  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, PANGO_STRETCH_ULTRA_CONDENSED, "ultra-condensed" },
-  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, PANGO_STRETCH_EXTRA_CONDENSED, "extra-condensed" },
-  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, PANGO_STRETCH_CONDENSED, "condensed" },
-  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, PANGO_STRETCH_SEMI_CONDENSED, "semi-condensed" },
-  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, PANGO_STRETCH_NORMAL, "normal" },
-  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, PANGO_STRETCH_SEMI_EXPANDED, "semi-expanded" },
-  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, PANGO_STRETCH_EXPANDED, "expanded" },
-  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, PANGO_STRETCH_EXTRA_EXPANDED, "extra-expanded" },
-  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, PANGO_STRETCH_ULTRA_EXPANDED, "ultra-expanded" },
+  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, FALSE, PANGO_STRETCH_ULTRA_CONDENSED, "ultra-condensed" },
+  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, FALSE, PANGO_STRETCH_EXTRA_CONDENSED, "extra-condensed" },
+  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, FALSE, PANGO_STRETCH_CONDENSED, "condensed" },
+  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, FALSE, PANGO_STRETCH_SEMI_CONDENSED, "semi-condensed" },
+  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, FALSE, PANGO_STRETCH_NORMAL, "normal" },
+  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, FALSE, PANGO_STRETCH_SEMI_EXPANDED, "semi-expanded" },
+  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, FALSE, PANGO_STRETCH_EXPANDED, "expanded" },
+  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, FALSE, PANGO_STRETCH_EXTRA_EXPANDED, "extra-expanded" },
+  { &GTK_CSS_VALUE_FONT_STRETCH, 1, TRUE, FALSE, PANGO_STRETCH_ULTRA_EXPANDED, "ultra-expanded" },
 };
 
 GtkCssValue *
@@ -559,9 +562,9 @@ static const GtkCssValueClass GTK_CSS_VALUE_TEXT_DECORATION_STYLE = {
 };
 
 static GtkCssValue text_decoration_style_values[] = {
-  { &GTK_CSS_VALUE_TEXT_DECORATION_STYLE, 1, TRUE, GTK_CSS_TEXT_DECORATION_STYLE_SOLID, "solid" },
-  { &GTK_CSS_VALUE_TEXT_DECORATION_STYLE, 1, TRUE, GTK_CSS_TEXT_DECORATION_STYLE_DOUBLE, "double" },
-  { &GTK_CSS_VALUE_TEXT_DECORATION_STYLE, 1, TRUE, GTK_CSS_TEXT_DECORATION_STYLE_WAVY, "wavy" },
+  { &GTK_CSS_VALUE_TEXT_DECORATION_STYLE, 1, TRUE, FALSE, GTK_CSS_TEXT_DECORATION_STYLE_SOLID, "solid" },
+  { &GTK_CSS_VALUE_TEXT_DECORATION_STYLE, 1, TRUE, FALSE, GTK_CSS_TEXT_DECORATION_STYLE_DOUBLE, "double" },
+  { &GTK_CSS_VALUE_TEXT_DECORATION_STYLE, 1, TRUE, FALSE, GTK_CSS_TEXT_DECORATION_STYLE_WAVY, "wavy" },
 };
 
 GtkCssValue *
@@ -610,9 +613,9 @@ static const GtkCssValueClass GTK_CSS_VALUE_AREA = {
 };
 
 static GtkCssValue area_values[] = {
-  { &GTK_CSS_VALUE_AREA, 1, TRUE, GTK_CSS_AREA_BORDER_BOX, "border-box" },
-  { &GTK_CSS_VALUE_AREA, 1, TRUE, GTK_CSS_AREA_PADDING_BOX, "padding-box" },
-  { &GTK_CSS_VALUE_AREA, 1, TRUE, GTK_CSS_AREA_CONTENT_BOX, "content-box" }
+  { &GTK_CSS_VALUE_AREA, 1, TRUE, FALSE, GTK_CSS_AREA_BORDER_BOX, "border-box" },
+  { &GTK_CSS_VALUE_AREA, 1, TRUE, FALSE, GTK_CSS_AREA_PADDING_BOX, "padding-box" },
+  { &GTK_CSS_VALUE_AREA, 1, TRUE, FALSE, GTK_CSS_AREA_CONTENT_BOX, "content-box" }
 };
 
 GtkCssValue *
@@ -667,10 +670,10 @@ static const GtkCssValueClass GTK_CSS_VALUE_DIRECTION = {
 };
 
 static GtkCssValue direction_values[] = {
-  { &GTK_CSS_VALUE_DIRECTION, 1, TRUE, GTK_CSS_DIRECTION_NORMAL, "normal" },
-  { &GTK_CSS_VALUE_DIRECTION, 1, TRUE, GTK_CSS_DIRECTION_REVERSE, "reverse" },
-  { &GTK_CSS_VALUE_DIRECTION, 1, TRUE, GTK_CSS_DIRECTION_ALTERNATE, "alternate" },
-  { &GTK_CSS_VALUE_DIRECTION, 1, TRUE, GTK_CSS_DIRECTION_ALTERNATE_REVERSE, "alternate-reverse" }
+  { &GTK_CSS_VALUE_DIRECTION, 1, TRUE, FALSE, GTK_CSS_DIRECTION_NORMAL, "normal" },
+  { &GTK_CSS_VALUE_DIRECTION, 1, TRUE, FALSE, GTK_CSS_DIRECTION_REVERSE, "reverse" },
+  { &GTK_CSS_VALUE_DIRECTION, 1, TRUE, FALSE, GTK_CSS_DIRECTION_ALTERNATE, "alternate" },
+  { &GTK_CSS_VALUE_DIRECTION, 1, TRUE, FALSE, GTK_CSS_DIRECTION_ALTERNATE_REVERSE, "alternate-reverse" }
 };
 
 GtkCssValue *
@@ -728,8 +731,8 @@ static const GtkCssValueClass GTK_CSS_VALUE_PLAY_STATE = {
 };
 
 static GtkCssValue play_state_values[] = {
-  { &GTK_CSS_VALUE_PLAY_STATE, 1, TRUE, GTK_CSS_PLAY_STATE_RUNNING, "running" },
-  { &GTK_CSS_VALUE_PLAY_STATE, 1, TRUE, GTK_CSS_PLAY_STATE_PAUSED, "paused" }
+  { &GTK_CSS_VALUE_PLAY_STATE, 1, TRUE, FALSE, GTK_CSS_PLAY_STATE_RUNNING, "running" },
+  { &GTK_CSS_VALUE_PLAY_STATE, 1, TRUE, FALSE, GTK_CSS_PLAY_STATE_PAUSED, "paused" }
 };
 
 GtkCssValue *
@@ -784,10 +787,10 @@ static const GtkCssValueClass GTK_CSS_VALUE_FILL_MODE = {
 };
 
 static GtkCssValue fill_mode_values[] = {
-  { &GTK_CSS_VALUE_FILL_MODE, 1, TRUE, GTK_CSS_FILL_NONE, "none" },
-  { &GTK_CSS_VALUE_FILL_MODE, 1, TRUE, GTK_CSS_FILL_FORWARDS, "forwards" },
-  { &GTK_CSS_VALUE_FILL_MODE, 1, TRUE, GTK_CSS_FILL_BACKWARDS, "backwards" },
-  { &GTK_CSS_VALUE_FILL_MODE, 1, TRUE, GTK_CSS_FILL_BOTH, "both" }
+  { &GTK_CSS_VALUE_FILL_MODE, 1, TRUE, FALSE, GTK_CSS_FILL_NONE, "none" },
+  { &GTK_CSS_VALUE_FILL_MODE, 1, TRUE, FALSE, GTK_CSS_FILL_FORWARDS, "forwards" },
+  { &GTK_CSS_VALUE_FILL_MODE, 1, TRUE, FALSE, GTK_CSS_FILL_BACKWARDS, "backwards" },
+  { &GTK_CSS_VALUE_FILL_MODE, 1, TRUE, FALSE, GTK_CSS_FILL_BOTH, "both" }
 };
 
 GtkCssValue *
@@ -842,9 +845,9 @@ static const GtkCssValueClass GTK_CSS_VALUE_ICON_STYLE = {
 };
 
 static GtkCssValue icon_style_values[] = {
-  { &GTK_CSS_VALUE_ICON_STYLE, 1, TRUE, GTK_CSS_ICON_STYLE_REQUESTED, "requested" },
-  { &GTK_CSS_VALUE_ICON_STYLE, 1, TRUE, GTK_CSS_ICON_STYLE_REGULAR, "regular" },
-  { &GTK_CSS_VALUE_ICON_STYLE, 1, TRUE, GTK_CSS_ICON_STYLE_SYMBOLIC, "symbolic" }
+  { &GTK_CSS_VALUE_ICON_STYLE, 1, TRUE, FALSE, GTK_CSS_ICON_STYLE_REQUESTED, "requested" },
+  { &GTK_CSS_VALUE_ICON_STYLE, 1, TRUE, FALSE, GTK_CSS_ICON_STYLE_REGULAR, "regular" },
+  { &GTK_CSS_VALUE_ICON_STYLE, 1, TRUE, FALSE, GTK_CSS_ICON_STYLE_SYMBOLIC, "symbolic" }
 };
 
 GtkCssValue *
@@ -899,9 +902,9 @@ static const GtkCssValueClass GTK_CSS_VALUE_FONT_KERNING = {
 };
 
 static GtkCssValue font_kerning_values[] = {
-  { &GTK_CSS_VALUE_FONT_KERNING, 1, TRUE, GTK_CSS_FONT_KERNING_AUTO, "auto" },
-  { &GTK_CSS_VALUE_FONT_KERNING, 1, TRUE, GTK_CSS_FONT_KERNING_NORMAL, "normal" },
-  { &GTK_CSS_VALUE_FONT_KERNING, 1, TRUE, GTK_CSS_FONT_KERNING_NONE, "none" }
+  { &GTK_CSS_VALUE_FONT_KERNING, 1, TRUE, FALSE, GTK_CSS_FONT_KERNING_AUTO, "auto" },
+  { &GTK_CSS_VALUE_FONT_KERNING, 1, TRUE, FALSE, GTK_CSS_FONT_KERNING_NORMAL, "normal" },
+  { &GTK_CSS_VALUE_FONT_KERNING, 1, TRUE, FALSE, GTK_CSS_FONT_KERNING_NONE, "none" }
 };
 
 GtkCssValue *
@@ -956,9 +959,9 @@ static const GtkCssValueClass GTK_CSS_VALUE_FONT_VARIANT_POSITION = {
 };
 
 static GtkCssValue font_variant_position_values[] = {
-  { &GTK_CSS_VALUE_FONT_VARIANT_POSITION, 1, TRUE, GTK_CSS_FONT_VARIANT_POSITION_NORMAL, "normal" },
-  { &GTK_CSS_VALUE_FONT_VARIANT_POSITION, 1, TRUE, GTK_CSS_FONT_VARIANT_POSITION_SUB, "sub" },
-  { &GTK_CSS_VALUE_FONT_VARIANT_POSITION, 1, TRUE, GTK_CSS_FONT_VARIANT_POSITION_SUPER, "super" }
+  { &GTK_CSS_VALUE_FONT_VARIANT_POSITION, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_POSITION_NORMAL, "normal" },
+  { &GTK_CSS_VALUE_FONT_VARIANT_POSITION, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_POSITION_SUB, "sub" },
+  { &GTK_CSS_VALUE_FONT_VARIANT_POSITION, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_POSITION_SUPER, "super" }
 };
 
 GtkCssValue *
@@ -1013,13 +1016,13 @@ static const GtkCssValueClass GTK_CSS_VALUE_FONT_VARIANT_CAPS = {
 };
 
 static GtkCssValue font_variant_caps_values[] = {
-  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, GTK_CSS_FONT_VARIANT_CAPS_NORMAL, "normal" },
-  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, GTK_CSS_FONT_VARIANT_CAPS_SMALL_CAPS, "small-caps" },
-  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, GTK_CSS_FONT_VARIANT_CAPS_ALL_SMALL_CAPS, "all-small-caps" },
-  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, GTK_CSS_FONT_VARIANT_CAPS_PETITE_CAPS, "petite-caps" },
-  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, GTK_CSS_FONT_VARIANT_CAPS_ALL_PETITE_CAPS, "all-petite-caps" },
-  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, GTK_CSS_FONT_VARIANT_CAPS_UNICASE, "unicase" },
-  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, GTK_CSS_FONT_VARIANT_CAPS_TITLING_CAPS, "titling-caps" }
+  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_CAPS_NORMAL, "normal" },
+  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_CAPS_SMALL_CAPS, "small-caps" },
+  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_CAPS_ALL_SMALL_CAPS, "all-small-caps" },
+  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_CAPS_PETITE_CAPS, "petite-caps" },
+  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_CAPS_ALL_PETITE_CAPS, "all-petite-caps" },
+  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_CAPS_UNICASE, "unicase" },
+  { &GTK_CSS_VALUE_FONT_VARIANT_CAPS, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_CAPS_TITLING_CAPS, "titling-caps" }
 };
 
 GtkCssValue *
@@ -1074,8 +1077,8 @@ static const GtkCssValueClass GTK_CSS_VALUE_FONT_VARIANT_ALTERNATE = {
 };
 
 static GtkCssValue font_variant_alternate_values[] = {
-  { &GTK_CSS_VALUE_FONT_VARIANT_ALTERNATE, 1, TRUE, GTK_CSS_FONT_VARIANT_ALTERNATE_NORMAL, "normal" },
-  { &GTK_CSS_VALUE_FONT_VARIANT_ALTERNATE, 1, TRUE, GTK_CSS_FONT_VARIANT_ALTERNATE_HISTORICAL_FORMS, "historical-forms" }
+  { &GTK_CSS_VALUE_FONT_VARIANT_ALTERNATE, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_ALTERNATE_NORMAL, "normal" },
+  { &GTK_CSS_VALUE_FONT_VARIANT_ALTERNATE, 1, TRUE, FALSE, GTK_CSS_FONT_VARIANT_ALTERNATE_HISTORICAL_FORMS, "historical-forms" }
 };
 
 GtkCssValue *
@@ -1583,10 +1586,10 @@ static const GtkCssValueClass GTK_CSS_VALUE_TEXT_TRANSFORM = {
 };
 
 static GtkCssValue text_transform_values[] = {
-  { &GTK_CSS_VALUE_TEXT_TRANSFORM, 1, TRUE, GTK_CSS_TEXT_TRANSFORM_NONE, "none" },
-  { &GTK_CSS_VALUE_TEXT_TRANSFORM, 1, TRUE, GTK_CSS_TEXT_TRANSFORM_LOWERCASE, "lowercase" },
-  { &GTK_CSS_VALUE_TEXT_TRANSFORM, 1, TRUE, GTK_CSS_TEXT_TRANSFORM_UPPERCASE, "uppercase" },
-  { &GTK_CSS_VALUE_TEXT_TRANSFORM, 1, TRUE, GTK_CSS_TEXT_TRANSFORM_CAPITALIZE, "capitalize" },
+  { &GTK_CSS_VALUE_TEXT_TRANSFORM, 1, TRUE, FALSE, GTK_CSS_TEXT_TRANSFORM_NONE, "none" },
+  { &GTK_CSS_VALUE_TEXT_TRANSFORM, 1, TRUE, FALSE, GTK_CSS_TEXT_TRANSFORM_LOWERCASE, "lowercase" },
+  { &GTK_CSS_VALUE_TEXT_TRANSFORM, 1, TRUE, FALSE, GTK_CSS_TEXT_TRANSFORM_UPPERCASE, "uppercase" },
+  { &GTK_CSS_VALUE_TEXT_TRANSFORM, 1, TRUE, FALSE, GTK_CSS_TEXT_TRANSFORM_CAPITALIZE, "capitalize" },
 };
 
 GtkCssValue *

gtk/gtkcssfiltervalue.c

@@ -307,55 +307,56 @@ gtk_css_value_filter_free (GtkCssValue *value)
 
 /* returns TRUE if dest == src */
 static gboolean
-gtk_css_filter_compute (GtkCssFilter     *dest,
-                        GtkCssFilter     *src,
-                        guint             property_id,
-                        GtkStyleProvider *provider,
-                        GtkCssStyle      *style,
-                        GtkCssStyle      *parent_style)
+gtk_css_filter_compute (GtkCssFilter      *dest,
+                        GtkCssFilter      *src,
+                        guint              property_id,
+                        GtkStyleProvider  *provider,
+                        GtkCssStyle       *style,
+                        GtkCssStyle       *parent_style,
+                        GtkCssVariableSet *variables)
 {
   dest->type = src->type;
 
   switch (src->type)
     {
     case GTK_CSS_FILTER_BRIGHTNESS:
-      dest->brightness.value = _gtk_css_value_compute (src->brightness.value, property_id, provider, style, parent_style);
+      dest->brightness.value = _gtk_css_value_compute (src->brightness.value, property_id, provider, style, parent_style, variables);
       return dest->brightness.value == src->brightness.value;
 
     case GTK_CSS_FILTER_CONTRAST:
-      dest->contrast.value = _gtk_css_value_compute (src->contrast.value, property_id, provider, style, parent_style);
+      dest->contrast.value = _gtk_css_value_compute (src->contrast.value, property_id, provider, style, parent_style, variables);
       return dest->contrast.value == src->contrast.value;
 
     case GTK_CSS_FILTER_GRAYSCALE:
-      dest->grayscale.value = _gtk_css_value_compute (src->grayscale.value, property_id, provider, style, parent_style);
+      dest->grayscale.value = _gtk_css_value_compute (src->grayscale.value, property_id, provider, style, parent_style, variables);
       return dest->grayscale.value == src->grayscale.value;
 
     case GTK_CSS_FILTER_HUE_ROTATE:
-      dest->hue_rotate.value = _gtk_css_value_compute (src->hue_rotate.value, property_id, provider, style, parent_style);
+      dest->hue_rotate.value = _gtk_css_value_compute (src->hue_rotate.value, property_id, provider, style, parent_style, variables);
       return dest->hue_rotate.value == src->hue_rotate.value;
 
     case GTK_CSS_FILTER_INVERT:
-      dest->invert.value = _gtk_css_value_compute (src->invert.value, property_id, provider, style, parent_style);
+      dest->invert.value = _gtk_css_value_compute (src->invert.value, property_id, provider, style, parent_style, variables);
       return dest->invert.value == src->invert.value;
 
     case GTK_CSS_FILTER_OPACITY:
-      dest->opacity.value = _gtk_css_value_compute (src->opacity.value, property_id, provider, style, parent_style);
+      dest->opacity.value = _gtk_css_value_compute (src->opacity.value, property_id, provider, style, parent_style, variables);
       return dest->opacity.value == src->opacity.value;
 
     case GTK_CSS_FILTER_SATURATE:
-      dest->saturate.value = _gtk_css_value_compute (src->saturate.value, property_id, provider, style, parent_style);
+      dest->saturate.value = _gtk_css_value_compute (src->saturate.value, property_id, provider, style, parent_style, variables);
       return dest->saturate.value == src->saturate.value;
 
     case GTK_CSS_FILTER_SEPIA:
-      dest->sepia.value = _gtk_css_value_compute (src->sepia.value, property_id, provider, style, parent_style);
+      dest->sepia.value = _gtk_css_value_compute (src->sepia.value, property_id, provider, style, parent_style, variables);
       return dest->sepia.value == src->sepia.value;
 
     case GTK_CSS_FILTER_BLUR:
-      dest->blur.value = _gtk_css_value_compute (src->blur.value, property_id, provider, style, parent_style);
+      dest->blur.value = _gtk_css_value_compute (src->blur.value, property_id, provider, style, parent_style, variables);
       return dest->blur.value == src->blur.value;
 
     case GTK_CSS_FILTER_DROP_SHADOW:
-      dest->drop_shadow.value = _gtk_css_value_compute (src->drop_shadow.value, property_id, provider, style, parent_style);
+      dest->drop_shadow.value = _gtk_css_value_compute (src->drop_shadow.value, property_id, provider, style, parent_style, variables);
       return dest->drop_shadow.value == src->drop_shadow.value;
 
     case GTK_CSS_FILTER_NONE:
@@ -366,11 +367,12 @@ gtk_css_filter_compute (GtkCssFilter     *dest,
 }
 
 static GtkCssValue *
-gtk_css_value_filter_compute (GtkCssValue      *value,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_value_filter_compute (GtkCssValue       *value,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   GtkCssValue *result;
   gboolean changes;
@@ -390,7 +392,8 @@ gtk_css_value_filter_compute (GtkCssValue      *value,
                                           property_id,
                                           provider,
                                           style,
-                                          parent_style);
+                                          parent_style,
+                                          variables);
     }
 
   if (!changes)
@@ -723,7 +726,7 @@ static const GtkCssValueClass GTK_CSS_VALUE_FILTER = {
   gtk_css_value_filter_print
 };
 
-static GtkCssValue filter_none_singleton = { &GTK_CSS_VALUE_FILTER, 1, TRUE, 0, {  { GTK_CSS_FILTER_NONE } } };
+static GtkCssValue filter_none_singleton = { &GTK_CSS_VALUE_FILTER, 1, TRUE, FALSE, 0, {  { GTK_CSS_FILTER_NONE } } };
 
 static GtkCssValue *
 gtk_css_filter_value_alloc (guint n_filters)

gtk/gtkcssfontfeaturesvalue.c

@@ -53,11 +53,12 @@ gtk_css_value_font_features_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_font_features_compute (GtkCssValue      *specified,
-                                     guint             property_id,
-                                     GtkStyleProvider *provider,
-                                     GtkCssStyle      *style,
-                                     GtkCssStyle      *parent_style)
+gtk_css_value_font_features_compute (GtkCssValue       *specified,
+                                     guint              property_id,
+                                     GtkStyleProvider  *provider,
+                                     GtkCssStyle       *style,
+                                     GtkCssStyle       *parent_style,
+                                     GtkCssVariableSet *variables)
 {
   return _gtk_css_value_ref (specified);
 }

gtk/gtkcssfontvariationsvalue.c

@@ -52,11 +52,12 @@ gtk_css_value_font_variations_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_font_variations_compute (GtkCssValue      *specified,
-                                       guint             property_id,
-                                       GtkStyleProvider *provider,
-                                       GtkCssStyle      *style,
-                                       GtkCssStyle      *parent_style)
+gtk_css_value_font_variations_compute (GtkCssValue       *specified,
+                                       guint              property_id,
+                                       GtkStyleProvider  *provider,
+                                       GtkCssStyle       *style,
+                                       GtkCssStyle       *parent_style,
+                                       GtkCssVariableSet *variables)
 {
   return _gtk_css_value_ref (specified);
 }

gtk/gtkcssimage.c

@@ -65,11 +65,12 @@ gtk_css_image_real_get_aspect_ratio (GtkCssImage *image)
 }
 
 static GtkCssImage *
-gtk_css_image_real_compute (GtkCssImage      *image,
-                            guint             property_id,
-                            GtkStyleProvider *provider,
-                            GtkCssStyle      *style,
-                            GtkCssStyle      *parent_style)
+gtk_css_image_real_compute (GtkCssImage       *image,
+                            guint              property_id,
+                            GtkStyleProvider  *provider,
+                            GtkCssStyle       *style,
+                            GtkCssStyle       *parent_style,
+                            GtkCssVariableSet *variables)
 {
   return g_object_ref (image);
 }
@@ -173,11 +174,12 @@ _gtk_css_image_get_aspect_ratio (GtkCssImage *image)
 }
 
 GtkCssImage *
-_gtk_css_image_compute (GtkCssImage      *image,
-                        guint             property_id,
-                        GtkStyleProvider *provider,
-                        GtkCssStyle      *style,
-                        GtkCssStyle      *parent_style)
+_gtk_css_image_compute (GtkCssImage       *image,
+                        guint              property_id,
+                        GtkStyleProvider  *provider,
+                        GtkCssStyle       *style,
+                        GtkCssStyle       *parent_style,
+                        GtkCssVariableSet *variables)
 {
   GtkCssImageClass *klass;
 
@@ -187,7 +189,7 @@ _gtk_css_image_compute (GtkCssImage      *image,
 
   klass = GTK_CSS_IMAGE_GET_CLASS (image);
 
-  return klass->compute (image, property_id, provider, style, parent_style);
+  return klass->compute (image, property_id, provider, style, parent_style, variables);
 }
 
 GtkCssImage *

gtk/gtkcssimageconic.c

@@ -313,11 +313,12 @@ gtk_css_image_conic_print (GtkCssImage *image,
 }
 
 static GtkCssImage *
-gtk_css_image_conic_compute (GtkCssImage      *image,
-                             guint             property_id,
-                             GtkStyleProvider *provider,
-                             GtkCssStyle      *style,
-                             GtkCssStyle      *parent_style)
+gtk_css_image_conic_compute (GtkCssImage       *image,
+                             guint              property_id,
+                             GtkStyleProvider  *provider,
+                             GtkCssStyle       *style,
+                             GtkCssStyle       *parent_style,
+                             GtkCssVariableSet *variables)
 {
   GtkCssImageConic *self = GTK_CSS_IMAGE_CONIC (image);
   GtkCssImageConic *copy;
@@ -325,8 +326,8 @@ gtk_css_image_conic_compute (GtkCssImage      *image,
 
   copy = g_object_new (GTK_TYPE_CSS_IMAGE_CONIC, NULL);
 
-  copy->center = _gtk_css_value_compute (self->center, property_id, provider, style, parent_style);
-  copy->rotation = _gtk_css_value_compute (self->rotation, property_id, provider, style, parent_style);
+  copy->center = _gtk_css_value_compute (self->center, property_id, provider, style, parent_style, variables);
+  copy->rotation = _gtk_css_value_compute (self->rotation, property_id, provider, style, parent_style, variables);
 
   copy->n_stops = self->n_stops;
   copy->color_stops = g_malloc (sizeof (GtkCssImageConicColorStop) * copy->n_stops);
@@ -335,11 +336,11 @@ gtk_css_image_conic_compute (GtkCssImage      *image,
       const GtkCssImageConicColorStop *stop = &self->color_stops[i];
       GtkCssImageConicColorStop *scopy = &copy->color_stops[i];
 
-      scopy->color = _gtk_css_value_compute (stop->color, property_id, provider, style, parent_style);
+      scopy->color = _gtk_css_value_compute (stop->color, property_id, provider, style, parent_style, variables);
 
       if (stop->offset)
         {
-          scopy->offset = _gtk_css_value_compute (stop->offset, property_id, provider, style, parent_style);
+          scopy->offset = _gtk_css_value_compute (stop->offset, property_id, provider, style, parent_style, variables);
         }
       else
         {

gtk/gtkcssimagecrossfade.c

@@ -399,11 +399,12 @@ gtk_css_image_cross_fade_print (GtkCssImage *image,
 }
 
 static GtkCssImage *
-gtk_css_image_cross_fade_compute (GtkCssImage      *image,
-                                  guint             property_id,
-                                  GtkStyleProvider *provider,
-                                  GtkCssStyle      *style,
-                                  GtkCssStyle      *parent_style)
+gtk_css_image_cross_fade_compute (GtkCssImage       *image,
+                                  guint              property_id,
+                                  GtkStyleProvider  *provider,
+                                  GtkCssStyle       *style,
+                                  GtkCssStyle       *parent_style,
+                                  GtkCssVariableSet *variables)
 {
   GtkCssImageCrossFade *self = GTK_CSS_IMAGE_CROSS_FADE (image);
   GtkCssImageCrossFade *result;
@@ -418,7 +419,7 @@ gtk_css_image_cross_fade_compute (GtkCssImage      *image,
       gtk_css_image_cross_fade_add (result,
                                     entry->has_progress,
                                     entry->progress,
-                                    _gtk_css_image_compute (entry->image, property_id, provider, style, parent_style));
+                                    _gtk_css_image_compute (entry->image, property_id, provider, style, parent_style, variables));
     }
 
   return GTK_CSS_IMAGE (result);

gtk/gtkcssimagefallback.c

@@ -133,11 +133,12 @@ gtk_css_image_fallback_dispose (GObject *object)
 
 
 static GtkCssImage *
-gtk_css_image_fallback_compute (GtkCssImage      *image,
-                                guint             property_id,
-                                GtkStyleProvider *provider,
-                                GtkCssStyle      *style,
-                                GtkCssStyle      *parent_style)
+gtk_css_image_fallback_compute (GtkCssImage       *image,
+                                guint              property_id,
+                                GtkStyleProvider  *provider,
+                                GtkCssStyle       *style,
+                                GtkCssStyle       *parent_style,
+                                GtkCssVariableSet *variables)
 {
   GtkCssImageFallback *fallback = GTK_CSS_IMAGE_FALLBACK (image);
   GtkCssImageFallback *copy;
@@ -152,7 +153,8 @@ gtk_css_image_fallback_compute (GtkCssImage      *image,
                                                  property_id,
                                                  provider,
                                                  style,
-                                                 parent_style);
+                                                 parent_style,
+                                                 variables);
 
       /* image($color) that didn't change */
       if (computed_color && !fallback->images &&
@@ -168,7 +170,8 @@ gtk_css_image_fallback_compute (GtkCssImage      *image,
                                                     property_id,
                                                     provider,
                                                     style,
-                                                    parent_style);
+                                                    parent_style,
+                                                    variables);
 
           if (gtk_css_image_is_invalid (copy->images[i]))
             continue;

gtk/gtkcssimageicontheme.c

@@ -138,11 +138,12 @@ gtk_css_image_icon_theme_print (GtkCssImage *image,
 }
 
 static GtkCssImage *
-gtk_css_image_icon_theme_compute (GtkCssImage      *image,
-                                  guint             property_id,
-                                  GtkStyleProvider *provider,
-                                  GtkCssStyle      *style,
-                                  GtkCssStyle      *parent_style)
+gtk_css_image_icon_theme_compute (GtkCssImage       *image,
+                                  guint              property_id,
+                                  GtkStyleProvider  *provider,
+                                  GtkCssStyle       *style,
+                                  GtkCssStyle       *parent_style,
+                                  GtkCssVariableSet *variables)
 {
   GtkCssImageIconTheme *icon_theme = GTK_CSS_IMAGE_ICON_THEME (image);
   GtkCssImageIconTheme *copy;

gtk/gtkcssimagelinear.c

@@ -488,11 +488,12 @@ gtk_css_image_linear_print (GtkCssImage *image,
 }
 
 static GtkCssImage *
-gtk_css_image_linear_compute (GtkCssImage      *image,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_image_linear_compute (GtkCssImage       *image,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   GtkCssImageLinear *linear = GTK_CSS_IMAGE_LINEAR (image);
   GtkCssImageLinear *copy;
@@ -503,7 +504,7 @@ gtk_css_image_linear_compute (GtkCssImage      *image,
   copy->side = linear->side;
 
   if (linear->angle)
-    copy->angle = _gtk_css_value_compute (linear->angle, property_id, provider, style, parent_style);
+    copy->angle = _gtk_css_value_compute (linear->angle, property_id, provider, style, parent_style, variables);
 
   copy->n_stops = linear->n_stops;
   copy->color_stops = g_malloc (sizeof (GtkCssImageLinearColorStop) * copy->n_stops);
@@ -512,11 +513,11 @@ gtk_css_image_linear_compute (GtkCssImage      *image,
       const GtkCssImageLinearColorStop *stop = &linear->color_stops[i];
       GtkCssImageLinearColorStop *scopy = &copy->color_stops[i];
 
-      scopy->color = _gtk_css_value_compute (stop->color, property_id, provider, style, parent_style);
+      scopy->color = _gtk_css_value_compute (stop->color, property_id, provider, style, parent_style, variables);
 
       if (stop->offset)
         {
-          scopy->offset = _gtk_css_value_compute (stop->offset, property_id, provider, style, parent_style);
+          scopy->offset = _gtk_css_value_compute (stop->offset, property_id, provider, style, parent_style, variables);
         }
       else
         {

gtk/gtkcssimagepaintable.c

@@ -96,11 +96,12 @@ gtk_css_image_paintable_get_static_image (GtkCssImage *image)
 }
 
 static GtkCssImage *
-gtk_css_image_paintable_compute (GtkCssImage      *image,
-                                 guint             property_id,
-                                 GtkStyleProvider *provider,
-                                 GtkCssStyle      *style,
-                                 GtkCssStyle      *parent_style)
+gtk_css_image_paintable_compute (GtkCssImage       *image,
+                                 guint              property_id,
+                                 GtkStyleProvider  *provider,
+                                 GtkCssStyle       *style,
+                                 GtkCssStyle       *parent_style,
+                                 GtkCssVariableSet *variables)
 {
   return gtk_css_image_paintable_get_static_image (image);
 }

gtk/gtkcssimageprivate.h

@@ -26,6 +26,7 @@
 #include "gtk/css/gtkcsstokenizerprivate.h"
 #include "gtk/css/gtkcssparserprivate.h"
 #include "gtk/gtkcsstypesprivate.h"
+#include "gtk/gtkcssvariablesetprivate.h"
 #include "gtk/gtksnapshot.h"
 #include "gtk/gtkstyleprovider.h"
 
@@ -62,7 +63,8 @@ struct _GtkCssImageClass
                                                     guint                       property_id,
                                                     GtkStyleProvider           *provider,
                                                     GtkCssStyle                *style,
-                                                    GtkCssStyle                *parent_style);
+                                                    GtkCssStyle                *parent_style,
+                                                    GtkCssVariableSet          *variables);
   /* compare two images for equality */
   gboolean     (* equal)                           (GtkCssImage                *image1,
                                                     GtkCssImage                *image2);
@@ -106,7 +108,8 @@ GtkCssImage *  _gtk_css_image_compute              (GtkCssImage                *
                                                     guint                       property_id,
                                                     GtkStyleProvider           *provider,
                                                     GtkCssStyle                *style,
-                                                    GtkCssStyle                *parent_style);
+                                                    GtkCssStyle                *parent_style,
+                                                    GtkCssVariableSet          *variables);
 gboolean       _gtk_css_image_equal                (GtkCssImage                *image1,
                                                     GtkCssImage                *image2) G_GNUC_PURE;
 GtkCssImage *  _gtk_css_image_transition           (GtkCssImage                *start,

gtk/gtkcssimageradial.c

@@ -489,11 +489,12 @@ gtk_css_image_radial_print (GtkCssImage *image,
 }
 
 static GtkCssImage *
-gtk_css_image_radial_compute (GtkCssImage      *image,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_image_radial_compute (GtkCssImage       *image,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   GtkCssImageRadial *radial = GTK_CSS_IMAGE_RADIAL (image);
   GtkCssImageRadial *copy;
@@ -504,13 +505,13 @@ gtk_css_image_radial_compute (GtkCssImage      *image,
   copy->circle = radial->circle;
   copy->size = radial->size;
 
-  copy->position = _gtk_css_value_compute (radial->position, property_id, provider, style, parent_style);
+  copy->position = _gtk_css_value_compute (radial->position, property_id, provider, style, parent_style, variables);
 
   if (radial->sizes[0])
-    copy->sizes[0] = _gtk_css_value_compute (radial->sizes[0], property_id, provider, style, parent_style);
+    copy->sizes[0] = _gtk_css_value_compute (radial->sizes[0], property_id, provider, style, parent_style, variables);
 
   if (radial->sizes[1])
-    copy->sizes[1] = _gtk_css_value_compute (radial->sizes[1], property_id, provider, style, parent_style);
+    copy->sizes[1] = _gtk_css_value_compute (radial->sizes[1], property_id, provider, style, parent_style, variables);
 
   copy->n_stops = radial->n_stops;
   copy->color_stops = g_malloc (sizeof (GtkCssImageRadialColorStop) * copy->n_stops);
@@ -519,11 +520,11 @@ gtk_css_image_radial_compute (GtkCssImage      *image,
       const GtkCssImageRadialColorStop *stop = &radial->color_stops[i];
       GtkCssImageRadialColorStop *scopy = &copy->color_stops[i];
 
-      scopy->color = _gtk_css_value_compute (stop->color, property_id, provider, style, parent_style);
+      scopy->color = _gtk_css_value_compute (stop->color, property_id, provider, style, parent_style, variables);
 
       if (stop->offset)
         {
-          scopy->offset = _gtk_css_value_compute (stop->offset, property_id, provider, style, parent_style);
+          scopy->offset = _gtk_css_value_compute (stop->offset, property_id, provider, style, parent_style, variables);
         }
       else
         {

gtk/gtkcssimagerecolor.c

@@ -201,11 +201,12 @@ gtk_css_image_recolor_snapshot (GtkCssImage *image,
 }
 
 static GtkCssImage *
-gtk_css_image_recolor_compute (GtkCssImage      *image,
-                               guint             property_id,
-                               GtkStyleProvider *provider,
-                               GtkCssStyle      *style,
-                               GtkCssStyle      *parent_style)
+gtk_css_image_recolor_compute (GtkCssImage       *image,
+                               guint              property_id,
+                               GtkStyleProvider  *provider,
+                               GtkCssStyle       *style,
+                               GtkCssStyle       *parent_style,
+                               GtkCssVariableSet *variables)
 {
   GtkCssImageRecolor *recolor = GTK_CSS_IMAGE_RECOLOR (image);
   GtkCssValue *palette;
@@ -216,7 +217,7 @@ gtk_css_image_recolor_compute (GtkCssImage      *image,
   scale = gtk_style_provider_get_scale (provider);
 
   if (recolor->palette)
-    palette = _gtk_css_value_compute (recolor->palette, property_id, provider, style, parent_style);
+    palette = _gtk_css_value_compute (recolor->palette, property_id, provider, style, parent_style, variables);
   else
     palette = _gtk_css_value_ref (style->core->icon_palette);
 

gtk/gtkcssimagescaled.c

@@ -97,11 +97,12 @@ gtk_css_image_scaled_dispose (GObject *object)
 
 
 static GtkCssImage *
-gtk_css_image_scaled_compute (GtkCssImage      *image,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_image_scaled_compute (GtkCssImage       *image,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   GtkCssImageScaled *scaled = GTK_CSS_IMAGE_SCALED (image);
   int scale;
@@ -137,7 +138,8 @@ gtk_css_image_scaled_compute (GtkCssImage      *image,
                                            property_id,
                                            provider,
                                            style,
-                                           parent_style);
+                                           parent_style,
+                                           variables);
   res->scales[0] = scaled->scales[best];
 
   return GTK_CSS_IMAGE (res);

gtk/gtkcssimageurl.c

@@ -112,11 +112,12 @@ gtk_css_image_url_snapshot (GtkCssImage *image,
 }
 
 static GtkCssImage *
-gtk_css_image_url_compute (GtkCssImage      *image,
-                           guint             property_id,
-                           GtkStyleProvider *provider,
-                           GtkCssStyle      *style,
-                           GtkCssStyle      *parent_style)
+gtk_css_image_url_compute (GtkCssImage       *image,
+                           guint              property_id,
+                           GtkStyleProvider  *provider,
+                           GtkCssStyle       *style,
+                           GtkCssStyle       *parent_style,
+                           GtkCssVariableSet *variables)
 {
   GtkCssImageUrl *url = GTK_CSS_IMAGE_URL (image);
   GtkCssImage *copy;

gtk/gtkcssimagevalue.c

@@ -34,11 +34,12 @@ gtk_css_value_image_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_image_compute (GtkCssValue      *value,
-                             guint             property_id,
-                             GtkStyleProvider *provider,
-                             GtkCssStyle      *style,
-                             GtkCssStyle      *parent_style)
+gtk_css_value_image_compute (GtkCssValue       *value,
+                             guint              property_id,
+                             GtkStyleProvider  *provider,
+                             GtkCssStyle       *style,
+                             GtkCssStyle       *parent_style,
+                             GtkCssVariableSet *variables)
 {
   GtkCssImage *image, *computed;
   
@@ -47,7 +48,7 @@ gtk_css_value_image_compute (GtkCssValue      *value,
   if (image == NULL)
     return _gtk_css_value_ref (value);
 
-  computed = _gtk_css_image_compute (image, property_id, provider, style, parent_style);
+  computed = _gtk_css_image_compute (image, property_id, provider, style, parent_style, variables);
 
   if (computed == image)
     {
@@ -136,7 +137,7 @@ static const GtkCssValueClass GTK_CSS_VALUE_IMAGE = {
 GtkCssValue *
 _gtk_css_image_value_new (GtkCssImage *image)
 {
-  static GtkCssValue image_none_singleton = { &GTK_CSS_VALUE_IMAGE, 1, TRUE, NULL };
+  static GtkCssValue image_none_singleton = { &GTK_CSS_VALUE_IMAGE, 1, TRUE, FALSE, NULL };
   GtkCssValue *value;
 
   if (image == NULL)

gtk/gtkcssinheritvalue.c

@@ -34,11 +34,12 @@ gtk_css_value_inherit_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_inherit_compute (GtkCssValue      *value,
-                               guint             property_id,
-                               GtkStyleProvider *provider,
-                               GtkCssStyle      *style,
-                               GtkCssStyle      *parent_style)
+gtk_css_value_inherit_compute (GtkCssValue       *value,
+                               guint              property_id,
+                               GtkStyleProvider  *provider,
+                               GtkCssStyle       *style,
+                               GtkCssStyle       *parent_style,
+                               GtkCssVariableSet *variables)
 {
   if (parent_style)
     {
@@ -50,7 +51,8 @@ gtk_css_value_inherit_compute (GtkCssValue      *value,
                                      property_id,
                                      provider,
                                      style,
-                                     parent_style);
+                                     parent_style,
+                                     variables);
     }
 }
 

gtk/gtkcssinitialvalue.c

@@ -38,11 +38,12 @@ gtk_css_value_initial_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_initial_compute (GtkCssValue      *value,
-                               guint             property_id,
-                               GtkStyleProvider *provider,
-                               GtkCssStyle      *style,
-                               GtkCssStyle      *parent_style)
+gtk_css_value_initial_compute (GtkCssValue       *value,
+                               guint              property_id,
+                               GtkStyleProvider  *provider,
+                               GtkCssStyle       *style,
+                               GtkCssStyle       *parent_style,
+                               GtkCssVariableSet *variables)
 {
   GtkSettings *settings;
 
@@ -75,7 +76,8 @@ gtk_css_value_initial_compute (GtkCssValue      *value,
                                  property_id,
                                  provider,
                                  style,
-                                 parent_style);
+                                 parent_style,
+                                 variables);
 }
 
 static gboolean
@@ -135,5 +137,6 @@ _gtk_css_initial_value_new_compute (guint             property_id,
                                         property_id,
                                         provider,
                                         style,
-                                        parent_style);
+                                        parent_style,
+                                        NULL);
 }

gtk/gtkcsskeyframes.c

@@ -21,6 +21,8 @@
 
 #include "gtkcssstyleprivate.h"
 #include "gtkcssarrayvalueprivate.h"
+#include "gtkcsscustompropertypoolprivate.h"
+#include "gtkcssreferencevalueprivate.h"
 #include "gtkcssshorthandpropertyprivate.h"
 #include "gtkcssstylepropertyprivate.h"
 #include "gtkstylepropertyprivate.h"
@@ -31,12 +33,15 @@
 #include <string.h>
 
 struct _GtkCssKeyframes {
-  int ref_count;                /* ref count */
-  int n_keyframes;              /* number of keyframes (at least 2 for 0% and 100% */
-  double *keyframe_progress;    /* ordered array of n_keyframes of [0..1] */
-  int n_properties;             /* number of properties used by keyframes */
-  guint *property_ids;          /* ordered array of n_properties property ids */
-  GtkCssValue **values;         /* 2D array: n_keyframes * n_properties of (value or NULL) for all the keyframes */
+  int ref_count;                 /* ref count */
+  int n_keyframes;               /* number of keyframes (at least 2 for 0% and 100% */
+  double *keyframe_progress;     /* ordered array of n_keyframes of [0..1] */
+  int n_properties;              /* number of properties used by keyframes */
+  guint *property_ids;           /* ordered array of n_properties property ids */
+  GtkCssValue **values;          /* 2D array: n_keyframes * n_properties of (value or NULL) for all the keyframes */
+  GtkCssVariableSet **variables; /* array of variable sets for each keyframe */
+  int *variable_ids;             /* ordered array of variable ids */
+  int n_variables;               /* number of variable used by keyframes */
 };
 
 #define KEYFRAMES_VALUE(keyframes, k, p) ((keyframes)->values[(k) * (keyframes)->n_properties + (p)])
@@ -72,8 +77,13 @@ _gtk_css_keyframes_unref (GtkCssKeyframes *keyframes)
           _gtk_css_value_unref (KEYFRAMES_VALUE (keyframes, k, p));
           KEYFRAMES_VALUE (keyframes, k, p) = NULL;
         }
+
+      if (keyframes->variables && keyframes->variables[k])
+        gtk_css_variable_set_unref (keyframes->variables[k]);
     }
   g_free (keyframes->values);
+  g_free (keyframes->variables);
+  g_free (keyframes->variable_ids);
 
   g_free (keyframes);
 }
@@ -120,6 +130,9 @@ gtk_css_keyframes_add_keyframe (GtkCssKeyframes *keyframes,
       memset (&KEYFRAMES_VALUE (keyframes, k, 0), 0, size);
     }
 
+  if (keyframes->variables)
+    keyframes->variables = g_realloc (keyframes->variables, sizeof (GtkCssVariableSet *) * keyframes->n_keyframes);
+
   return k;
 }
 
@@ -173,6 +186,26 @@ gtk_css_keyframes_lookup_property (GtkCssKeyframes *keyframes,
   return p;
 }
 
+static void
+gtk_css_keyframes_register_variable (GtkCssKeyframes *keyframes,
+                                     int              variable_id)
+{
+  guint p;
+
+  for (p = 0; p < keyframes->n_variables; p++)
+    {
+      if (keyframes->variable_ids[p] == variable_id)
+        return;
+      else if (keyframes->variable_ids[p] > variable_id)
+        break;
+    }
+
+  keyframes->n_variables++;
+  keyframes->variable_ids = g_realloc (keyframes->variable_ids, sizeof (int) * keyframes->n_variables);
+  memmove (keyframes->variable_ids + p + 1, keyframes->variable_ids + p, sizeof (int) * (keyframes->n_variables - p - 1));
+  keyframes->variable_ids[p] = variable_id;
+}
+
 static GtkCssKeyframes *
 gtk_css_keyframes_alloc (void)
 {
@@ -235,6 +268,47 @@ gtk_css_keyframes_parse_declaration (GtkCssKeyframes *keyframes,
       return FALSE;
     }
 
+  /* This is a custom property */
+  if (name[0] == '-' && name[1] == '-')
+    {
+      GtkCssVariableValue *var_value;
+      GtkCssCustomPropertyPool *pool;
+      int id;
+
+      if (!gtk_css_parser_try_token (parser, GTK_CSS_TOKEN_COLON))
+        {
+          gtk_css_parser_error_syntax (parser, "Expected a ':'");
+          g_free (name);
+          return FALSE;
+        }
+
+      var_value = gtk_css_parser_parse_value_into_token_stream (parser);
+      if (var_value == NULL)
+        {
+          g_free (name);
+          return FALSE;
+        }
+
+      if (!keyframes->variables)
+        keyframes->variables = g_new0 (GtkCssVariableSet *, keyframes->n_keyframes);
+
+      if (!keyframes->variables[k])
+        keyframes->variables[k] = gtk_css_variable_set_new ();
+
+      pool = gtk_css_custom_property_pool_get ();
+      id = gtk_css_custom_property_pool_add (pool, name);
+      gtk_css_keyframes_register_variable (keyframes, id);
+
+      gtk_css_variable_value_taint (var_value);
+
+      gtk_css_variable_set_add (keyframes->variables[k], id, var_value);
+
+      gtk_css_custom_property_pool_unref (pool, id);
+
+      g_free (name);
+      return TRUE;
+    }
+
   property = _gtk_style_property_lookup (name);
   if (property == NULL)
     {
@@ -251,9 +325,53 @@ gtk_css_keyframes_parse_declaration (GtkCssKeyframes *keyframes,
       return FALSE;
     }
 
-  value = _gtk_style_property_parse_value (property, parser);
-  if (value == NULL)
-    return FALSE;
+  if (gtk_css_parser_has_references (parser))
+    {
+      GtkCssVariableValue *var_value;
+
+      var_value = gtk_css_parser_parse_value_into_token_stream (parser);
+      if (var_value == NULL)
+        return FALSE;
+
+      if (GTK_IS_CSS_SHORTHAND_PROPERTY (property))
+        {
+          GtkCssShorthandProperty *shorthand = GTK_CSS_SHORTHAND_PROPERTY (property);
+          guint i, n;
+          GtkCssValue **values;
+
+          n = _gtk_css_shorthand_property_get_n_subproperties (shorthand);
+
+          values = g_new (GtkCssValue *, n);
+
+          for (i = 0; i < n; i++)
+            {
+              GtkCssValue *child =
+                _gtk_css_reference_value_new (property,
+                                              var_value,
+                                              gtk_css_parser_get_file (parser));
+              _gtk_css_reference_value_set_subproperty (child, i);
+
+              values[i] = _gtk_css_array_value_get_nth (child, i);
+            }
+
+          value = _gtk_css_array_value_new_from_array (values, n);
+          g_free (values);
+        }
+      else
+        {
+          value = _gtk_css_reference_value_new (property,
+                                                var_value,
+                                                gtk_css_parser_get_file (parser));
+        }
+
+      gtk_css_variable_value_unref (var_value);
+    }
+  else
+    {
+      value = _gtk_style_property_parse_value (property, parser);
+      if (value == NULL)
+        return FALSE;
+    }
 
   if (!gtk_css_parser_has_token (parser, GTK_CSS_TOKEN_EOF))
     {
@@ -314,6 +432,9 @@ gtk_css_keyframes_parse_block (GtkCssKeyframes *keyframes,
       gtk_css_parser_end_block (parser);
     }
 
+  if (keyframes->variables && keyframes->variables[k])
+    gtk_css_variable_set_resolve_cycles (keyframes->variables[k]);
+
   gtk_css_parser_end_block (parser);
 
   return TRUE;
@@ -378,12 +499,27 @@ compare_property_by_name (gconstpointer a,
                     _gtk_css_style_property_lookup_by_id (keyframes->property_ids[*(const guint *) b]))));
 }
 
+static int
+compare_custom_property_ids (gconstpointer a, gconstpointer b, gpointer user_data)
+{
+  GtkCssCustomPropertyPool *pool = user_data;
+  int id1 = GPOINTER_TO_INT (*((const int *) a));
+  int id2 = GPOINTER_TO_INT (*((const int *) b));
+  const char *name1, *name2;
+
+  name1 = gtk_css_custom_property_pool_get_name (pool, id1);
+  name2 = gtk_css_custom_property_pool_get_name (pool, id2);
+
+  return strcmp (name1, name2);
+}
+
 void
 _gtk_css_keyframes_print (GtkCssKeyframes *keyframes,
                           GString         *string)
 {
+  GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
   guint k, p;
-  guint *sorted;
+  guint *sorted, *sorted_variable_ids = NULL;
 
   g_return_if_fail (keyframes != NULL);
   g_return_if_fail (string != NULL);
@@ -393,6 +529,18 @@ _gtk_css_keyframes_print (GtkCssKeyframes *keyframes,
     sorted[p] = p;
   g_qsort_with_data (sorted, keyframes->n_properties, sizeof (guint), compare_property_by_name, keyframes);
 
+  if (keyframes->variable_ids)
+    {
+      sorted_variable_ids = g_memdup2 (keyframes->variable_ids,
+                                       sizeof (int) * keyframes->n_variables);
+
+      g_qsort_with_data (sorted_variable_ids,
+                         keyframes->n_variables,
+                         sizeof (int),
+                         compare_custom_property_ids,
+                         pool);
+    }
+
   for (k = 0; k < keyframes->n_keyframes; k++)
     {
       /* useful for 0% and 100% which might be empty */
@@ -422,11 +570,43 @@ _gtk_css_keyframes_print (GtkCssKeyframes *keyframes,
           g_string_append (string, ";\n");
         }
 
+      if (keyframes->variables && keyframes->variables[k])
+        {
+          for (p = 0; p < keyframes->n_variables; p++)
+            {
+              int variable_id = sorted_variable_ids[p];
+              GtkCssVariableValue *value =
+                gtk_css_variable_set_lookup (keyframes->variables[k], variable_id, NULL);
+              const char *name;
+
+              if (value == NULL)
+                continue;
+
+              if (!opened)
+                {
+                  if (keyframes->keyframe_progress[k] == 0.0)
+                    g_string_append (string, "  from {\n");
+                  else if (keyframes->keyframe_progress[k] == 1.0)
+                    g_string_append (string, "  to {\n");
+                  else
+                    g_string_append_printf (string, "  %g%% {\n", keyframes->keyframe_progress[k] * 100);
+                  opened = TRUE;
+                }
+
+              name = gtk_css_custom_property_pool_get_name (pool, variable_id);
+
+              g_string_append_printf (string, "    %s: ", name);
+              gtk_css_variable_value_print (value, string);
+              g_string_append (string, ";\n");
+            }
+        }
+
       if (opened)
         g_string_append (string, "  }\n");
     }
 
   g_free (sorted);
+  g_free (sorted_variable_ids);
 }
 
 GtkCssKeyframes *
@@ -461,10 +641,27 @@ _gtk_css_keyframes_compute (GtkCssKeyframes  *keyframes,
                                                                       resolved->property_ids[p],
                                                                       provider,
                                                                       style,
-                                                                      parent_style);
+                                                                      parent_style,
+                                                                      keyframes->variables ? keyframes->variables[k] : NULL);
         }
     }
 
+  if (keyframes->variables)
+    {
+      resolved->variables = g_new0 (GtkCssVariableSet *, resolved->n_keyframes);
+
+      for (k = 0; k < resolved->n_keyframes; k++)
+        {
+          if (keyframes->variables[k])
+            resolved->variables[k] = gtk_css_variable_set_ref (keyframes->variables[k]);
+        }
+    }
+  else
+    resolved->variables = NULL;
+
+  resolved->variable_ids = g_memdup2 (keyframes->variable_ids, keyframes->n_variables * sizeof (int));
+  resolved->n_variables = keyframes->n_variables;
+
   return resolved;
 }
 
@@ -540,3 +737,83 @@ _gtk_css_keyframes_get_value (GtkCssKeyframes *keyframes,
   return result;
 }
 
+guint
+_gtk_css_keyframes_get_n_variables (GtkCssKeyframes *keyframes)
+{
+  g_return_val_if_fail (keyframes != NULL, 0);
+
+  return keyframes->n_variables;
+}
+
+int
+_gtk_css_keyframes_get_variable_id (GtkCssKeyframes *keyframes,
+                                    guint            id)
+{
+  g_return_val_if_fail (keyframes != NULL, 0);
+  g_return_val_if_fail (id < keyframes->n_variables, 0);
+
+  return keyframes->variable_ids[id];
+}
+
+GtkCssVariableValue *
+_gtk_css_keyframes_get_variable (GtkCssKeyframes     *keyframes,
+                                 guint                id,
+                                 double               progress,
+                                 GtkCssVariableValue *default_value)
+{
+  GtkCssVariableValue *start_value, *end_value, *result;
+  double start_progress, end_progress;
+  int variable_id;
+  guint k;
+
+  g_return_val_if_fail (keyframes != NULL, 0);
+  g_return_val_if_fail (id < keyframes->n_variables, 0);
+
+  start_value = default_value;
+  start_progress = 0.0;
+  end_value = default_value;
+  end_progress = 1.0;
+
+  variable_id = keyframes->variable_ids[id];
+
+  for (k = 0; k < keyframes->n_keyframes; k++)
+    {
+      GtkCssVariableValue *value;
+
+      if (keyframes->variables[k] == NULL)
+        continue;
+
+      value = gtk_css_variable_set_lookup (keyframes->variables[k], variable_id, NULL);
+
+      if (value == NULL)
+        continue;
+
+      if (keyframes->keyframe_progress[k] == progress)
+        {
+          return gtk_css_variable_value_ref (value);
+        }
+      else if (keyframes->keyframe_progress[k] < progress)
+        {
+          start_value = value;
+          start_progress = keyframes->keyframe_progress[k];
+        }
+      else
+        {
+          end_value = value;
+          end_progress = keyframes->keyframe_progress[k];
+          break;
+        }
+    }
+
+  progress = (progress - start_progress) / (end_progress - start_progress);
+
+  result = gtk_css_variable_value_transition (start_value,
+                                              end_value,
+                                              progress);
+
+  /* XXX: Dear spec, what's the correct thing to do here? */
+  if (result == NULL)
+    return start_value ? gtk_css_variable_value_ref (start_value) : NULL;
+
+  return result;
+}

gtk/gtkcsskeyframesprivate.h

@@ -50,5 +50,13 @@ GtkCssValue *       _gtk_css_keyframes_get_value              (GtkCssKeyframes
                                                                double                  progress,
                                                                GtkCssValue            *default_value);
 
+guint               _gtk_css_keyframes_get_n_variables        (GtkCssKeyframes        *keyframes);
+int                 _gtk_css_keyframes_get_variable_id        (GtkCssKeyframes        *keyframes,
+                                                               guint                   id);
+GtkCssVariableValue *_gtk_css_keyframes_get_variable          (GtkCssKeyframes        *keyframes,
+                                                               guint                   id,
+                                                               double                  progress,
+                                                               GtkCssVariableValue    *default_value);
+
 G_END_DECLS
 

gtk/gtkcsslineheightvalue.c

@@ -39,15 +39,16 @@ gtk_css_value_line_height_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_line_height_compute (GtkCssValue      *value,
-                                   guint             property_id,
-                                   GtkStyleProvider *provider,
-                                   GtkCssStyle      *style,
-                                   GtkCssStyle      *parent_style)
+gtk_css_value_line_height_compute (GtkCssValue       *value,
+                                   guint              property_id,
+                                   GtkStyleProvider  *provider,
+                                   GtkCssStyle       *style,
+                                   GtkCssStyle       *parent_style,
+                                   GtkCssVariableSet *variables)
 {
   GtkCssValue *height;
 
-  height = _gtk_css_value_compute (value->height, property_id, provider, style, parent_style);
+  height = _gtk_css_value_compute (value->height, property_id, provider, style, parent_style, variables);
 
   if (gtk_css_number_value_get_dimension (height) == GTK_CSS_DIMENSION_PERCENTAGE)
     {

gtk/gtkcsslookup.c

@@ -19,6 +19,7 @@
 
 #include "gtkcsslookupprivate.h"
 
+#include "gtkcsscustompropertypoolprivate.h"
 #include "gtkcssstylepropertyprivate.h"
 #include "gtkcsstypesprivate.h"
 #include "gtkprivatetypebuiltins.h"
@@ -36,6 +37,9 @@ void
 _gtk_css_lookup_destroy (GtkCssLookup *lookup)
 {
   _gtk_bitmask_free (lookup->set_values);
+
+  if (lookup->custom_values)
+    g_hash_table_unref (lookup->custom_values);
 }
 
 gboolean
@@ -74,3 +78,17 @@ _gtk_css_lookup_set (GtkCssLookup  *lookup,
   lookup->values[id].section = section;
   lookup->set_values = _gtk_bitmask_set (lookup->set_values, id, TRUE);
 }
+
+void
+_gtk_css_lookup_set_custom (GtkCssLookup        *lookup,
+                            int                  id,
+                            GtkCssVariableValue *value)
+{
+  gtk_internal_return_if_fail (lookup != NULL);
+
+  if (!lookup->custom_values)
+    lookup->custom_values = g_hash_table_new (g_direct_hash, g_direct_equal);
+
+  if (!g_hash_table_contains (lookup->custom_values, GINT_TO_POINTER (id)))
+    g_hash_table_replace (lookup->custom_values, GINT_TO_POINTER (id), value);
+}

gtk/gtkcsslookupprivate.h

@@ -23,6 +23,8 @@
 #include "gtk/gtkcssstaticstyleprivate.h"
 
 #include "gtk/css/gtkcsssection.h"
+#include "gtk/css/gtkcsstokenizerprivate.h"
+#include "gtk/css/gtkcssvariablevalueprivate.h"
 
 
 G_BEGIN_DECLS
@@ -37,6 +39,7 @@ typedef struct {
 struct _GtkCssLookup {
   GtkBitmask *set_values;
   GtkCssLookupValue  values[GTK_CSS_PROPERTY_N_PROPERTIES];
+  GHashTable *custom_values;
 };
 
 void                    _gtk_css_lookup_init                    (GtkCssLookup               *lookup);
@@ -47,6 +50,9 @@ void                    _gtk_css_lookup_set                     (GtkCssLookup
                                                                  guint                       id,
                                                                  GtkCssSection              *section,
                                                                  GtkCssValue                *value);
+void                    _gtk_css_lookup_set_custom              (GtkCssLookup               *lookup,
+                                                                 int                         id,
+                                                                 GtkCssVariableValue        *value);
 
 static inline const GtkBitmask *
 _gtk_css_lookup_get_set_values (const GtkCssLookup *lookup)

gtk/gtkcssnode.c

@@ -445,9 +445,12 @@ gtk_css_node_real_update_style (GtkCssNode                   *cssnode,
     }
   else if (static_style != style && (change & GTK_CSS_CHANGE_TIMESTAMP))
     {
+      GtkCssNode *parent = gtk_css_node_get_parent (cssnode);
       new_style = gtk_css_animated_style_new_advance (GTK_CSS_ANIMATED_STYLE (style),
                                                       static_style,
-                                                      timestamp);
+                                                      parent ? gtk_css_node_get_style (parent) : NULL,
+                                                      timestamp,
+                                                      gtk_css_node_get_style_provider (cssnode));
     }
   else
     {

gtk/gtkcssnumbervalue.c

@@ -108,11 +108,12 @@ get_base_font_size_px (guint             property_id,
 }
 
 static GtkCssValue *
-gtk_css_value_number_compute (GtkCssValue      *number,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_value_number_compute (GtkCssValue       *number,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   double value;
 
@@ -130,7 +131,8 @@ gtk_css_value_number_compute (GtkCssValue      *number,
         {
           GtkCssValue *computed = _gtk_css_value_compute (number->calc.terms[i],
                                                           property_id, provider, style,
-                                                          parent_style);
+                                                          parent_style,
+                                                          variables);
           changed |= computed != number->calc.terms[i];
           new_values[i] = computed;
         }
@@ -366,38 +368,38 @@ gtk_css_dimension_value_new (double     value,
                              GtkCssUnit unit)
 {
   static GtkCssValue number_singletons[] = {
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_NUMBER, 0 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_NUMBER, 1 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_NUMBER, 96 }} }, /* DPI default */
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_NUMBER, 0 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_NUMBER, 1 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_NUMBER, 96 }} }, /* DPI default */
   };
   static GtkCssValue px_singletons[] = {
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 0 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 1 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 2 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 3 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 4 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 5 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 6 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 7 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 8 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 16 }} }, /* Icon size default */
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 32 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_PX, 64 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 0 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 1 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 2 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 3 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 4 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 5 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 6 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 7 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 8 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 16 }} }, /* Icon size default */
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 32 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PX, 64 }} },
   };
   static GtkCssValue percent_singletons[] = {
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE,  TYPE_DIMENSION, {{ GTK_CSS_PERCENT, 0 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PERCENT, 50 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PERCENT, 100 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE,  FALSE, TYPE_DIMENSION, {{ GTK_CSS_PERCENT, 0 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, FALSE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PERCENT, 50 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, FALSE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_PERCENT, 100 }} },
   };
   static GtkCssValue second_singletons[] = {
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_S, 0 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_S, 1 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_S, 0 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_S, 1 }} },
   };
   static GtkCssValue deg_singletons[] = {
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_DEG, 0 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_DEG, 90 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_DEG, 180 }} },
-    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, TYPE_DIMENSION, {{ GTK_CSS_DEG, 270 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_DEG, 0 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_DEG, 90 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_DEG, 180 }} },
+    { &GTK_CSS_VALUE_NUMBER, 1, TRUE, FALSE, TYPE_DIMENSION, {{ GTK_CSS_DEG, 270 }} },
   };
   GtkCssValue *result;
 

gtk/gtkcsspalettevalue.c

@@ -103,11 +103,12 @@ gtk_css_value_palette_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_palette_compute (GtkCssValue      *specified,
-                               guint             property_id,
-                               GtkStyleProvider *provider,
-                               GtkCssStyle      *style,
-                               GtkCssStyle      *parent_style)
+gtk_css_value_palette_compute (GtkCssValue       *specified,
+                               guint              property_id,
+                               GtkStyleProvider  *provider,
+                               GtkCssStyle       *style,
+                               GtkCssStyle       *parent_style,
+                               GtkCssVariableSet *variables)
 {
   GtkCssValue *computed_color;
   GtkCssValue *result;
@@ -120,7 +121,7 @@ gtk_css_value_palette_compute (GtkCssValue      *specified,
     {
       GtkCssValue *value = specified->color_values[i];
 
-      computed_color = _gtk_css_value_compute (value, property_id, provider, style, parent_style);
+      computed_color = _gtk_css_value_compute (value, property_id, provider, style, parent_style, variables);
       result->color_names[i] = g_strdup (specified->color_names[i]);
       result->color_values[i] = computed_color;
 

gtk/gtkcsspositionvalue.c

@@ -36,16 +36,17 @@ gtk_css_value_position_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_position_compute (GtkCssValue      *position,
-                                guint             property_id,
-                                GtkStyleProvider *provider,
-                                GtkCssStyle      *style,
-                                GtkCssStyle      *parent_style)
+gtk_css_value_position_compute (GtkCssValue       *position,
+                                guint              property_id,
+                                GtkStyleProvider  *provider,
+                                GtkCssStyle       *style,
+                                GtkCssStyle       *parent_style,
+                                GtkCssVariableSet *variables)
 {
   GtkCssValue *x, *y;
 
-  x = _gtk_css_value_compute (position->x, property_id, provider, style, parent_style);
-  y = _gtk_css_value_compute (position->y, property_id, provider, style, parent_style);
+  x = _gtk_css_value_compute (position->x, property_id, provider, style, parent_style, variables);
+  y = _gtk_css_value_compute (position->y, property_id, provider, style, parent_style, variables);
   if (x == position->x && y == position->y)
     {
       _gtk_css_value_unref (x);

gtk/gtkcssprovider.c

@@ -22,10 +22,13 @@
 #include <gtk/css/gtkcss.h>
 #include "gtk/css/gtkcsstokenizerprivate.h"
 #include "gtk/css/gtkcssparserprivate.h"
+#include "gtk/css/gtkcssvariablevalueprivate.h"
 #include "gtkbitmaskprivate.h"
 #include "gtkcssarrayvalueprivate.h"
 #include "gtkcsscolorvalueprivate.h"
+#include "gtkcsscustompropertypoolprivate.h"
 #include "gtkcsskeyframesprivate.h"
+#include "gtkcssreferencevalueprivate.h"
 #include "gtkcssselectorprivate.h"
 #include "gtkcssshorthandpropertyprivate.h"
 #include "gtksettingsprivate.h"
@@ -113,6 +116,7 @@ struct GtkCssRuleset
   PropertyValue *styles;
   guint n_styles;
   guint owns_styles : 1;
+  GHashTable *custom_properties;
 };
 
 struct _GtkCssScanner
@@ -133,6 +137,7 @@ struct _GtkCssProviderPrivate
   GtkCssSelectorTree *tree;
   GResource *resource;
   char *path;
+  GBytes *bytes; /* *no* reference */
 };
 
 enum {
@@ -270,6 +275,8 @@ gtk_css_ruleset_clear (GtkCssRuleset *ruleset)
 	    gtk_css_section_unref (ruleset->styles[i].section);
         }
       g_free (ruleset->styles);
+      if (ruleset->custom_properties)
+        g_hash_table_unref (ruleset->custom_properties);
     }
   if (ruleset->selector)
     _gtk_css_selector_free (ruleset->selector);
@@ -285,7 +292,7 @@ gtk_css_ruleset_add (GtkCssRuleset       *ruleset,
 {
   guint i;
 
-  g_return_if_fail (ruleset->owns_styles || ruleset->n_styles == 0);
+  g_return_if_fail (ruleset->owns_styles || (ruleset->n_styles == 0 && ruleset->custom_properties == NULL));
 
   ruleset->owns_styles = TRUE;
 
@@ -315,6 +322,39 @@ gtk_css_ruleset_add (GtkCssRuleset       *ruleset,
     ruleset->styles[i].section = NULL;
 }
 
+static void
+unref_custom_property_name (gpointer pointer)
+{
+  GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
+
+  gtk_css_custom_property_pool_unref (pool, GPOINTER_TO_INT (pointer));
+}
+
+static void
+gtk_css_ruleset_add_custom (GtkCssRuleset       *ruleset,
+                            const char          *name,
+                            GtkCssVariableValue *value)
+{
+  GtkCssCustomPropertyPool *pool;
+  int id;
+
+  g_return_if_fail (ruleset->owns_styles || (ruleset->n_styles == 0 && ruleset->custom_properties == NULL));
+
+  ruleset->owns_styles = TRUE;
+
+  if (ruleset->custom_properties == NULL)
+    {
+      ruleset->custom_properties = g_hash_table_new_full (g_direct_hash, g_direct_equal,
+                                                          unref_custom_property_name,
+                                                          (GDestroyNotify) gtk_css_variable_value_unref);
+    }
+
+  pool = gtk_css_custom_property_pool_get ();
+  id = gtk_css_custom_property_pool_add (pool, name);
+
+  g_hash_table_replace (ruleset->custom_properties, GINT_TO_POINTER (id), value);
+}
+
 static void
 gtk_css_scanner_destroy (GtkCssScanner *scanner)
 {
@@ -342,9 +382,10 @@ gtk_css_scanner_parser_error (GtkCssParser         *parser,
   GtkCssScanner *scanner = user_data;
   GtkCssSection *section;
 
-  section = gtk_css_section_new (gtk_css_parser_get_file (parser),
-                                 start,
-                                 end);
+  section = gtk_css_section_new_with_bytes (gtk_css_parser_get_file (parser),
+                                            gtk_css_parser_get_bytes (parser),
+                                            start,
+                                            end);
 
   gtk_css_style_provider_emit_error (GTK_STYLE_PROVIDER (scanner->provider), section, error);
 
@@ -490,7 +531,7 @@ gtk_css_style_provider_lookup (GtkStyleProvider             *provider,
         {
           ruleset = gtk_css_selector_matches_get (&tree_rules, i);
 
-          if (ruleset->styles == NULL)
+          if (ruleset->styles == NULL && ruleset->custom_properties == NULL)
             continue;
 
           for (j = 0; j < ruleset->n_styles; j++)
@@ -506,6 +547,18 @@ gtk_css_style_provider_lookup (GtkStyleProvider             *provider,
                                    ruleset->styles[j].section,
                                    ruleset->styles[j].value);
             }
+
+          if (ruleset->custom_properties)
+            {
+              GHashTableIter iter;
+              gpointer id;
+              GtkCssVariableValue *value;
+
+              g_hash_table_iter_init (&iter, ruleset->custom_properties);
+
+              while (g_hash_table_iter_next (&iter, &id, (gpointer) &value))
+                _gtk_css_lookup_set_custom (lookup, GPOINTER_TO_INT (id), value);
+            }
         }
     }
   gtk_css_selector_matches_clear (&tree_rules);
@@ -514,6 +567,16 @@ gtk_css_style_provider_lookup (GtkStyleProvider             *provider,
     *change = gtk_css_selector_tree_get_change_all (priv->tree, filter, node);
 }
 
+static gboolean
+gtk_css_style_provider_has_section (GtkStyleProvider *provider,
+                                    GtkCssSection    *section)
+{
+  GtkCssProvider *self = GTK_CSS_PROVIDER (provider);
+  GtkCssProviderPrivate *priv = gtk_css_provider_get_instance_private (self);
+
+  return priv->bytes == gtk_css_section_get_bytes (section);
+}
+
 static void
 gtk_css_style_provider_iface_init (GtkStyleProviderInterface *iface)
 {
@@ -521,6 +584,7 @@ gtk_css_style_provider_iface_init (GtkStyleProviderInterface *iface)
   iface->get_keyframes = gtk_css_style_provider_get_keyframes;
   iface->lookup = gtk_css_style_provider_lookup;
   iface->emit_error = gtk_css_style_provider_emit_error;
+  iface->has_section = gtk_css_style_provider_has_section;
 }
 
 static void
@@ -572,7 +636,7 @@ css_provider_commit (GtkCssProvider  *css_provider,
   GtkCssProviderPrivate *priv = gtk_css_provider_get_instance_private (css_provider);
   guint i;
 
-  if (ruleset->styles == NULL)
+  if (ruleset->styles == NULL && ruleset->custom_properties == NULL)
     {
       for (i = 0; i < gtk_css_selectors_get_size (selectors); i++)
         _gtk_css_selector_free (gtk_css_selectors_get (selectors, i));
@@ -814,6 +878,49 @@ parse_declaration (GtkCssScanner *scanner,
   if (name == NULL)
     goto out;
 
+  /* This is a custom property */
+  if (name[0] == '-' && name[1] == '-')
+    {
+      GtkCssVariableValue *value;
+      GtkCssLocation start_location;
+      GtkCssSection *section;
+
+      if (!gtk_css_parser_try_token (scanner->parser, GTK_CSS_TOKEN_COLON))
+        {
+          gtk_css_parser_error_syntax (scanner->parser, "Expected ':'");
+          goto out;
+        }
+
+      gtk_css_parser_skip_whitespace (scanner->parser);
+
+      if (gtk_keep_css_sections)
+        start_location = *gtk_css_parser_get_start_location (scanner->parser);
+
+      value = gtk_css_parser_parse_value_into_token_stream (scanner->parser);
+      if (value == NULL)
+        goto out;
+
+      if (gtk_keep_css_sections)
+        {
+          section = gtk_css_section_new_with_bytes (gtk_css_parser_get_file (scanner->parser),
+                                                    gtk_css_parser_get_bytes (scanner->parser),
+                                                    &start_location,
+                                                    gtk_css_parser_get_start_location (scanner->parser));
+        }
+      else
+        section = NULL;
+
+      if (section != NULL)
+        {
+          gtk_css_variable_value_set_section (value, section);
+          gtk_css_section_unref (section);
+        }
+
+      gtk_css_ruleset_add_custom (ruleset, name, value);
+
+      goto out;
+    }
+
   property = _gtk_style_property_lookup (name);
 
   if (property)
@@ -827,22 +934,88 @@ parse_declaration (GtkCssScanner *scanner,
           goto out;
         }
 
-      value = _gtk_style_property_parse_value (property, scanner->parser);
-
-      if (value == NULL)
-        goto out;
-
-      if (!gtk_css_parser_has_token (scanner->parser, GTK_CSS_TOKEN_EOF))
+      if (gtk_css_parser_has_references (scanner->parser))
         {
-          gtk_css_parser_error_syntax (scanner->parser, "Junk at end of value for %s", property->name);
-          goto out;
+          GtkCssLocation start_location;
+          GtkCssVariableValue *var_value;
+
+          gtk_css_parser_skip_whitespace (scanner->parser);
+
+          if (gtk_keep_css_sections)
+            start_location = *gtk_css_parser_get_start_location (scanner->parser);
+
+          var_value = gtk_css_parser_parse_value_into_token_stream (scanner->parser);
+          if (var_value == NULL)
+            goto out;
+
+          if (gtk_keep_css_sections)
+            section = gtk_css_section_new_with_bytes (gtk_css_parser_get_file (scanner->parser),
+                                                      gtk_css_parser_get_bytes (scanner->parser),
+                                                      &start_location,
+                                                      gtk_css_parser_get_start_location (scanner->parser));
+          else
+            section = NULL;
+
+          if (section != NULL)
+            {
+              gtk_css_variable_value_set_section (var_value, section);
+              gtk_css_section_unref (section);
+            }
+
+          if (GTK_IS_CSS_SHORTHAND_PROPERTY (property))
+            {
+              GtkCssShorthandProperty *shorthand = GTK_CSS_SHORTHAND_PROPERTY (property);
+              guint i, n;
+              GtkCssValue **values;
+
+              n = _gtk_css_shorthand_property_get_n_subproperties (shorthand);
+
+              values = g_new (GtkCssValue *, n);
+
+              for (i = 0; i < n; i++)
+                {
+                  GtkCssValue *child =
+                    _gtk_css_reference_value_new (property,
+                                                  var_value,
+                                                  gtk_css_parser_get_file (scanner->parser));
+                  _gtk_css_reference_value_set_subproperty (child, i);
+
+                  values[i] = _gtk_css_array_value_get_nth (child, i);
+                }
+
+              value = _gtk_css_array_value_new_from_array (values, n);
+              g_free (values);
+            }
+          else
+            {
+              value = _gtk_css_reference_value_new (property,
+                                                    var_value,
+                                                    gtk_css_parser_get_file (scanner->parser));
+            }
+
+          gtk_css_variable_value_unref (var_value);
+        }
+      else
+        {
+          value = _gtk_style_property_parse_value (property, scanner->parser);
+
+          if (value == NULL)
+            goto out;
+
+          if (!gtk_css_parser_has_token (scanner->parser, GTK_CSS_TOKEN_EOF))
+            {
+              gtk_css_parser_error_syntax (scanner->parser, "Junk at end of value for %s", property->name);
+              gtk_css_value_unref (value);
+              goto out;
+            }
         }
 
       if (gtk_keep_css_sections)
         {
-          section = gtk_css_section_new (gtk_css_parser_get_file (scanner->parser),
-                                         gtk_css_parser_get_block_location (scanner->parser),
-                                         gtk_css_parser_get_end_location (scanner->parser));
+          section = gtk_css_section_new_with_bytes (gtk_css_parser_get_file (scanner->parser),
+                                                    gtk_css_parser_get_bytes (scanner->parser),
+                                                    gtk_css_parser_get_block_location (scanner->parser),
+                                                    gtk_css_parser_get_end_location (scanner->parser));
         }
       else
         section = NULL;
@@ -1025,6 +1198,7 @@ gtk_css_provider_load_internal (GtkCssProvider *self,
                                 GFile          *file,
                                 GBytes         *bytes)
 {
+  GtkCssProviderPrivate *priv = gtk_css_provider_get_instance_private (self);
   gint64 before G_GNUC_UNUSED;
 
   before = GDK_PROFILER_CURRENT_TIME;
@@ -1059,6 +1233,8 @@ gtk_css_provider_load_internal (GtkCssProvider *self,
         }
     }
 
+  priv->bytes = bytes;
+
   if (bytes)
     {
       GtkCssScanner *scanner;
@@ -1112,7 +1288,7 @@ gtk_css_provider_load_from_data (GtkCssProvider  *css_provider,
   if (length < 0)
     length = strlen (data);
 
-  bytes = g_bytes_new_static (data, length);
+  bytes = g_bytes_new (data, length);
 
   gtk_css_provider_load_from_bytes (css_provider, bytes);
 
@@ -1139,7 +1315,7 @@ gtk_css_provider_load_from_string (GtkCssProvider *css_provider,
   g_return_if_fail (GTK_IS_CSS_PROVIDER (css_provider));
   g_return_if_fail (string != NULL);
 
-  bytes = g_bytes_new_static (string, strlen (string));
+  bytes = g_bytes_new (string, strlen (string));
 
   gtk_css_provider_load_from_bytes (css_provider, bytes);
 
@@ -1473,6 +1649,20 @@ compare_properties (gconstpointer a, gconstpointer b, gpointer style)
                  _gtk_style_property_get_name (GTK_STYLE_PROPERTY (styles[*ub].property)));
 }
 
+static int
+compare_custom_properties (gconstpointer a, gconstpointer b, gpointer user_data)
+{
+  GtkCssCustomPropertyPool *pool = user_data;
+  int id1 = GPOINTER_TO_INT (*((const int *) a));
+  int id2 = GPOINTER_TO_INT (*((const int *) b));
+  const char *name1, *name2;
+
+  name1 = gtk_css_custom_property_pool_get_name (pool, id1);
+  name2 = gtk_css_custom_property_pool_get_name (pool, id2);
+
+  return strcmp (name1, name2);
+}
+
 static void
 gtk_css_ruleset_print (const GtkCssRuleset *ruleset,
                        GString             *str)
@@ -1506,6 +1696,31 @@ gtk_css_ruleset_print (const GtkCssRuleset *ruleset,
       g_free (sorted);
     }
 
+  if (ruleset->custom_properties)
+    {
+      GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
+      GPtrArray *keys;
+
+      keys = g_hash_table_get_keys_as_ptr_array (ruleset->custom_properties);
+      g_ptr_array_sort_with_data (keys, compare_custom_properties, pool);
+
+      for (i = 0; i < keys->len; i++)
+        {
+          int id = GPOINTER_TO_INT (g_ptr_array_index (keys, i));
+          const char *name = gtk_css_custom_property_pool_get_name (pool, id);
+          GtkCssVariableValue *value = g_hash_table_lookup (ruleset->custom_properties,
+                                                            GINT_TO_POINTER (id));
+
+          g_string_append (str, "  ");
+          g_string_append (str, name);
+          g_string_append (str, ": ");
+          gtk_css_variable_value_print (value, str);
+          g_string_append (str, ";\n");
+        }
+
+      g_ptr_array_unref (keys);
+    }
+
   g_string_append (str, "}\n");
 }
 
@@ -1598,4 +1813,3 @@ gtk_css_provider_to_string (GtkCssProvider *provider)
 
   return g_string_free (str, FALSE);
 }
-

gtk/gtkcssreferencevalue.c

@@ -0,0 +1,377 @@
+/*
+ * Copyright (C) 2023 GNOME Foundation Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alice Mikhaylenko <alicem@gnome.org>
+ */
+
+#include "config.h"
+
+#include "gtkcssreferencevalueprivate.h"
+
+#include "gtkcssarrayvalueprivate.h"
+#include "gtkcsscustompropertypoolprivate.h"
+#include "gtkcssshorthandpropertyprivate.h"
+#include "gtkcssstyleprivate.h"
+#include "gtkcssunsetvalueprivate.h"
+#include "gtkcssvalueprivate.h"
+#include "gtkstyleproviderprivate.h"
+
+#define GDK_ARRAY_NAME gtk_css_refs
+#define GDK_ARRAY_TYPE_NAME GtkCssRefs
+#define GDK_ARRAY_ELEMENT_TYPE gpointer
+#define GDK_ARAY_PREALLOC 32
+#define GDK_ARRAY_NO_MEMSET 1
+#include "gdk/gdkarrayimpl.c"
+
+#define MAX_TOKEN_LENGTH 65536
+
+typedef enum {
+  RESOLVE_SUCCESS,
+  RESOLVE_INVALID,
+  RESOLVE_ANIMATION_TAINTED,
+} ResolveResult;
+
+struct _GtkCssValue {
+  GTK_CSS_VALUE_BASE
+
+  GtkStyleProperty *property;
+  GtkCssVariableValue *value;
+  GFile *file;
+  guint subproperty;
+};
+
+static void
+gtk_css_value_reference_free (GtkCssValue *value)
+{
+  gtk_css_variable_value_unref (value->value);
+  if (value->file)
+    g_object_unref (value->file);
+}
+
+static ResolveResult
+resolve_references_do (GtkCssVariableValue *value,
+                       guint                property_id,
+                       GtkCssVariableSet   *style_variables,
+                       GtkCssVariableSet   *keyframes_variables,
+                       gboolean             root,
+                       GtkCssRefs          *refs,
+                       gsize               *out_length,
+                       gsize               *out_n_refs)
+{
+  GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
+  gsize i;
+  gsize length = value->length;
+  gsize n_refs = 0;
+  ResolveResult ret = RESOLVE_SUCCESS;
+
+  if (value->is_animation_tainted)
+    {
+      GtkCssStyleProperty *prop = _gtk_css_style_property_lookup_by_id (property_id);
+
+      if (!_gtk_css_style_property_is_animated (prop))
+        {
+          /* Animation-tainted variables make other variables that reference
+           * them animation-tainted too, so unlike regular invalid variables it
+           * propagates to the root. For example, if --test is animation-tainted,
+           * --test2: var(--test, fallback1); prop: var(--test2, fallback2); will\
+           * resolve to fallback2 and _not_ to fallback1. So we'll propagate it
+           * up until the root, and treat it same as invalid there instead. */
+          ret = RESOLVE_ANIMATION_TAINTED;
+          goto error;
+        }
+    }
+
+  if (value->is_invalid)
+    {
+      ret = RESOLVE_INVALID;
+      goto error;
+    }
+
+  if (!root)
+    {
+      n_refs += 1;
+      gtk_css_refs_append (refs, value);
+    }
+
+  for (i = 0; i < value->n_references; i++)
+    {
+      GtkCssVariableValueReference *ref = &value->references[i];
+      int id = gtk_css_custom_property_pool_lookup (pool, ref->name);
+      GtkCssVariableValue *var_value = NULL;
+      gsize var_length, var_refs;
+      GtkCssVariableSet *source = style_variables;
+      ResolveResult result = RESOLVE_INVALID;
+
+      if (keyframes_variables)
+        var_value = gtk_css_variable_set_lookup (keyframes_variables, id, NULL);
+
+      if (!var_value && style_variables)
+        var_value = gtk_css_variable_set_lookup (style_variables, id, &source);
+
+      if (var_value)
+        {
+          result = resolve_references_do (var_value, property_id, source,
+                                          keyframes_variables, FALSE,
+                                          refs, &var_length, &var_refs);
+
+          if (root && result == RESOLVE_ANIMATION_TAINTED)
+            result = RESOLVE_INVALID;
+        }
+
+      if (result == RESOLVE_INVALID)
+        {
+          if (ref->fallback)
+            {
+              result = resolve_references_do (ref->fallback, property_id,
+                                              style_variables, keyframes_variables,
+                                              FALSE, refs, &var_length, &var_refs);
+
+              if (root && result == RESOLVE_ANIMATION_TAINTED)
+                result = RESOLVE_INVALID;
+            }
+
+          if (result != RESOLVE_SUCCESS)
+            {
+              ret = result;
+              goto error;
+            }
+        }
+      else if (result == RESOLVE_ANIMATION_TAINTED)
+        {
+          ret = RESOLVE_ANIMATION_TAINTED;
+          goto error;
+        }
+
+      length += var_length - ref->length;
+      n_refs += var_refs;
+
+      if (length > MAX_TOKEN_LENGTH)
+        {
+          ret = RESOLVE_INVALID;
+          goto error;
+        }
+    }
+
+  if (out_length)
+    *out_length = length;
+
+  if (out_n_refs)
+    *out_n_refs = n_refs;
+
+  return ret;
+
+error:
+  /* Remove the references we added as if nothing happened */
+  gtk_css_refs_splice (refs, gtk_css_refs_get_size (refs) - n_refs, n_refs, TRUE, NULL, 0);
+
+  if (out_length)
+    *out_length = 0;
+
+  if (out_n_refs)
+    *out_n_refs = 0;
+
+  return ret;
+}
+
+static void
+resolve_references (GtkCssVariableValue *input,
+                    guint                property_id,
+                    GtkCssStyle         *style,
+                    GtkCssVariableSet   *keyframes_variables,
+                    GtkCssRefs          *refs)
+{
+  if (resolve_references_do (input, property_id, style->variables,
+                             keyframes_variables, TRUE, refs,
+                             NULL, NULL) != RESOLVE_SUCCESS)
+    {
+      gtk_css_refs_clear (refs);
+    }
+}
+
+static void
+parser_error (GtkCssParser         *parser,
+              const GtkCssLocation *start,
+              const GtkCssLocation *end,
+              const GError         *error,
+              gpointer              user_data)
+{
+  GtkStyleProvider *provider = user_data;
+  GError *new_error = NULL;
+  GtkCssVariableValue **vars;
+  char **names;
+  gsize n_vars;
+
+  gtk_css_parser_get_expanding_variables (parser, &vars, &names, &n_vars);
+
+  if (n_vars > 0)
+    {
+      for (int i = 0; i < n_vars; i++)
+        {
+          if (names[i + 1])
+            g_set_error (&new_error,
+                         GTK_CSS_PARSER_ERROR, GTK_CSS_PARSER_ERROR_UNKNOWN_VALUE,
+                         "While expanding %s: %s", names[i + 1], error->message);
+          else
+            g_set_error_literal (&new_error,
+                                 GTK_CSS_PARSER_ERROR, GTK_CSS_PARSER_ERROR_UNKNOWN_VALUE,
+                                 error->message);
+          gtk_style_provider_emit_error (provider, vars[i]->section, new_error);
+          g_clear_error (&new_error);
+        }
+
+      for (int i = 0; i < n_vars; i++)
+        {
+          if (vars[i])
+            gtk_css_variable_value_unref (vars[i]);
+          g_free (names[i]);
+        }
+
+      g_free (vars);
+      g_free (names);
+    }
+}
+
+static GtkCssValue *
+gtk_css_value_reference_compute (GtkCssValue       *value,
+                                 guint              property_id,
+                                 GtkStyleProvider  *provider,
+                                 GtkCssStyle       *style,
+                                 GtkCssStyle       *parent_style,
+                                 GtkCssVariableSet *variables)
+{
+  GtkCssValue *result = NULL, *computed;
+  GtkCssRefs refs;
+
+  gtk_css_refs_init (&refs);
+
+  resolve_references (value->value, property_id, style, variables, &refs);
+
+  if (gtk_css_refs_get_size (&refs) > 0)
+    {
+      const GtkCssToken *token;
+
+      GtkCssParser *value_parser =
+        gtk_css_parser_new_for_token_stream (value->value,
+                                             value->file,
+                                             (GtkCssVariableValue **) refs.start,
+                                             gtk_css_refs_get_size (&refs),
+                                             parser_error, provider, NULL);
+
+      result = _gtk_style_property_parse_value (value->property, value_parser);
+      token = gtk_css_parser_peek_token (value_parser);
+      if (!gtk_css_token_is (token, GTK_CSS_TOKEN_EOF))
+        {
+          char *junk;
+
+          junk = gtk_css_token_to_string (token);
+          gtk_css_parser_error_syntax (value_parser,
+                                       "Junk at end of %s value: %s",
+                                       value->property->name, junk);
+          g_free (junk);
+
+          g_clear_pointer (&result, gtk_css_value_unref);
+        }
+      gtk_css_parser_unref (value_parser);
+    }
+
+  gtk_css_refs_clear (&refs);
+
+  if (result == NULL)
+    result = _gtk_css_unset_value_new ();
+
+  if (GTK_IS_CSS_SHORTHAND_PROPERTY (value->property))
+    {
+      GtkCssValue *sub = gtk_css_value_ref (_gtk_css_array_value_get_nth (result, value->subproperty));
+      gtk_css_value_unref (result);
+      result = sub;
+    }
+
+  computed = _gtk_css_value_compute (result,
+                                     property_id,
+                                     provider,
+                                     style,
+                                     parent_style,
+                                     variables);
+  computed->is_computed = TRUE;
+
+  gtk_css_value_unref (result);
+
+  return computed;
+}
+
+static gboolean
+gtk_css_value_reference_equal (const GtkCssValue *value1,
+                               const GtkCssValue *value2)
+{
+  return FALSE;
+}
+
+static GtkCssValue *
+gtk_css_value_reference_transition (GtkCssValue *start,
+                                    GtkCssValue *end,
+                                    guint        property_id,
+                                    double       progress)
+{
+  return NULL;
+}
+
+static void
+gtk_css_value_reference_print (const GtkCssValue *value,
+                               GString           *string)
+{
+  gtk_css_variable_value_print (value->value, string);
+}
+
+static const GtkCssValueClass GTK_CSS_VALUE_REFERENCE = {
+  "GtkCssReferenceValue",
+  gtk_css_value_reference_free,
+  gtk_css_value_reference_compute,
+  gtk_css_value_reference_equal,
+  gtk_css_value_reference_transition,
+  NULL,
+  NULL,
+  gtk_css_value_reference_print
+};
+
+GtkCssValue *
+_gtk_css_reference_value_new (GtkStyleProperty    *property,
+                              GtkCssVariableValue *value,
+                              GFile               *file)
+{
+  GtkCssValue *result;
+
+  result = _gtk_css_value_new (GtkCssValue, &GTK_CSS_VALUE_REFERENCE);
+  result->property = property;
+  result->value = gtk_css_variable_value_ref (value);
+  result->contains_variables = TRUE;
+
+  if (file)
+    result->file = g_object_ref (file);
+  else
+    result->file = NULL;
+
+  return result;
+}
+
+void
+_gtk_css_reference_value_set_subproperty (GtkCssValue *value,
+                                          guint        property)
+{
+  g_assert (GTK_IS_CSS_SHORTHAND_PROPERTY (value->property));
+
+  value->subproperty = property;
+}
+

gtk/gtkcssreferencevalueprivate.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2023 GNOME Foundation Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alice Mikhaylenko <alicem@gnome.org>
+ */
+
+#pragma once
+
+#include <gtk/css/gtkcss.h>
+#include "gtkcssvalueprivate.h"
+#include "gtkstylepropertyprivate.h"
+#include "css/gtkcssvariablevalueprivate.h"
+
+G_BEGIN_DECLS
+
+GtkCssValue *_gtk_css_reference_value_new             (GtkStyleProperty    *property,
+                                                       GtkCssVariableValue *value,
+                                                       GFile               *file);
+void         _gtk_css_reference_value_set_subproperty (GtkCssValue         *value,
+                                                       guint                property);
+
+G_END_DECLS

gtk/gtkcssrepeatvalue.c

@@ -34,11 +34,12 @@ gtk_css_value_repeat_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_repeat_compute (GtkCssValue      *value,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_value_repeat_compute (GtkCssValue       *value,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   return _gtk_css_value_ref (value);
 }
@@ -140,28 +141,28 @@ static struct {
   GtkCssValue values[4];
 } background_repeat_values[4] = {
   { "no-repeat",
-  { { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_NO_REPEAT, GTK_CSS_REPEAT_STYLE_NO_REPEAT },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_NO_REPEAT, GTK_CSS_REPEAT_STYLE_REPEAT    },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_NO_REPEAT, GTK_CSS_REPEAT_STYLE_ROUND     },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_NO_REPEAT, GTK_CSS_REPEAT_STYLE_SPACE     }
+  { { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_NO_REPEAT, GTK_CSS_REPEAT_STYLE_NO_REPEAT },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_NO_REPEAT, GTK_CSS_REPEAT_STYLE_REPEAT    },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_NO_REPEAT, GTK_CSS_REPEAT_STYLE_ROUND     },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_NO_REPEAT, GTK_CSS_REPEAT_STYLE_SPACE     }
   } },
   { "repeat",
-  { { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_REPEAT,    GTK_CSS_REPEAT_STYLE_NO_REPEAT },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_REPEAT,    GTK_CSS_REPEAT_STYLE_REPEAT    },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_REPEAT,    GTK_CSS_REPEAT_STYLE_ROUND     },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_REPEAT,    GTK_CSS_REPEAT_STYLE_SPACE     }
+  { { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_REPEAT,    GTK_CSS_REPEAT_STYLE_NO_REPEAT },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_REPEAT,    GTK_CSS_REPEAT_STYLE_REPEAT    },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_REPEAT,    GTK_CSS_REPEAT_STYLE_ROUND     },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_REPEAT,    GTK_CSS_REPEAT_STYLE_SPACE     }
   } }, 
   { "round",
-  { { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_ROUND,     GTK_CSS_REPEAT_STYLE_NO_REPEAT },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_ROUND,     GTK_CSS_REPEAT_STYLE_REPEAT    },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_ROUND,     GTK_CSS_REPEAT_STYLE_ROUND     },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_ROUND,     GTK_CSS_REPEAT_STYLE_SPACE     }
+  { { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_ROUND,     GTK_CSS_REPEAT_STYLE_NO_REPEAT },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_ROUND,     GTK_CSS_REPEAT_STYLE_REPEAT    },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_ROUND,     GTK_CSS_REPEAT_STYLE_ROUND     },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_ROUND,     GTK_CSS_REPEAT_STYLE_SPACE     }
   } }, 
   { "space",
-  { { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_SPACE,     GTK_CSS_REPEAT_STYLE_NO_REPEAT },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_SPACE,     GTK_CSS_REPEAT_STYLE_REPEAT    },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_SPACE,     GTK_CSS_REPEAT_STYLE_ROUND     },
-    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_SPACE,     GTK_CSS_REPEAT_STYLE_SPACE     }
+  { { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_SPACE,     GTK_CSS_REPEAT_STYLE_NO_REPEAT },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_SPACE,     GTK_CSS_REPEAT_STYLE_REPEAT    },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_SPACE,     GTK_CSS_REPEAT_STYLE_ROUND     },
+    { &GTK_CSS_VALUE_BACKGROUND_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_SPACE,     GTK_CSS_REPEAT_STYLE_SPACE     }
   } }
 };
 
@@ -234,28 +235,28 @@ static struct {
   GtkCssValue values[4];
 } border_repeat_values[4] = {
   { "stretch",
-  { { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_STRETCH, GTK_CSS_REPEAT_STYLE_STRETCH },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_STRETCH, GTK_CSS_REPEAT_STYLE_REPEAT  },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_STRETCH, GTK_CSS_REPEAT_STYLE_ROUND   },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_STRETCH, GTK_CSS_REPEAT_STYLE_SPACE   }
+  { { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_STRETCH, GTK_CSS_REPEAT_STYLE_STRETCH },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_STRETCH, GTK_CSS_REPEAT_STYLE_REPEAT  },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_STRETCH, GTK_CSS_REPEAT_STYLE_ROUND   },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_STRETCH, GTK_CSS_REPEAT_STYLE_SPACE   }
   } },
   { "repeat",
-  { { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_REPEAT,  GTK_CSS_REPEAT_STYLE_STRETCH },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_REPEAT,  GTK_CSS_REPEAT_STYLE_REPEAT  },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_REPEAT,  GTK_CSS_REPEAT_STYLE_ROUND   },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_REPEAT,  GTK_CSS_REPEAT_STYLE_SPACE   }
+  { { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_REPEAT,  GTK_CSS_REPEAT_STYLE_STRETCH },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_REPEAT,  GTK_CSS_REPEAT_STYLE_REPEAT  },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_REPEAT,  GTK_CSS_REPEAT_STYLE_ROUND   },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_REPEAT,  GTK_CSS_REPEAT_STYLE_SPACE   }
   } }, 
   { "round",
-  { { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_ROUND,   GTK_CSS_REPEAT_STYLE_STRETCH },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_ROUND,   GTK_CSS_REPEAT_STYLE_REPEAT  },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_ROUND,   GTK_CSS_REPEAT_STYLE_ROUND   },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_ROUND,   GTK_CSS_REPEAT_STYLE_SPACE   }
+  { { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_ROUND,   GTK_CSS_REPEAT_STYLE_STRETCH },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_ROUND,   GTK_CSS_REPEAT_STYLE_REPEAT  },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_ROUND,   GTK_CSS_REPEAT_STYLE_ROUND   },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_ROUND,   GTK_CSS_REPEAT_STYLE_SPACE   }
   } }, 
   { "space",
-  { { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_SPACE,   GTK_CSS_REPEAT_STYLE_STRETCH },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_SPACE,   GTK_CSS_REPEAT_STYLE_REPEAT  },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_SPACE,   GTK_CSS_REPEAT_STYLE_ROUND   },
-    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, GTK_CSS_REPEAT_STYLE_SPACE,   GTK_CSS_REPEAT_STYLE_SPACE   }
+  { { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_SPACE,   GTK_CSS_REPEAT_STYLE_STRETCH },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_SPACE,   GTK_CSS_REPEAT_STYLE_REPEAT  },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_SPACE,   GTK_CSS_REPEAT_STYLE_ROUND   },
+    { &GTK_CSS_VALUE_BORDER_REPEAT, 1, TRUE, FALSE, GTK_CSS_REPEAT_STYLE_SPACE,   GTK_CSS_REPEAT_STYLE_SPACE   }
   } }
 };
 

gtk/gtkcssshadowvalue.c

@@ -113,11 +113,12 @@ gtk_css_value_shadow_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_shadow_compute (GtkCssValue      *value,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_value_shadow_compute (GtkCssValue       *value,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   guint i;
   ShadowValue *shadows;
@@ -128,11 +129,11 @@ gtk_css_value_shadow_compute (GtkCssValue      *value,
     {
       const ShadowValue *shadow = &value->shadows[i];
 
-      shadows[i].hoffset = _gtk_css_value_compute (shadow->hoffset, property_id, provider, style, parent_style);
-      shadows[i].voffset = _gtk_css_value_compute (shadow->voffset, property_id, provider, style, parent_style);
-      shadows[i].radius = _gtk_css_value_compute (shadow->radius, property_id, provider, style, parent_style);
-      shadows[i].spread = _gtk_css_value_compute (shadow->spread, property_id, provider, style, parent_style),
-      shadows[i].color = _gtk_css_value_compute (shadow->color, property_id, provider, style, parent_style);
+      shadows[i].hoffset = _gtk_css_value_compute (shadow->hoffset, property_id, provider, style, parent_style, variables);
+      shadows[i].voffset = _gtk_css_value_compute (shadow->voffset, property_id, provider, style, parent_style, variables);
+      shadows[i].radius = _gtk_css_value_compute (shadow->radius, property_id, provider, style, parent_style, variables);
+      shadows[i].spread = _gtk_css_value_compute (shadow->spread, property_id, provider, style, parent_style, variables),
+      shadows[i].color = _gtk_css_value_compute (shadow->color, property_id, provider, style, parent_style, variables);
       shadows[i].inset = shadow->inset;
     }
 

gtk/gtkcssstaticstyle.c

@@ -31,6 +31,7 @@
 #include "gtkcssstringvalueprivate.h"
 #include "gtkcssstylepropertyprivate.h"
 #include "gtkcsstransitionprivate.h"
+#include "gtkcssvaluesprivate.h"
 #include "gtkprivate.h"
 #include "gtksettings.h"
 #include "gtkstyleanimationprivate.h"
@@ -45,130 +46,6 @@ static void gtk_css_static_style_compute_value (GtkCssStaticStyle *style,
                                                 GtkCssValue       *specified,
                                                 GtkCssSection     *section);
 
-static const int core_props[] = {
-  GTK_CSS_PROPERTY_COLOR,
-  GTK_CSS_PROPERTY_DPI,
-  GTK_CSS_PROPERTY_FONT_SIZE,
-  GTK_CSS_PROPERTY_ICON_PALETTE
-};
-
-static const int background_props[] = {
-  GTK_CSS_PROPERTY_BACKGROUND_COLOR,
-  GTK_CSS_PROPERTY_BOX_SHADOW,
-  GTK_CSS_PROPERTY_BACKGROUND_CLIP,
-  GTK_CSS_PROPERTY_BACKGROUND_ORIGIN,
-  GTK_CSS_PROPERTY_BACKGROUND_SIZE,
-  GTK_CSS_PROPERTY_BACKGROUND_POSITION,
-  GTK_CSS_PROPERTY_BACKGROUND_REPEAT,
-  GTK_CSS_PROPERTY_BACKGROUND_IMAGE,
-  GTK_CSS_PROPERTY_BACKGROUND_BLEND_MODE
-};
-
-static const int border_props[] = {
-  GTK_CSS_PROPERTY_BORDER_TOP_STYLE,
-  GTK_CSS_PROPERTY_BORDER_TOP_WIDTH,
-  GTK_CSS_PROPERTY_BORDER_LEFT_STYLE,
-  GTK_CSS_PROPERTY_BORDER_LEFT_WIDTH,
-  GTK_CSS_PROPERTY_BORDER_BOTTOM_STYLE,
-  GTK_CSS_PROPERTY_BORDER_BOTTOM_WIDTH,
-  GTK_CSS_PROPERTY_BORDER_RIGHT_STYLE,
-  GTK_CSS_PROPERTY_BORDER_RIGHT_WIDTH,
-  GTK_CSS_PROPERTY_BORDER_TOP_LEFT_RADIUS,
-  GTK_CSS_PROPERTY_BORDER_TOP_RIGHT_RADIUS,
-  GTK_CSS_PROPERTY_BORDER_BOTTOM_RIGHT_RADIUS,
-  GTK_CSS_PROPERTY_BORDER_BOTTOM_LEFT_RADIUS,
-  GTK_CSS_PROPERTY_BORDER_TOP_COLOR,
-  GTK_CSS_PROPERTY_BORDER_RIGHT_COLOR,
-  GTK_CSS_PROPERTY_BORDER_BOTTOM_COLOR,
-  GTK_CSS_PROPERTY_BORDER_LEFT_COLOR,
-  GTK_CSS_PROPERTY_BORDER_IMAGE_SOURCE,
-  GTK_CSS_PROPERTY_BORDER_IMAGE_REPEAT,
-  GTK_CSS_PROPERTY_BORDER_IMAGE_SLICE,
-  GTK_CSS_PROPERTY_BORDER_IMAGE_WIDTH
-};
-
-static const int icon_props[] = {
-  GTK_CSS_PROPERTY_ICON_SIZE,
-  GTK_CSS_PROPERTY_ICON_SHADOW,
-  GTK_CSS_PROPERTY_ICON_STYLE,
-};
-
-static const int outline_props[] = {
-  GTK_CSS_PROPERTY_OUTLINE_STYLE,
-  GTK_CSS_PROPERTY_OUTLINE_WIDTH,
-  GTK_CSS_PROPERTY_OUTLINE_OFFSET,
-  GTK_CSS_PROPERTY_OUTLINE_COLOR,
-};
-
-static const int font_props[] = {
-  GTK_CSS_PROPERTY_FONT_FAMILY,
-  GTK_CSS_PROPERTY_FONT_STYLE,
-  GTK_CSS_PROPERTY_FONT_WEIGHT,
-  GTK_CSS_PROPERTY_FONT_STRETCH,
-  GTK_CSS_PROPERTY_LETTER_SPACING,
-  GTK_CSS_PROPERTY_TEXT_SHADOW,
-  GTK_CSS_PROPERTY_CARET_COLOR,
-  GTK_CSS_PROPERTY_SECONDARY_CARET_COLOR,
-  GTK_CSS_PROPERTY_FONT_FEATURE_SETTINGS,
-  GTK_CSS_PROPERTY_FONT_VARIATION_SETTINGS,
-  GTK_CSS_PROPERTY_LINE_HEIGHT,
-};
-static const int font_variant_props[] = {
-  GTK_CSS_PROPERTY_TEXT_DECORATION_LINE,
-  GTK_CSS_PROPERTY_TEXT_DECORATION_COLOR,
-  GTK_CSS_PROPERTY_TEXT_DECORATION_STYLE,
-  GTK_CSS_PROPERTY_TEXT_TRANSFORM,
-  GTK_CSS_PROPERTY_FONT_KERNING,
-  GTK_CSS_PROPERTY_FONT_VARIANT_LIGATURES,
-  GTK_CSS_PROPERTY_FONT_VARIANT_POSITION,
-  GTK_CSS_PROPERTY_FONT_VARIANT_CAPS,
-  GTK_CSS_PROPERTY_FONT_VARIANT_NUMERIC,
-  GTK_CSS_PROPERTY_FONT_VARIANT_ALTERNATES,
-  GTK_CSS_PROPERTY_FONT_VARIANT_EAST_ASIAN,
-};
-
-static const int animation_props[] = {
-  GTK_CSS_PROPERTY_ANIMATION_NAME,
-  GTK_CSS_PROPERTY_ANIMATION_DURATION,
-  GTK_CSS_PROPERTY_ANIMATION_TIMING_FUNCTION,
-  GTK_CSS_PROPERTY_ANIMATION_ITERATION_COUNT,
-  GTK_CSS_PROPERTY_ANIMATION_DIRECTION,
-  GTK_CSS_PROPERTY_ANIMATION_PLAY_STATE,
-  GTK_CSS_PROPERTY_ANIMATION_DELAY,
-  GTK_CSS_PROPERTY_ANIMATION_FILL_MODE,
-};
-
-static const int transition_props[] = {
-  GTK_CSS_PROPERTY_TRANSITION_PROPERTY,
-  GTK_CSS_PROPERTY_TRANSITION_DURATION,
-  GTK_CSS_PROPERTY_TRANSITION_TIMING_FUNCTION,
-  GTK_CSS_PROPERTY_TRANSITION_DELAY,
-};
-
-static const int size_props[] = {
-  GTK_CSS_PROPERTY_MARGIN_TOP,
-  GTK_CSS_PROPERTY_MARGIN_LEFT,
-  GTK_CSS_PROPERTY_MARGIN_BOTTOM,
-  GTK_CSS_PROPERTY_MARGIN_RIGHT,
-  GTK_CSS_PROPERTY_PADDING_TOP,
-  GTK_CSS_PROPERTY_PADDING_LEFT,
-  GTK_CSS_PROPERTY_PADDING_BOTTOM,
-  GTK_CSS_PROPERTY_PADDING_RIGHT,
-  GTK_CSS_PROPERTY_BORDER_SPACING,
-  GTK_CSS_PROPERTY_MIN_WIDTH,
-  GTK_CSS_PROPERTY_MIN_HEIGHT,
-};
-
-static const int other_props[] = {
-  GTK_CSS_PROPERTY_ICON_SOURCE,
-  GTK_CSS_PROPERTY_ICON_TRANSFORM,
-  GTK_CSS_PROPERTY_ICON_FILTER,
-  GTK_CSS_PROPERTY_TRANSFORM,
-  GTK_CSS_PROPERTY_TRANSFORM_ORIGIN,
-  GTK_CSS_PROPERTY_OPACITY,
-  GTK_CSS_PROPERTY_FILTER,
-};
-
 #define GET_VALUES(v) (GtkCssValue **)((guint8*)(v) + sizeof (GtkCssValues))
 
 #define DEFINE_VALUES(ENUM, TYPE, NAME) \
@@ -322,6 +199,12 @@ gtk_css_static_style_dispose (GObject *object)
       style->sections = NULL;
     }
 
+  if (style->original_values)
+    {
+      g_ptr_array_unref (style->original_values);
+      style->original_values = NULL;
+    }
+
   G_OBJECT_CLASS (gtk_css_static_style_parent_class)->dispose (object);
 }
 
@@ -331,6 +214,19 @@ gtk_css_static_style_get_static_style (GtkCssStyle *style)
   return (GtkCssStaticStyle *)style;
 }
 
+static GtkCssValue *
+gtk_css_static_style_get_original_value (GtkCssStyle *style,
+                                         guint        id)
+{
+  GtkCssStaticStyle *sstyle = GTK_CSS_STATIC_STYLE (style);
+
+  if (sstyle->original_values == NULL ||
+      id >= sstyle->original_values->len)
+    return NULL;
+
+  return g_ptr_array_index (sstyle->original_values, id);
+}
+
 static void
 gtk_css_static_style_class_init (GtkCssStaticStyleClass *klass)
 {
@@ -341,6 +237,7 @@ gtk_css_static_style_class_init (GtkCssStaticStyleClass *klass)
 
   style_class->get_section = gtk_css_static_style_get_section;
   style_class->get_static_style = gtk_css_static_style_get_static_style;
+  style_class->get_original_value = gtk_css_static_style_get_original_value;
 
   gtk_css_core_values_init ();
   gtk_css_background_values_init ();
@@ -369,6 +266,13 @@ maybe_unref_section (gpointer section)
     gtk_css_section_unref (section);
 }
 
+static void
+maybe_unref_value (gpointer value)
+{
+  if (value)
+    _gtk_css_value_unref (value);
+}
+
 static inline void
 gtk_css_take_value (GtkCssValue **variable,
                     GtkCssValue  *value)
@@ -382,6 +286,7 @@ static void
 gtk_css_static_style_set_value (GtkCssStaticStyle *sstyle,
                                 guint              id,
                                 GtkCssValue       *value,
+                                GtkCssValue       *original_value,
                                 GtkCssSection     *section)
 {
   GtkCssStyle *style = (GtkCssStyle *)sstyle;
@@ -684,6 +589,22 @@ gtk_css_static_style_set_value (GtkCssStaticStyle *sstyle,
         g_ptr_array_set_size (sstyle->sections, id + 1);
       g_ptr_array_index (sstyle->sections, id) = gtk_css_section_ref (section);
     }
+
+  if (sstyle->original_values && sstyle->original_values->len > id &&
+      g_ptr_array_index (sstyle->original_values, id))
+    {
+      _gtk_css_value_unref (g_ptr_array_index (sstyle->original_values, id));
+      g_ptr_array_index (sstyle->original_values, id) = NULL;
+    }
+
+  if (original_value)
+    {
+      if (sstyle->original_values == NULL)
+        sstyle->original_values = g_ptr_array_new_with_free_func (maybe_unref_value);
+      if (sstyle->original_values->len <= id)
+        g_ptr_array_set_size (sstyle->original_values, id + 1);
+      g_ptr_array_index (sstyle->original_values, id) = _gtk_css_value_ref (original_value);
+    }
 }
 
 static GtkCssStyle *default_style;
@@ -912,6 +833,32 @@ gtk_css_lookup_resolve (GtkCssLookup      *lookup,
   gtk_internal_return_if_fail (GTK_IS_CSS_STATIC_STYLE (style));
   gtk_internal_return_if_fail (parent_style == NULL || GTK_IS_CSS_STYLE (parent_style));
 
+  if (lookup->custom_values)
+    {
+      GHashTableIter iter;
+      gpointer id;
+      GtkCssVariableValue *value;
+
+      style->variables = gtk_css_variable_set_new ();
+
+      g_hash_table_iter_init (&iter, lookup->custom_values);
+
+      while (g_hash_table_iter_next (&iter, &id, (gpointer) &value))
+        gtk_css_variable_set_add (style->variables, GPOINTER_TO_INT (id), value);
+
+      gtk_css_variable_set_resolve_cycles (style->variables);
+
+      if (parent_style)
+        {
+          gtk_css_variable_set_set_parent (style->variables,
+                                           parent_style->variables);
+        }
+    }
+  else if (parent_style && parent_style->variables)
+    {
+      style->variables = gtk_css_variable_set_ref (parent_style->variables);
+    }
+
   if (_gtk_bitmask_is_empty (_gtk_css_lookup_get_set_values (lookup)))
     {
       style->background = (GtkCssBackgroundValues *)gtk_css_values_ref (gtk_css_background_initial_values);
@@ -1047,7 +994,7 @@ gtk_css_static_style_compute_value (GtkCssStaticStyle *style,
                                     GtkCssValue       *specified,
                                     GtkCssSection     *section)
 {
-  GtkCssValue *value;
+  GtkCssValue *value, *original_value;
   GtkBorderStyle border_style;
 
   gtk_internal_return_if_fail (id < GTK_CSS_PROPERTY_N_PROPERTIES);
@@ -1068,7 +1015,7 @@ gtk_css_static_style_compute_value (GtkCssStaticStyle *style,
         border_style = _gtk_css_border_style_value_get (gtk_css_style_get_value ((GtkCssStyle *)style, id - 1));
         if (border_style == GTK_BORDER_STYLE_NONE || border_style == GTK_BORDER_STYLE_HIDDEN)
           {
-            gtk_css_static_style_set_value (style, id, gtk_css_dimension_value_new (0, GTK_CSS_NUMBER), section);
+            gtk_css_static_style_set_value (style, id, gtk_css_dimension_value_new (0, GTK_CSS_NUMBER), NULL, section);
             return;
           }
         break;
@@ -1085,19 +1032,34 @@ gtk_css_static_style_compute_value (GtkCssStaticStyle *style,
    */
   if (specified)
     {
-      value = _gtk_css_value_compute (specified, id, provider, (GtkCssStyle *)style, parent_style);
+      value = _gtk_css_value_compute (specified, id, provider, (GtkCssStyle *)style, parent_style, NULL);
+
+      if (gtk_css_value_contains_variables (specified))
+        original_value = specified;
+      else
+        original_value = NULL;
     }
   else if (parent_style && _gtk_css_style_property_is_inherit (_gtk_css_style_property_lookup_by_id (id)))
     {
+      GtkCssValue *parent_original_value;
+
       /* Just take the style from the parent */
       value = _gtk_css_value_ref (gtk_css_style_get_value (parent_style, id));
+
+      parent_original_value = gtk_css_style_get_original_value (parent_style, id);
+
+      if (parent_original_value)
+        original_value = parent_original_value;
+      else
+        original_value = NULL;
     }
   else
     {
       value = _gtk_css_initial_value_new_compute (id, provider, (GtkCssStyle *)style, parent_style);
+      original_value = NULL;
     }
 
-  gtk_css_static_style_set_value (style, id, value, section);
+  gtk_css_static_style_set_value (style, id, value, original_value, section);
 }
 
 GtkCssChange
@@ -1107,3 +1069,15 @@ gtk_css_static_style_get_change (GtkCssStaticStyle *style)
 
   return style->change;
 }
+
+void
+gtk_css_custom_values_compute_changes_and_affects (GtkCssStyle    *style1,
+                                                   GtkCssStyle    *style2,
+                                                   GtkBitmask    **changes,
+                                                   GtkCssAffects  *affects)
+{
+  if (gtk_css_variable_set_equal (style1->variables, style2->variables))
+    return;
+
+  *changes = _gtk_bitmask_set (*changes, GTK_CSS_PROPERTY_CUSTOM, TRUE);
+}

gtk/gtkcssstaticstyleprivate.h

@@ -40,6 +40,7 @@ struct _GtkCssStaticStyle
   GtkCssStyle parent;
 
   GPtrArray             *sections;             /* sections the values are defined in */
+  GPtrArray             *original_values;
 
   GtkCssChange           change;               /* change as returned by value lookup */
 };

gtk/gtkcssstringvalue.c

@@ -35,11 +35,12 @@ gtk_css_value_string_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_string_compute (GtkCssValue      *value,
-                              guint             property_id,
-                              GtkStyleProvider *provider,
-                              GtkCssStyle      *style,
-                              GtkCssStyle      *parent_style)
+gtk_css_value_string_compute (GtkCssValue       *value,
+                              guint              property_id,
+                              GtkStyleProvider  *provider,
+                              GtkCssStyle       *style,
+                              GtkCssStyle       *parent_style,
+                              GtkCssVariableSet *variables)
 {
   return _gtk_css_value_ref (value);
 }
@@ -226,3 +227,4 @@ _gtk_css_ident_value_get (const GtkCssValue *value)
   return value->string;
 }
 
+

gtk/gtkcssstyle.c

@@ -24,6 +24,7 @@
 
 #include "gtkcssanimationprivate.h"
 #include "gtkcssarrayvalueprivate.h"
+#include "gtkcsscustompropertypoolprivate.h"
 #include "gtkcssenumvalueprivate.h"
 #include "gtkcssinheritvalueprivate.h"
 #include "gtkcssinitialvalueprivate.h"
@@ -74,6 +75,9 @@ gtk_css_style_finalize (GObject *object)
   gtk_css_values_unref ((GtkCssValues *)style->size);
   gtk_css_values_unref ((GtkCssValues *)style->other);
 
+  if (style->variables)
+    gtk_css_variable_set_unref (style->variables);
+
   G_OBJECT_CLASS (gtk_css_style_parent_class)->finalize (object);
 }
 
@@ -312,6 +316,15 @@ gtk_css_style_get_static_style (GtkCssStyle *style)
   return GTK_CSS_STYLE_GET_CLASS (style)->get_static_style (style);
 }
 
+GtkCssValue *
+gtk_css_style_get_original_value (GtkCssStyle *style,
+                                  guint        id)
+{
+  gtk_internal_return_val_if_fail (GTK_IS_CSS_STYLE (style), NULL);
+
+  return GTK_CSS_STYLE_GET_CLASS (style)->get_original_value (style, id);
+}
+
 /*
  * gtk_css_style_print:
  * @style: a `GtkCssStyle`
@@ -369,6 +382,43 @@ gtk_css_style_print (GtkCssStyle *style,
       retval = TRUE;
     }
 
+    if (style->variables)
+      {
+        GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
+        GArray *ids = gtk_css_variable_set_list_ids (style->variables);
+
+        for (i = 0; i < ids->len; i++)
+          {
+            int id = g_array_index (ids, int, i);
+            const char *name = gtk_css_custom_property_pool_get_name (pool, id);
+            GtkCssVariableSet *source;
+            GtkCssVariableValue *value = gtk_css_variable_set_lookup (style->variables, id, &source);
+
+            if (!value)
+              continue;
+
+            if (source != style->variables && skip_initial)
+              continue;
+
+            g_string_append_printf (string, "%*s%s: ", indent, "", name);
+            gtk_css_variable_value_print (value, string);
+            g_string_append_c (string, ';');
+
+            if (value->section)
+              {
+                g_string_append (string, " /* ");
+                gtk_css_section_print (value->section, string);
+                g_string_append (string, " */");
+              }
+
+            g_string_append_c (string, '\n');
+          }
+
+        retval = TRUE;
+
+        g_array_unref (ids);
+      }
+
   return retval;
 }
 
@@ -865,3 +915,22 @@ gtk_css_values_new (GtkCssValuesType type)
 
   return values;
 }
+
+GtkCssVariableValue *
+gtk_css_style_get_custom_property (GtkCssStyle *style,
+                                   int          id)
+{
+  if (style->variables)
+    return gtk_css_variable_set_lookup (style->variables, id, NULL);
+
+  return NULL;
+}
+
+GArray *
+gtk_css_style_list_custom_properties (GtkCssStyle *style)
+{
+  if (style->variables)
+    return gtk_css_variable_set_list_ids (style->variables);
+
+  return NULL;
+}

gtk/gtkcssstylechange.c

@@ -102,6 +102,12 @@ compute_change (GtkCssStyleChange *change)
                                                       change->new_style,
                                                       &change->changes,
                                                       &change->affects);
+
+  if (change->old_style->variables != change->new_style->variables)
+    gtk_css_custom_values_compute_changes_and_affects (change->old_style,
+                                                       change->new_style,
+                                                       &change->changes,
+                                                       &change->affects);
 }
 
 void

gtk/gtkcssstyleprivate.h

@@ -24,6 +24,8 @@
 
 #include "gtk/gtkbitmaskprivate.h"
 #include "gtk/gtkcssvalueprivate.h"
+#include "gtk/gtkcssvariablesetprivate.h"
+#include "gtk/css/gtkcssvariablevalueprivate.h"
 
 G_BEGIN_DECLS
 
@@ -232,6 +234,10 @@ struct _GtkCssStyle
   GtkCssTransitionValues  *transition;
   GtkCssSizeValues        *size;
   GtkCssOtherValues       *other;
+  GtkCssVariableSet       *variables;
+
+  GtkCssValue             *variable_values;
+  int                      n_variable_values;
 };
 
 struct _GtkCssStyleClass
@@ -246,6 +252,9 @@ struct _GtkCssStyleClass
   gboolean              (* is_static)                           (GtkCssStyle            *style);
 
   GtkCssStaticStyle *   (* get_static_style)                    (GtkCssStyle            *style);
+
+  GtkCssValue *         (* get_original_value)                  (GtkCssStyle            *style,
+                                                                 guint                   id);
 };
 
 GType                   gtk_css_style_get_type                  (void) G_GNUC_CONST;
@@ -257,6 +266,9 @@ GtkCssSection *         gtk_css_style_get_section               (GtkCssStyle
 gboolean                gtk_css_style_is_static                 (GtkCssStyle            *style) G_GNUC_PURE;
 GtkCssStaticStyle *     gtk_css_style_get_static_style          (GtkCssStyle            *style);
 
+GtkCssValue *           gtk_css_style_get_original_value        (GtkCssStyle            *style,
+                                                                 guint                   id) G_GNUC_PURE;
+
 char *                  gtk_css_style_to_string                 (GtkCssStyle            *style);
 gboolean                gtk_css_style_print                     (GtkCssStyle            *style,
                                                                  GString                *string,
@@ -271,6 +283,10 @@ PangoFontDescription *  gtk_css_style_get_pango_font            (GtkCssStyle
 void                    gtk_css_style_lookup_symbolic_colors    (GtkCssStyle            *style,
                                                                  GdkRGBA                 color_out[4]);
 
+GtkCssVariableValue *   gtk_css_style_get_custom_property       (GtkCssStyle            *style,
+                                                                 int                     id);
+GArray *                gtk_css_style_list_custom_properties    (GtkCssStyle            *style);
+
 GtkCssValues *gtk_css_values_new   (GtkCssValuesType  type);
 GtkCssValues *gtk_css_values_ref   (GtkCssValues     *values);
 void          gtk_css_values_unref (GtkCssValues     *values);
@@ -320,6 +336,10 @@ void gtk_css_other_values_compute_changes_and_affects (GtkCssStyle *style1,
                                                       GtkCssStyle *style2,
                                                       GtkBitmask    **changes,
                                                       GtkCssAffects *affects);
+void gtk_css_custom_values_compute_changes_and_affects (GtkCssStyle *style1,
+                                                      GtkCssStyle *style2,
+                                                      GtkBitmask    **changes,
+                                                      GtkCssAffects *affects);
 
 G_END_DECLS
 

gtk/gtkcsstransformvalue.c

@@ -273,12 +273,13 @@ gtk_css_value_transform_free (GtkCssValue *value)
 
 /* returns TRUE if dest == src */
 static gboolean
-gtk_css_transform_compute (GtkCssTransform  *dest,
-                           GtkCssTransform  *src,
-                           guint             property_id,
-                           GtkStyleProvider *provider,
-                           GtkCssStyle      *style,
-                           GtkCssStyle      *parent_style)
+gtk_css_transform_compute (GtkCssTransform   *dest,
+                           GtkCssTransform   *src,
+                           guint              property_id,
+                           GtkStyleProvider  *provider,
+                           GtkCssStyle       *style,
+                           GtkCssStyle       *parent_style,
+                           GtkCssVariableSet *variables)
 {
   dest->type = src->type;
 
@@ -288,41 +289,41 @@ gtk_css_transform_compute (GtkCssTransform  *dest,
       memcpy (dest, src, sizeof (GtkCssTransform));
       return TRUE;
     case GTK_CSS_TRANSFORM_TRANSLATE:
-      dest->translate.x = _gtk_css_value_compute (src->translate.x, property_id, provider, style, parent_style);
-      dest->translate.y = _gtk_css_value_compute (src->translate.y, property_id, provider, style, parent_style);
-      dest->translate.z = _gtk_css_value_compute (src->translate.z, property_id, provider, style, parent_style);
+      dest->translate.x = _gtk_css_value_compute (src->translate.x, property_id, provider, style, parent_style, variables);
+      dest->translate.y = _gtk_css_value_compute (src->translate.y, property_id, provider, style, parent_style, variables);
+      dest->translate.z = _gtk_css_value_compute (src->translate.z, property_id, provider, style, parent_style, variables);
       return dest->translate.x == src->translate.x
           && dest->translate.y == src->translate.y
           && dest->translate.z == src->translate.z;
     case GTK_CSS_TRANSFORM_ROTATE:
-      dest->rotate.x = _gtk_css_value_compute (src->rotate.x, property_id, provider, style, parent_style);
-      dest->rotate.y = _gtk_css_value_compute (src->rotate.y, property_id, provider, style, parent_style);
-      dest->rotate.z = _gtk_css_value_compute (src->rotate.z, property_id, provider, style, parent_style);
-      dest->rotate.angle = _gtk_css_value_compute (src->rotate.angle, property_id, provider, style, parent_style);
+      dest->rotate.x = _gtk_css_value_compute (src->rotate.x, property_id, provider, style, parent_style, variables);
+      dest->rotate.y = _gtk_css_value_compute (src->rotate.y, property_id, provider, style, parent_style, variables);
+      dest->rotate.z = _gtk_css_value_compute (src->rotate.z, property_id, provider, style, parent_style, variables);
+      dest->rotate.angle = _gtk_css_value_compute (src->rotate.angle, property_id, provider, style, parent_style, variables);
       return dest->rotate.x == src->rotate.x
           && dest->rotate.y == src->rotate.y
           && dest->rotate.z == src->rotate.z
           && dest->rotate.angle == src->rotate.angle;
     case GTK_CSS_TRANSFORM_SCALE:
-      dest->scale.x = _gtk_css_value_compute (src->scale.x, property_id, provider, style, parent_style);
-      dest->scale.y = _gtk_css_value_compute (src->scale.y, property_id, provider, style, parent_style);
-      dest->scale.z = _gtk_css_value_compute (src->scale.z, property_id, provider, style, parent_style);
+      dest->scale.x = _gtk_css_value_compute (src->scale.x, property_id, provider, style, parent_style, variables);
+      dest->scale.y = _gtk_css_value_compute (src->scale.y, property_id, provider, style, parent_style, variables);
+      dest->scale.z = _gtk_css_value_compute (src->scale.z, property_id, provider, style, parent_style, variables);
       return dest->scale.x == src->scale.x
           && dest->scale.y == src->scale.y
           && dest->scale.z == src->scale.z;
     case GTK_CSS_TRANSFORM_SKEW:
-      dest->skew.x = _gtk_css_value_compute (src->skew.x, property_id, provider, style, parent_style);
-      dest->skew.y = _gtk_css_value_compute (src->skew.y, property_id, provider, style, parent_style);
+      dest->skew.x = _gtk_css_value_compute (src->skew.x, property_id, provider, style, parent_style, variables);
+      dest->skew.y = _gtk_css_value_compute (src->skew.y, property_id, provider, style, parent_style, variables);
       return dest->skew.x == src->skew.x
           && dest->skew.y == src->skew.y;
     case GTK_CSS_TRANSFORM_SKEW_X:
-      dest->skew_x.skew = _gtk_css_value_compute (src->skew_x.skew, property_id, provider, style, parent_style);
+      dest->skew_x.skew = _gtk_css_value_compute (src->skew_x.skew, property_id, provider, style, parent_style, variables);
       return dest->skew_x.skew == src->skew_x.skew;
     case GTK_CSS_TRANSFORM_SKEW_Y:
-      dest->skew_y.skew = _gtk_css_value_compute (src->skew_y.skew, property_id, provider, style, parent_style);
+      dest->skew_y.skew = _gtk_css_value_compute (src->skew_y.skew, property_id, provider, style, parent_style, variables);
       return dest->skew_y.skew == src->skew_y.skew;
     case GTK_CSS_TRANSFORM_PERSPECTIVE:
-      dest->perspective.depth = _gtk_css_value_compute (src->perspective.depth, property_id, provider, style, parent_style);
+      dest->perspective.depth = _gtk_css_value_compute (src->perspective.depth, property_id, provider, style, parent_style, variables);
       return dest->perspective.depth == src->perspective.depth;
     case GTK_CSS_TRANSFORM_NONE:
     default:
@@ -332,11 +333,12 @@ gtk_css_transform_compute (GtkCssTransform  *dest,
 }
 
 static GtkCssValue *
-gtk_css_value_transform_compute (GtkCssValue      *value,
-                                 guint             property_id,
-                                 GtkStyleProvider *provider,
-                                 GtkCssStyle      *style,
-                                 GtkCssStyle      *parent_style)
+gtk_css_value_transform_compute (GtkCssValue       *value,
+                                 guint              property_id,
+                                 GtkStyleProvider  *provider,
+                                 GtkCssStyle       *style,
+                                 GtkCssStyle       *parent_style,
+                                 GtkCssVariableSet *variables)
 {
   GtkCssValue *result;
   gboolean changes;
@@ -356,7 +358,8 @@ gtk_css_value_transform_compute (GtkCssValue      *value,
                                              property_id,
                                              provider,
                                              style,
-                                             parent_style);
+                                             parent_style,
+                                             variables);
     }
 
   if (!changes)
@@ -801,7 +804,7 @@ static const GtkCssValueClass GTK_CSS_VALUE_TRANSFORM = {
   gtk_css_value_transform_print
 };
 
-static GtkCssValue transform_none_singleton = { &GTK_CSS_VALUE_TRANSFORM, 1, TRUE, 0, {  { GTK_CSS_TRANSFORM_NONE } } };
+static GtkCssValue transform_none_singleton = { &GTK_CSS_VALUE_TRANSFORM, 1, TRUE, FALSE, 0, {  { GTK_CSS_TRANSFORM_NONE } } };
 
 static GtkCssValue *
 gtk_css_transform_value_alloc (guint n_transforms)

gtk/gtkcsstypesprivate.h

@@ -277,7 +277,8 @@ enum { /*< skip >*/
   GTK_CSS_PROPERTY_FONT_VARIATION_SETTINGS,
   GTK_CSS_PROPERTY_LINE_HEIGHT,
   /* add more */
-  GTK_CSS_PROPERTY_N_PROPERTIES
+  GTK_CSS_PROPERTY_N_PROPERTIES,
+  GTK_CSS_PROPERTY_CUSTOM,
 };
 
 typedef enum /*< skip >*/ {

gtk/gtkcssunsetvalue.c

@@ -35,11 +35,12 @@ gtk_css_value_unset_free (GtkCssValue *value)
 }
 
 static GtkCssValue *
-gtk_css_value_unset_compute (GtkCssValue      *value,
-                             guint             property_id,
-                             GtkStyleProvider *provider,
-                             GtkCssStyle      *style,
-                             GtkCssStyle      *parent_style)
+gtk_css_value_unset_compute (GtkCssValue       *value,
+                             guint              property_id,
+                             GtkStyleProvider  *provider,
+                             GtkCssStyle       *style,
+                             GtkCssStyle       *parent_style,
+                             GtkCssVariableSet *variables)
 {
   GtkCssStyleProperty *property;
   GtkCssValue *unset_value;
@@ -55,7 +56,8 @@ gtk_css_value_unset_compute (GtkCssValue      *value,
                                  property_id,
                                  provider,
                                  style,
-                                 parent_style);
+                                 parent_style,
+                                 variables);
 }
 
 static gboolean

gtk/gtkcssvalue.c

@@ -199,6 +199,7 @@ gtk_css_value_unref (GtkCssValue *value)
  * @provider: Style provider for looking up extra information
  * @style: Style to compute for
  * @parent_style: parent style to use for inherited values
+ * @variables: an additional set of variables to use along with @style
  *
  * Converts the specified @value into the computed value for the CSS
  * property given by @property_id using the information in @context.
@@ -208,11 +209,12 @@ gtk_css_value_unref (GtkCssValue *value)
  * Returns: the computed value
  **/
 GtkCssValue *
-_gtk_css_value_compute (GtkCssValue      *value,
-                        guint             property_id,
-                        GtkStyleProvider *provider,
-                        GtkCssStyle      *style,
-                        GtkCssStyle      *parent_style)
+_gtk_css_value_compute (GtkCssValue       *value,
+                        guint              property_id,
+                        GtkStyleProvider  *provider,
+                        GtkCssStyle       *style,
+                        GtkCssStyle       *parent_style,
+                        GtkCssVariableSet *variables)
 {
   if (gtk_css_value_is_computed (value))
     return _gtk_css_value_ref (value);
@@ -221,7 +223,7 @@ _gtk_css_value_compute (GtkCssValue      *value,
   get_accounting_data (value->class->type_name)->computed++;
 #endif
 
-  return value->class->compute (value, property_id, provider, style, parent_style);
+  return value->class->compute (value, property_id, provider, style, parent_style, variables);
 }
 
 gboolean
@@ -367,3 +369,9 @@ gtk_css_value_is_computed (const GtkCssValue *value)
 {
   return value->is_computed;
 }
+
+gboolean
+gtk_css_value_contains_variables (const GtkCssValue *value)
+{
+  return value->contains_variables;
+}

gtk/gtkcssvalueprivate.h

@@ -22,6 +22,7 @@
 #include <glib-object.h>
 
 #include "gtkcsstypesprivate.h"
+#include "gtkcssvariablesetprivate.h"
 #include "gtkstyleprovider.h"
 
 G_BEGIN_DECLS
@@ -37,7 +38,8 @@ typedef struct _GtkCssValueClass      GtkCssValueClass;
 #define GTK_CSS_VALUE_BASE \
   const GtkCssValueClass *class; \
   int ref_count; \
-  guint is_computed: 1;
+  guint is_computed: 1; \
+  guint contains_variables: 1;
 
 struct _GtkCssValueClass {
   const char *type_name;
@@ -47,7 +49,8 @@ struct _GtkCssValueClass {
                                                        guint                       property_id,
                                                        GtkStyleProvider           *provider,
                                                        GtkCssStyle                *style,
-                                                       GtkCssStyle                *parent_style);
+                                                       GtkCssStyle                *parent_style,
+                                                       GtkCssVariableSet          *variables);
   gboolean      (* equal)                             (const GtkCssValue          *value1,
                                                        const GtkCssValue          *value2);
   GtkCssValue * (* transition)                        (GtkCssValue                *start,
@@ -76,7 +79,8 @@ GtkCssValue *_gtk_css_value_compute                   (GtkCssValue
                                                        guint                       property_id,
                                                        GtkStyleProvider           *provider,
                                                        GtkCssStyle                *style,
-                                                       GtkCssStyle                *parent_style) G_GNUC_PURE;
+                                                       GtkCssStyle                *parent_style,
+                                                       GtkCssVariableSet          *variables) G_GNUC_PURE;
 gboolean     _gtk_css_value_equal                     (const GtkCssValue          *value1,
                                                        const GtkCssValue          *value2) G_GNUC_PURE;
 gboolean     _gtk_css_value_equal0                    (const GtkCssValue          *value1,
@@ -93,6 +97,7 @@ char *       _gtk_css_value_to_string                 (const GtkCssValue
 void         _gtk_css_value_print                     (const GtkCssValue          *value,
                                                        GString                    *string);
 gboolean     gtk_css_value_is_computed                (const GtkCssValue          *value) G_GNUC_PURE;
+gboolean     gtk_css_value_contains_variables         (const GtkCssValue          *value) G_GNUC_PURE;
 
 G_END_DECLS
 

gtk/gtkcssvaluesprivate.h

@@ -0,0 +1,151 @@
+/*
+ * Copyright © 2012 Red Hat Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#pragma once
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+static const int core_props[] = {
+  GTK_CSS_PROPERTY_COLOR,
+  GTK_CSS_PROPERTY_DPI,
+  GTK_CSS_PROPERTY_FONT_SIZE,
+  GTK_CSS_PROPERTY_ICON_PALETTE
+};
+
+static const int background_props[] = {
+  GTK_CSS_PROPERTY_BACKGROUND_COLOR,
+  GTK_CSS_PROPERTY_BOX_SHADOW,
+  GTK_CSS_PROPERTY_BACKGROUND_CLIP,
+  GTK_CSS_PROPERTY_BACKGROUND_ORIGIN,
+  GTK_CSS_PROPERTY_BACKGROUND_SIZE,
+  GTK_CSS_PROPERTY_BACKGROUND_POSITION,
+  GTK_CSS_PROPERTY_BACKGROUND_REPEAT,
+  GTK_CSS_PROPERTY_BACKGROUND_IMAGE,
+  GTK_CSS_PROPERTY_BACKGROUND_BLEND_MODE
+};
+
+static const int border_props[] = {
+  GTK_CSS_PROPERTY_BORDER_TOP_STYLE,
+  GTK_CSS_PROPERTY_BORDER_TOP_WIDTH,
+  GTK_CSS_PROPERTY_BORDER_LEFT_STYLE,
+  GTK_CSS_PROPERTY_BORDER_LEFT_WIDTH,
+  GTK_CSS_PROPERTY_BORDER_BOTTOM_STYLE,
+  GTK_CSS_PROPERTY_BORDER_BOTTOM_WIDTH,
+  GTK_CSS_PROPERTY_BORDER_RIGHT_STYLE,
+  GTK_CSS_PROPERTY_BORDER_RIGHT_WIDTH,
+  GTK_CSS_PROPERTY_BORDER_TOP_LEFT_RADIUS,
+  GTK_CSS_PROPERTY_BORDER_TOP_RIGHT_RADIUS,
+  GTK_CSS_PROPERTY_BORDER_BOTTOM_RIGHT_RADIUS,
+  GTK_CSS_PROPERTY_BORDER_BOTTOM_LEFT_RADIUS,
+  GTK_CSS_PROPERTY_BORDER_TOP_COLOR,
+  GTK_CSS_PROPERTY_BORDER_RIGHT_COLOR,
+  GTK_CSS_PROPERTY_BORDER_BOTTOM_COLOR,
+  GTK_CSS_PROPERTY_BORDER_LEFT_COLOR,
+  GTK_CSS_PROPERTY_BORDER_IMAGE_SOURCE,
+  GTK_CSS_PROPERTY_BORDER_IMAGE_REPEAT,
+  GTK_CSS_PROPERTY_BORDER_IMAGE_SLICE,
+  GTK_CSS_PROPERTY_BORDER_IMAGE_WIDTH
+};
+
+static const int icon_props[] = {
+  GTK_CSS_PROPERTY_ICON_SIZE,
+  GTK_CSS_PROPERTY_ICON_SHADOW,
+  GTK_CSS_PROPERTY_ICON_STYLE,
+};
+
+static const int outline_props[] = {
+  GTK_CSS_PROPERTY_OUTLINE_STYLE,
+  GTK_CSS_PROPERTY_OUTLINE_WIDTH,
+  GTK_CSS_PROPERTY_OUTLINE_OFFSET,
+  GTK_CSS_PROPERTY_OUTLINE_COLOR,
+};
+
+static const int font_props[] = {
+  GTK_CSS_PROPERTY_FONT_FAMILY,
+  GTK_CSS_PROPERTY_FONT_STYLE,
+  GTK_CSS_PROPERTY_FONT_WEIGHT,
+  GTK_CSS_PROPERTY_FONT_STRETCH,
+  GTK_CSS_PROPERTY_LETTER_SPACING,
+  GTK_CSS_PROPERTY_TEXT_SHADOW,
+  GTK_CSS_PROPERTY_CARET_COLOR,
+  GTK_CSS_PROPERTY_SECONDARY_CARET_COLOR,
+  GTK_CSS_PROPERTY_FONT_FEATURE_SETTINGS,
+  GTK_CSS_PROPERTY_FONT_VARIATION_SETTINGS,
+  GTK_CSS_PROPERTY_LINE_HEIGHT,
+};
+
+static const int font_variant_props[] = {
+  GTK_CSS_PROPERTY_TEXT_DECORATION_LINE,
+  GTK_CSS_PROPERTY_TEXT_DECORATION_COLOR,
+  GTK_CSS_PROPERTY_TEXT_DECORATION_STYLE,
+  GTK_CSS_PROPERTY_TEXT_TRANSFORM,
+  GTK_CSS_PROPERTY_FONT_KERNING,
+  GTK_CSS_PROPERTY_FONT_VARIANT_LIGATURES,
+  GTK_CSS_PROPERTY_FONT_VARIANT_POSITION,
+  GTK_CSS_PROPERTY_FONT_VARIANT_CAPS,
+  GTK_CSS_PROPERTY_FONT_VARIANT_NUMERIC,
+  GTK_CSS_PROPERTY_FONT_VARIANT_ALTERNATES,
+  GTK_CSS_PROPERTY_FONT_VARIANT_EAST_ASIAN,
+};
+
+static const int animation_props[] = {
+  GTK_CSS_PROPERTY_ANIMATION_NAME,
+  GTK_CSS_PROPERTY_ANIMATION_DURATION,
+  GTK_CSS_PROPERTY_ANIMATION_TIMING_FUNCTION,
+  GTK_CSS_PROPERTY_ANIMATION_ITERATION_COUNT,
+  GTK_CSS_PROPERTY_ANIMATION_DIRECTION,
+  GTK_CSS_PROPERTY_ANIMATION_PLAY_STATE,
+  GTK_CSS_PROPERTY_ANIMATION_DELAY,
+  GTK_CSS_PROPERTY_ANIMATION_FILL_MODE,
+};
+
+static const int transition_props[] = {
+  GTK_CSS_PROPERTY_TRANSITION_PROPERTY,
+  GTK_CSS_PROPERTY_TRANSITION_DURATION,
+  GTK_CSS_PROPERTY_TRANSITION_TIMING_FUNCTION,
+  GTK_CSS_PROPERTY_TRANSITION_DELAY,
+};
+
+static const int size_props[] = {
+  GTK_CSS_PROPERTY_MARGIN_TOP,
+  GTK_CSS_PROPERTY_MARGIN_LEFT,
+  GTK_CSS_PROPERTY_MARGIN_BOTTOM,
+  GTK_CSS_PROPERTY_MARGIN_RIGHT,
+  GTK_CSS_PROPERTY_PADDING_TOP,
+  GTK_CSS_PROPERTY_PADDING_LEFT,
+  GTK_CSS_PROPERTY_PADDING_BOTTOM,
+  GTK_CSS_PROPERTY_PADDING_RIGHT,
+  GTK_CSS_PROPERTY_BORDER_SPACING,
+  GTK_CSS_PROPERTY_MIN_WIDTH,
+  GTK_CSS_PROPERTY_MIN_HEIGHT,
+};
+
+static const int other_props[] = {
+  GTK_CSS_PROPERTY_ICON_SOURCE,
+  GTK_CSS_PROPERTY_ICON_TRANSFORM,
+  GTK_CSS_PROPERTY_ICON_FILTER,
+  GTK_CSS_PROPERTY_TRANSFORM,
+  GTK_CSS_PROPERTY_TRANSFORM_ORIGIN,
+  GTK_CSS_PROPERTY_OPACITY,
+  GTK_CSS_PROPERTY_FILTER,
+};
+
+G_END_DECLS

gtk/gtkcssvariableset.c

@@ -0,0 +1,359 @@
+/*
+ * Copyright (C) 2023 GNOME Foundation Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alice Mikhaylenko <alicem@gnome.org>
+ */
+
+#include "gtkcssvariablesetprivate.h"
+
+#include "gtkcsscustompropertypoolprivate.h"
+
+static void
+unref_custom_property_name (gpointer pointer)
+{
+  GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
+
+  gtk_css_custom_property_pool_unref (pool, GPOINTER_TO_INT (pointer));
+}
+
+static void
+maybe_unref_variable (gpointer pointer)
+{
+  if (pointer != NULL)
+    gtk_css_variable_value_unref (pointer);
+}
+
+GtkCssVariableSet *
+gtk_css_variable_set_new (void)
+{
+  GtkCssVariableSet *self = g_new0 (GtkCssVariableSet, 1);
+
+  self->ref_count = 1;
+  self->variables = g_hash_table_new_full (g_direct_hash,
+                                           g_direct_equal,
+                                           unref_custom_property_name,
+                                           maybe_unref_variable);
+
+  return self;
+}
+
+GtkCssVariableSet *
+gtk_css_variable_set_ref (GtkCssVariableSet *self)
+{
+  self->ref_count++;
+
+  return self;
+}
+
+void
+gtk_css_variable_set_unref (GtkCssVariableSet *self)
+{
+  self->ref_count--;
+  if (self->ref_count > 0)
+    return;
+
+  g_hash_table_unref (self->variables);
+  g_clear_pointer (&self->parent, gtk_css_variable_set_unref);
+  g_free (self);
+}
+
+GtkCssVariableSet *
+gtk_css_variable_set_copy (GtkCssVariableSet *self)
+{
+  GtkCssVariableSet *ret = gtk_css_variable_set_new ();
+  GHashTableIter iter;
+  gpointer id;
+  GtkCssVariableValue *value;
+
+  g_hash_table_iter_init (&iter, self->variables);
+
+  while (g_hash_table_iter_next (&iter, &id, (gpointer) &value))
+    gtk_css_variable_set_add (ret, GPOINTER_TO_INT (id), value);
+
+  gtk_css_variable_set_set_parent (ret, self->parent);
+
+  return ret;
+}
+
+void
+gtk_css_variable_set_set_parent (GtkCssVariableSet *self,
+                                 GtkCssVariableSet *parent)
+{
+  if (self->parent)
+    gtk_css_variable_set_unref (self->parent);
+
+  self->parent = parent;
+
+  if (self->parent)
+    gtk_css_variable_set_ref (self->parent);
+}
+
+void
+gtk_css_variable_set_add (GtkCssVariableSet   *self,
+                          int                  id,
+                          GtkCssVariableValue *value)
+{
+  GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
+
+  g_hash_table_insert (self->variables,
+                       GINT_TO_POINTER (gtk_css_custom_property_pool_ref (pool, id)),
+                       value ? gtk_css_variable_value_ref (value) : NULL);
+}
+
+static gboolean check_variable (GtkCssVariableSet   *self,
+                                GHashTable          *unvisited_variables,
+                                GArray              *stack,
+                                int                  id,
+                                GtkCssVariableValue *value);
+
+static gboolean
+check_references (GtkCssVariableSet   *self,
+                  GHashTable          *unvisited_variables,
+                  GArray              *stack,
+                  GtkCssVariableValue *value)
+{
+  GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
+  int i;
+
+  for (i = 0; i < value->n_references; i++)
+    {
+      GtkCssVariableValueReference *ref = &value->references[i];
+      int ref_id = gtk_css_custom_property_pool_lookup (pool, ref->name);
+
+      if (g_hash_table_contains (unvisited_variables, GINT_TO_POINTER (ref_id)))
+        {
+          GtkCssVariableValue *ref_value;
+
+          ref_value = g_hash_table_lookup (self->variables, GINT_TO_POINTER (ref_id));
+
+          if (check_variable (self, unvisited_variables, stack, ref_id, ref_value))
+            return TRUE;
+        }
+
+      if (ref->fallback)
+        {
+          if (check_references (self, unvisited_variables, stack, ref->fallback))
+            return TRUE;
+        }
+    }
+
+    return FALSE;
+}
+
+static gboolean
+check_variable (GtkCssVariableSet   *self,
+                GHashTable          *unvisited_variables,
+                GArray              *stack,
+                int                  id,
+                GtkCssVariableValue *value)
+{
+  int i;
+
+  g_array_append_val (stack, id);
+
+  for (i = stack->len - 2; i >= 0; i--)
+    {
+      /* Found a cycle, stop checking */
+      if (id == g_array_index (stack, int, i))
+        return TRUE;
+    }
+
+  if (check_references (self, unvisited_variables, stack, value))
+    return TRUE;
+
+  g_array_remove_index_fast (stack, stack->len - 1);
+  g_hash_table_remove (unvisited_variables, GINT_TO_POINTER (id));
+
+  return FALSE;
+}
+
+void
+gtk_css_variable_set_resolve_cycles (GtkCssVariableSet *self)
+{
+  GHashTable *variables = g_hash_table_new (g_direct_hash, g_direct_equal);
+  GHashTable *unvisited_variables = g_hash_table_new (g_direct_hash, g_direct_equal);
+  GArray *stack;
+  GHashTableIter iter;
+  gpointer id;
+  GtkCssVariableValue *value;
+
+  stack = g_array_new (FALSE, FALSE, sizeof (int));
+
+  g_hash_table_iter_init (&iter, self->variables);
+
+  while (g_hash_table_iter_next (&iter, &id, (gpointer) &value))
+    {
+      /* Have 2 copies of self->variables: "variables" can be iterated safely as
+       * we remove values, and "unvisited_variables" as a visited node marker
+       * for DFS */
+      g_hash_table_insert (variables, id, value);
+      g_hash_table_add (unvisited_variables, id);
+    }
+
+  g_hash_table_iter_init (&iter, variables);
+
+  while (g_hash_table_iter_next (&iter, &id, (gpointer) &value))
+    {
+      if (!g_hash_table_contains (unvisited_variables, id))
+        continue;
+
+      if (!g_hash_table_contains (self->variables, id))
+        continue;
+
+      if (check_variable (self, unvisited_variables, stack, GPOINTER_TO_INT (id), value))
+        {
+          int i;
+
+          /* Found a cycle, remove the offending variables */
+          for (i = stack->len - 2; i >= 0; i--)
+            {
+              int id_to_remove = g_array_index (stack, int, i);
+
+              g_hash_table_remove (self->variables, GINT_TO_POINTER (id_to_remove));
+
+              if (g_array_index (stack, int, i) == g_array_index (stack, int, stack->len - 1))
+                break;
+            }
+
+          g_array_remove_range (stack, 0, stack->len);
+        }
+    }
+
+  g_array_unref (stack);
+  g_hash_table_unref (variables);
+  g_hash_table_unref (unvisited_variables);
+}
+
+GtkCssVariableValue *
+gtk_css_variable_set_lookup (GtkCssVariableSet  *self,
+                             int                 id,
+                             GtkCssVariableSet **source)
+{
+  GtkCssVariableValue *ret = g_hash_table_lookup (self->variables, GINT_TO_POINTER (id));
+
+  if (ret)
+    {
+      if (source)
+        *source = self;
+      return ret;
+    }
+
+  if (self->parent)
+    return gtk_css_variable_set_lookup (self->parent, id, source);
+
+  if (source)
+    *source = NULL;
+
+  return NULL;
+}
+
+static void
+list_ids_recursive (GtkCssVariableSet *self,
+                    GHashTable        *table)
+{
+  GHashTableIter iter;
+  gpointer id;
+
+  if (self->parent)
+    list_ids_recursive (self->parent, table);
+
+  g_hash_table_iter_init (&iter, self->variables);
+
+  while (g_hash_table_iter_next (&iter, &id, NULL))
+    g_hash_table_add (table, id);
+}
+
+static int
+compare_ids (gconstpointer a, gconstpointer b, gpointer user_data)
+{
+  GtkCssCustomPropertyPool *pool = user_data;
+  int id1 = GPOINTER_TO_INT (*((const int *) a));
+  int id2 = GPOINTER_TO_INT (*((const int *) b));
+  const char *name1, *name2;
+
+  name1 = gtk_css_custom_property_pool_get_name (pool, id1);
+  name2 = gtk_css_custom_property_pool_get_name (pool, id2);
+
+  return strcmp (name1, name2);
+}
+
+GArray *
+gtk_css_variable_set_list_ids (GtkCssVariableSet  *self)
+{
+  GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
+  GArray *ret = g_array_new (FALSE, FALSE, sizeof (int));
+  GHashTable *all_ids;
+  GHashTableIter iter;
+  gpointer id;
+
+  all_ids = g_hash_table_new (g_direct_hash, g_direct_equal);
+  list_ids_recursive (self, all_ids);
+
+  g_hash_table_iter_init (&iter, all_ids);
+
+  while (g_hash_table_iter_next (&iter, &id, NULL))
+    g_array_append_val (ret, id);
+
+  g_hash_table_unref (all_ids);
+
+  g_array_sort_with_data (ret, compare_ids, pool);
+
+  return ret;
+}
+
+gboolean
+gtk_css_variable_set_equal (GtkCssVariableSet *set1,
+                            GtkCssVariableSet *set2)
+{
+  GHashTableIter iter;
+  gpointer id;
+  GtkCssVariableValue *value1;
+
+  if (set1 == set2)
+    return TRUE;
+
+  if (set1 == NULL || set2 == NULL)
+    return FALSE;
+
+  if (g_hash_table_size (set1->variables) != g_hash_table_size (set2->variables))
+    return FALSE;
+
+  if (set1->parent != set2->parent)
+    return FALSE;
+
+  g_hash_table_iter_init (&iter, set2->variables);
+
+  while (g_hash_table_iter_next (&iter, &id, NULL))
+    {
+      if (!g_hash_table_contains (set1->variables, id))
+        return FALSE;
+    }
+
+  g_hash_table_iter_init (&iter, set1->variables);
+
+  while (g_hash_table_iter_next (&iter, &id, (gpointer) &value1))
+    {
+      GtkCssVariableValue *value2 = g_hash_table_lookup (set2->variables, id);
+
+      if (value2 == NULL)
+         return FALSE;
+
+      if (!gtk_css_variable_value_equal (value1, value2))
+         return FALSE;
+    }
+
+  return TRUE;
+}

gtk/gtkcssvariablesetprivate.h

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2023 GNOME Foundation Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Alice Mikhaylenko <alicem@gnome.org>
+ */
+
+#pragma once
+
+#include "gtk/css/gtkcssvariablevalueprivate.h"
+
+G_BEGIN_DECLS
+
+typedef struct _GtkCssVariableSet GtkCssVariableSet;
+
+struct _GtkCssVariableSet
+{
+  int ref_count;
+
+  GHashTable *variables;
+  GtkCssVariableSet *parent;
+};
+
+GtkCssVariableSet *  gtk_css_variable_set_new            (void);
+
+GtkCssVariableSet *  gtk_css_variable_set_ref            (GtkCssVariableSet   *self);
+void                 gtk_css_variable_set_unref          (GtkCssVariableSet   *self);
+
+GtkCssVariableSet *  gtk_css_variable_set_copy           (GtkCssVariableSet   *self);
+
+void                 gtk_css_variable_set_set_parent     (GtkCssVariableSet   *self,
+                                                          GtkCssVariableSet   *parent);
+
+void                 gtk_css_variable_set_add            (GtkCssVariableSet   *self,
+                                                          int                  id,
+                                                          GtkCssVariableValue *value);
+void                 gtk_css_variable_set_resolve_cycles (GtkCssVariableSet   *self);
+
+GtkCssVariableValue *gtk_css_variable_set_lookup         (GtkCssVariableSet   *self,
+                                                          int                  id,
+                                                          GtkCssVariableSet  **source);
+
+GArray *             gtk_css_variable_set_list_ids       (GtkCssVariableSet   *self);
+
+gboolean             gtk_css_variable_set_equal          (GtkCssVariableSet   *set1,
+                                                          GtkCssVariableSet   *set2);
+
+G_END_DECLS

gtk/gtkstylecascade.c

@@ -208,6 +208,29 @@ gtk_style_cascade_lookup (GtkStyleProvider             *provider,
   gtk_style_cascade_iter_clear (&iter);
 }
 
+static void
+gtk_style_cascade_emit_error (GtkStyleProvider *provider,
+                              GtkCssSection    *section,
+                              const GError     *error)
+{
+  GtkStyleCascade *cascade = GTK_STYLE_CASCADE (provider);
+  GtkStyleCascadeIter iter;
+  GtkStyleProvider *item;
+
+  for (item = gtk_style_cascade_iter_init (cascade, &iter);
+       item;
+       item = gtk_style_cascade_iter_next (cascade, &iter))
+    {
+      if (gtk_style_provider_has_section (item, section))
+        {
+          gtk_style_provider_emit_error (item, section, (GError *) error);
+          break;
+        }
+    }
+
+  gtk_style_cascade_iter_clear (&iter);
+}
+
 static void
 gtk_style_cascade_provider_iface_init (GtkStyleProviderInterface *iface)
 {
@@ -216,6 +239,7 @@ gtk_style_cascade_provider_iface_init (GtkStyleProviderInterface *iface)
   iface->get_scale = gtk_style_cascade_get_scale;
   iface->get_keyframes = gtk_style_cascade_get_keyframes;
   iface->lookup = gtk_style_cascade_lookup;
+  iface->emit_error = gtk_style_cascade_emit_error;
 }
 
 G_DEFINE_TYPE_EXTENDED (GtkStyleCascade, _gtk_style_cascade, G_TYPE_OBJECT, 0,

gtk/gtkstyleprovider.c

@@ -170,6 +170,19 @@ gtk_style_provider_emit_error (GtkStyleProvider *provider,
     iface->emit_error (provider, section, error);
 }
 
+gboolean
+gtk_style_provider_has_section (GtkStyleProvider *provider,
+                                GtkCssSection    *section)
+{
+  GtkStyleProviderInterface *iface;
+
+  iface = GTK_STYLE_PROVIDER_GET_INTERFACE (provider);
+
+  if (iface->has_section)
+    return iface->has_section (provider, section);
+
+  return FALSE;
+}
 
 /* These apis are misnamed, and the rest of GtkStyleContext is deprecated,
  * so put them here for now
@@ -230,4 +243,3 @@ gtk_style_context_remove_provider_for_display (GdkDisplay       *display,
   cascade = _gtk_settings_get_style_cascade (gtk_settings_get_for_display (display), 1);
   _gtk_style_cascade_remove_provider (cascade, provider);
 }
-

gtk/gtkstyleproviderprivate.h

@@ -52,6 +52,8 @@ struct _GtkStyleProviderInterface
                                                  const GError            *error);
   /* signal */
   void                  (* changed)             (GtkStyleProvider        *provider);
+  gboolean              (* has_section)         (GtkStyleProvider        *provider,
+                                                 GtkCssSection           *section);
 };
 
 GtkSettings *           gtk_style_provider_get_settings          (GtkStyleProvider        *provider);
@@ -71,6 +73,8 @@ void                    gtk_style_provider_changed               (GtkStyleProvid
 void                    gtk_style_provider_emit_error            (GtkStyleProvider        *provider,
                                                                   GtkCssSection           *section,
                                                                   GError                  *error);
+gboolean                gtk_style_provider_has_section           (GtkStyleProvider        *provider,
+                                                                  GtkCssSection           *section);
 
 G_END_DECLS
 

gtk/inspector/css-node-tree.c

@@ -28,6 +28,7 @@
 
 #include "gtklabel.h"
 #include "gtk/gtkwidgetprivate.h"
+#include "gtkcsscustompropertypoolprivate.h"
 #include "gtkcssproviderprivate.h"
 #include "gtkcssstylepropertyprivate.h"
 #include "gtkcssstyleprivate.h"
@@ -600,6 +601,33 @@ bind_node_state (GtkSignalListItemFactory *factory,
   g_free (text);
 }
 
+static int
+compare_name_cb (gconstpointer a,
+                 gconstpointer b,
+                 gpointer      user_data)
+{
+  const CssProperty *prop_a = a;
+  const CssProperty *prop_b = b;
+  gboolean a_var = prop_a->name[0] == '-' && prop_a->name[1] == '-';
+  gboolean b_var = prop_b->name[0] == '-' && prop_b->name[1] == '-';
+  gboolean a_gtk = prop_a->name[0] == '-' && prop_a->name[1] != '-';
+  gboolean b_gtk = prop_b->name[0] == '-' && prop_b->name[1] != '-';
+  int ret;
+
+  if (a_var && !b_var)
+    ret = 1;
+  else if (b_var && !a_var)
+    ret = -1;
+  else if (a_gtk && !b_gtk)
+    ret = 1;
+  else if (b_gtk && !a_gtk)
+    ret = -1;
+  else
+    ret = g_utf8_collate (prop_a->name, prop_b->name);
+
+  return gtk_ordering_from_cmpfunc (ret);
+}
+
 static void
 gtk_inspector_css_node_tree_init (GtkInspectorCssNodeTree *cnt)
 {
@@ -676,7 +704,7 @@ gtk_inspector_css_node_tree_init (GtkInspectorCssNodeTree *cnt)
   g_signal_connect (factory, "setup", G_CALLBACK (setup_label), NULL);
   g_signal_connect (factory, "bind", G_CALLBACK (bind_name), NULL);
   gtk_column_view_column_set_factory (column, factory);
-  sorter = GTK_SORTER (gtk_string_sorter_new (gtk_property_expression_new (css_property_get_type (), NULL, "name")));
+  sorter = GTK_SORTER (gtk_custom_sorter_new ((GCompareDataFunc) compare_name_cb, NULL, NULL));
   gtk_column_view_column_set_sorter (column, sorter);
   gtk_column_view_sort_by_column (GTK_COLUMN_VIEW (priv->prop_tree), column, GTK_SORT_ASCENDING);
   g_object_unref (sorter);
@@ -773,9 +801,14 @@ gtk_inspector_css_node_tree_update_style (GtkInspectorCssNodeTree *cnt,
                                           GtkCssStyle             *new_style)
 {
   GtkInspectorCssNodeTreePrivate *priv = cnt->priv;
-  int i;
+  GtkCssCustomPropertyPool *pool = gtk_css_custom_property_pool_get ();
+  GArray *custom_props;
+  int i, n, n_props;
 
-  for (i = 0; i < _gtk_css_style_property_get_n_properties (); i++)
+  n_props = _gtk_css_style_property_get_n_properties ();
+  n = g_list_model_get_n_items (G_LIST_MODEL (priv->prop_model));
+
+  for (i = 0; i < n_props; i++)
     {
       GtkCssStyleProperty *prop;
       const char *name;
@@ -809,6 +842,47 @@ gtk_inspector_css_node_tree_update_style (GtkInspectorCssNodeTree *cnt,
       g_free (location);
       g_free (value);
     }
+
+  g_list_store_splice (priv->prop_model, n_props, n - n_props, NULL, 0);
+
+  if (new_style)
+    {
+      custom_props = gtk_css_style_list_custom_properties (new_style);
+
+      if (custom_props)
+        {
+          for (i = 0; i < custom_props->len; i++)
+            {
+              GtkCssVariableValue *var_value;
+              int id;
+              const char *name;
+              GtkCssSection *section;
+              char *location;
+              char *value;
+              CssProperty *property;
+
+              id = g_array_index (custom_props, int, i);
+              name = gtk_css_custom_property_pool_get_name (pool, id);
+              var_value = gtk_css_style_get_custom_property (new_style, id);
+
+              value = gtk_css_variable_value_to_string (var_value);
+
+              section = var_value->section;
+              if (section)
+                location = gtk_css_section_to_string (section);
+              else
+                location = NULL;
+
+              property = css_property_new (name, value, location);
+              g_list_store_append (priv->prop_model, property);
+
+              g_free (location);
+              g_free (value);
+            }
+
+          g_array_unref (custom_props);
+        }
+    }
 }
 
 static void

gtk/meson.build

@@ -53,6 +53,7 @@ gtk_private_sources = files([
   'gtkcsscalcvalue.c',
   'gtkcsscolorvalue.c',
   'gtkcsscornervalue.c',
+  'gtkcsscustompropertypool.c',
   'gtkcssdimensionvalue.c',
   'gtkcssdynamic.c',
   'gtkcsseasevalue.c',
@@ -84,6 +85,7 @@ gtk_private_sources = files([
   'gtkcssnumbervalue.c',
   'gtkcsspalettevalue.c',
   'gtkcsspositionvalue.c',
+  'gtkcssreferencevalue.c',
   'gtkcssrepeatvalue.c',
   'gtkcssselector.c',
   'gtkcssshadowvalue.c',
@@ -101,6 +103,7 @@ gtk_private_sources = files([
   'gtkcsstypes.c',
   'gtkcssunsetvalue.c',
   'gtkcssvalue.c',
+  'gtkcssvariableset.c',
   'gtkcsswidgetnode.c',
   'gtkdrop.c',
   'gtkfilechooserentry.c',

testsuite/css/change/test5.css

@@ -0,0 +1,14 @@
+/* test variable changes */
+
+box {
+  --test: red;
+  color: var(--test, green);
+}
+
+label:hover {
+  --test: blue;
+}
+
+label:active {
+  --test: initial;
+}

testsuite/css/change/test5.nodes

@@ -0,0 +1,3 @@
+window.background:dir(ltr)    
+  box.horizontal:dir(ltr)    name
+    label.a:dir(ltr)    name|state|hover

testsuite/css/change/test5.ui

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <object class="GtkWindow" id="window1">
+    <property name="can_focus">False</property>
+    <property name="decorated">0</property>
+    <child>
+      <object class="GtkBox">
+        <property name="visible">True</property>
+        <child>
+          <object class="GtkLabel">
+            <style><class name="a"/></style>
+          </object>
+        </child>
+      </object>
+    </child>
+  </object>
+</interface>

testsuite/css/parser/meson.build

@@ -606,6 +606,23 @@ test_data = [
   'value-none.css',
   'value-none.errors',
   'value-none.ref.css',
+  'variables.css',
+  'variables.ref.css',
+  'variables-invalid-01.css',
+  'variables-invalid-01.errors',
+  'variables-invalid-01.ref.css',
+  'variables-invalid-02.css',
+  'variables-invalid-02.errors',
+  'variables-invalid-02.ref.css',
+  'variables-invalid-03.css',
+  'variables-invalid-03.errors',
+  'variables-invalid-03.ref.css',
+  'variables-invalid-04.css',
+  'variables-invalid-04.errors',
+  'variables-invalid-04.ref.css',
+  'variables-invalid-05.css',
+  'variables-invalid-05.errors',
+  'variables-invalid-05.ref.css',
 ]
 
 foreach testname : test_data

testsuite/css/parser/variables-invalid-01.css

@@ -0,0 +1,3 @@
+label {
+  color: var(
+}

testsuite/css/parser/variables-invalid-01.errors

@@ -0,0 +1,5 @@
+variables-invalid-01.css:2:10-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-01.css:2:10-14: error: GTK_CSS_PARSER_ERROR_SYNTAX
+variables-invalid-01.css:2:10-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-01.css:2:3-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-01.css:1:7-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX

testsuite/css/parser/variables-invalid-02.css

@@ -0,0 +1,3 @@
+label {
+  color: var(color);
+}

testsuite/css/parser/variables-invalid-02.errors

@@ -0,0 +1 @@
+variables-invalid-02.css:2:10-14: error: GTK_CSS_PARSER_ERROR_SYNTAX

testsuite/css/parser/variables-invalid-03.css

@@ -0,0 +1,3 @@
+label {
+  color: var(color
+}

testsuite/css/parser/variables-invalid-03.errors

@@ -0,0 +1,5 @@
+variables-invalid-03.css:2:10-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-03.css:2:10-14: error: GTK_CSS_PARSER_ERROR_SYNTAX
+variables-invalid-03.css:2:10-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-03.css:2:3-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-03.css:1:7-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX

testsuite/css/parser/variables-invalid-04.css

@@ -0,0 +1,3 @@
+label {
+  color: var(color,
+}

testsuite/css/parser/variables-invalid-04.errors

@@ -0,0 +1,5 @@
+variables-invalid-04.css:2:10-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-04.css:2:10-14: error: GTK_CSS_PARSER_ERROR_SYNTAX
+variables-invalid-04.css:2:10-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-04.css:2:3-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-04.css:1:7-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX

testsuite/css/parser/variables-invalid-05.css

@@ -0,0 +1,3 @@
+label {
+  color: var(color, var()
+}

testsuite/css/parser/variables-invalid-05.errors

@@ -0,0 +1,5 @@
+variables-invalid-05.css:2:10-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-05.css:2:10-14: error: GTK_CSS_PARSER_ERROR_SYNTAX
+variables-invalid-05.css:2:10-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-05.css:2:3-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX
+variables-invalid-05.css:1:7-4:1: error: GTK_CSS_PARSER_WARNING_SYNTAX

testsuite/css/parser/variables.css

@@ -0,0 +1,14 @@
+:root {
+  --color1: red;
+  --color2: initial;
+}
+
+label {
+  color: var(--color1);
+  background-color: var(--color2, green);
+}
+
+@keyframes aaaa {
+  from { --test: red; --test2: green; }
+  to { --test: blue; --test3: cyan; }
+}

testsuite/css/parser/variables.ref.css

@@ -0,0 +1,20 @@
+@keyframes aaaa {
+  from {
+    --test: red;
+    --test2: green;
+  }
+  to {
+    --test: blue;
+    --test3: cyan;
+  }
+}
+
+label {
+  background-color: var(--color2, green);
+  color: var(--color1);
+}
+
+:root {
+  --color1: red;
+  --color2: initial;
+}

testsuite/css/style/variables.css

@@ -0,0 +1,147 @@
+:root {
+  --color1: red;
+  --not-a-color: 20px;
+
+  /* A dependency cycle */
+  --test1: var(--test2);
+  --test2: var(--test1);
+}
+
+.label-1 {
+  color: var(--color1);
+
+  /* Fallback is unused when the variable resolves */
+  background-color: var(--color1, green);
+
+  /* Nested fallbacks */
+  box-shadow: inset 0 0 3px var(--color2, var(--color3, green));
+}
+
+.label-2 {
+  /* Overriding variables */
+  --color1: yellow;
+  color: var(--color1);
+
+  /* Nonexistent variable, so the fallback is used */
+  background-color: var(--color2, green);
+
+  /* Variables are case-sensitive */
+  box-shadow: inset 0 0 3px var(--Color1, green);
+}
+
+.label-3 {
+  /* Unsetting variables */
+  --color1: initial;
+  color: var(--color1, green);
+
+  /* Shorthand properties */
+  --border1: 3px;
+  --border2: solid red;
+  border: var(--border1, 4px) var(--border2);
+}
+
+.label-4 {
+  /* --test1 is a part of a dependency cycle */
+  /* See https://www.w3.org/TR/css-variables-1/#cycles */
+  color: var(--test1, green);
+
+  /* A dependency cycle with a fallback, the variable is invalid anyway */
+  --test3: var(--test3, green);
+  background-color: var(--test3, purple);
+}
+
+.label-5 {
+  /* Not a dependency cycle since we've overridden --test1. --test2 is still bad */
+  --test1: red;
+  color: var(--test1, green);
+  background-color: var(--test2, green);
+
+  --prop1: lol;
+  --prop2: var(--prop1) var(--prop1);
+  --prop3: var(--prop2) var(--prop2);
+  --prop4: var(--prop3) var(--prop3);
+  --prop5: var(--prop4) var(--prop4);
+  --prop6: var(--prop5) var(--prop5);
+  --prop7: var(--prop6) var(--prop6);
+  --prop8: var(--prop7) var(--prop7);
+  --prop9: var(--prop8) var(--prop8);
+  --prop10: var(--prop9) var(--prop9);
+  --prop11: var(--prop10) var(--prop10);
+  --prop12: var(--prop11) var(--prop11);
+  --prop13: var(--prop12) var(--prop12);
+  --prop14: var(--prop13) var(--prop13);
+  --prop15: var(--prop14) var(--prop14);
+  --prop16: var(--prop15) var(--prop15);
+  --prop17: var(--prop16) var(--prop16);
+  --prop18: var(--prop17) var(--prop17);
+  --prop19: var(--prop18) var(--prop18);
+  --prop20: var(--prop19) var(--prop19);
+
+  /* Fallback is used since --prop20 is too long */
+  /* See https://www.w3.org/TR/css-variables-1/#long-variables */
+  box-shadow: inset 0 0 3px var(--prop20, green);
+}
+
+.label-6 {
+  all: unset;
+
+  /* Should still be red, since variables are not unset by that */
+  color: var(--color1, green);
+}
+
+.label-7 {
+  /* Empty fallback */
+  color: var(--color2,) var(--color1);
+
+  background-color: red;
+}
+
+.label-7 {
+  /* Invalid variable, but this declaration still wins over the one above */
+  background-color: var(--not-a-color);
+}
+
+@keyframes test {
+  from {
+    --test1: red;
+    --test2: blue;
+    --duration: 2s;
+    --padding-right: 10px;
+    padding-left: var(--padding1, 10px);
+    padding-right: var(--padding-right);
+  }
+  to {
+    --test1: blue;
+    --test3: red;
+    --duration: 3s;
+    padding-left: var(--padding2, 20px);
+  }
+}
+
+.label-8 {
+  /* FIXME: this is only there because properties that are only in keyframes */
+  /* won't get printed otherwise */
+  padding-left: 0;
+  padding-right: 0;
+
+  --padding1: 1px;
+  --padding2: 2px;
+
+  /* We're testing the initial state */
+  animation: test 10s infinite linear;
+
+  /* This gets overridden by the animation */
+  --test1: pink;
+
+  color: var(--test1, yellow);
+
+  /* Only defined in the initial state, still fine */
+  background-color: var(--test2, yellow);
+
+  /* Variables only defined later in the animation -> invalid */
+  box-shadow: inset 0 0 3px var(--test3, yellow);
+
+  /* --duration is animation-tainted and so is --duration2, this should be 5s */
+  --duration2: var(--duration, 4s);
+  transition-duration: var(--duration2, 5s);
+}

testsuite/css/style/variables.nodes

@@ -0,0 +1,189 @@
+window.background:dir(ltr)
+  --color1: red; /* variables.css:2:3-17 */
+  --not-a-color: 20px; /* variables.css:3:3-23 */
+
+  box.horizontal:dir(ltr)
+    --color1: red; /* variables.css:2:3-17 */
+    --not-a-color: 20px; /* variables.css:3:3-23 */
+
+    label.label-1:dir(ltr)
+      color: rgb(255,0,0); /* variables.css:11:3-24 */
+      background-color: rgb(255,0,0); /* variables.css:14:3-42 */
+      box-shadow: 0 0 3px rgb(0,128,0) inset; /* variables.css:17:3-65 */
+      --color1: red; /* variables.css:2:3-17 */
+      --not-a-color: 20px; /* variables.css:3:3-23 */
+    label.label-2:dir(ltr)
+      color: rgb(255,255,0); /* variables.css:23:3-24 */
+      background-color: rgb(0,128,0); /* variables.css:26:3-42 */
+      box-shadow: 0 0 3px rgb(0,128,0) inset; /* variables.css:29:3-50 */
+      --color1: yellow; /* variables.css:22:3-20 */
+    label.label-3:dir(ltr)
+      color: rgb(0,128,0); /* variables.css:35:3-31 */
+      border-top-style: solid; /* variables.css:40:3-46 */
+      border-top-width: 3px; /* variables.css:40:3-46 */
+      border-left-style: solid; /* variables.css:40:3-46 */
+      border-left-width: 3px; /* variables.css:40:3-46 */
+      border-bottom-style: solid; /* variables.css:40:3-46 */
+      border-bottom-width: 3px; /* variables.css:40:3-46 */
+      border-right-style: solid; /* variables.css:40:3-46 */
+      border-right-width: 3px; /* variables.css:40:3-46 */
+      border-top-color: rgb(255,0,0); /* variables.css:40:3-46 */
+      border-right-color: rgb(255,0,0); /* variables.css:40:3-46 */
+      border-bottom-color: rgb(255,0,0); /* variables.css:40:3-46 */
+      border-left-color: rgb(255,0,0); /* variables.css:40:3-46 */
+      border-image-source: none; /* variables.css:40:3-46 */
+      border-image-repeat: stretch; /* variables.css:40:3-46 */
+      border-image-slice: 100%; /* variables.css:40:3-46 */
+      border-image-width: 1; /* variables.css:40:3-46 */
+      --border1: 3px; /* variables.css:38:3-18 */
+      --border2: solid red; /* variables.css:39:3-24 */
+      --color1: initial; /* variables.css:34:3-21 */
+    label.label-4:dir(ltr)
+      color: rgb(0,128,0); /* variables.css:46:3-30 */
+      background-color: rgb(128,0,128); /* variables.css:50:3-42 */
+    label.label-5:dir(ltr)
+      color: rgb(255,0,0); /* variables.css:56:3-30 */
+      background-color: rgb(0,128,0); /* variables.css:57:3-41 */
+      box-shadow: 0 0 3px rgb(0,128,0) inset; /* variables.css:82:3-50 */
+      --prop1: lol; /* variables.css:59:3-16 */
+      --prop10: var(--prop9) var(--prop9); /* variables.css:68:3-39 */
+      --prop11: var(--prop10) var(--prop10); /* variables.css:69:3-41 */
+      --prop12: var(--prop11) var(--prop11); /* variables.css:70:3-41 */
+      --prop13: var(--prop12) var(--prop12); /* variables.css:71:3-41 */
+      --prop14: var(--prop13) var(--prop13); /* variables.css:72:3-41 */
+      --prop15: var(--prop14) var(--prop14); /* variables.css:73:3-41 */
+      --prop16: var(--prop15) var(--prop15); /* variables.css:74:3-41 */
+      --prop17: var(--prop16) var(--prop16); /* variables.css:75:3-41 */
+      --prop18: var(--prop17) var(--prop17); /* variables.css:76:3-41 */
+      --prop19: var(--prop18) var(--prop18); /* variables.css:77:3-41 */
+      --prop2: var(--prop1) var(--prop1); /* variables.css:60:3-38 */
+      --prop20: var(--prop19) var(--prop19); /* variables.css:78:3-41 */
+      --prop3: var(--prop2) var(--prop2); /* variables.css:61:3-38 */
+      --prop4: var(--prop3) var(--prop3); /* variables.css:62:3-38 */
+      --prop5: var(--prop4) var(--prop4); /* variables.css:63:3-38 */
+      --prop6: var(--prop5) var(--prop5); /* variables.css:64:3-38 */
+      --prop7: var(--prop6) var(--prop6); /* variables.css:65:3-38 */
+      --prop8: var(--prop7) var(--prop7); /* variables.css:66:3-38 */
+      --prop9: var(--prop8) var(--prop8); /* variables.css:67:3-38 */
+      --test1: red; /* variables.css:55:3-16 */
+    label.label-6:dir(ltr)
+      color: rgb(255,0,0); /* variables.css:89:3-31 */
+      -gtk-dpi: 96; /* variables.css:86:3-14 */
+      font-size: 13.333333333333334px; /* variables.css:86:3-14 */
+      -gtk-icon-palette: error rgb(255,255,255), success rgb(255,255,255), warning rgb(255,255,255); /* variables.css:86:3-14 */
+      background-color: rgba(0,0,0,0); /* variables.css:86:3-14 */
+      font-family: "Sans"; /* variables.css:86:3-14 */
+      font-style: normal; /* variables.css:86:3-14 */
+      font-weight: 400; /* variables.css:86:3-14 */
+      font-stretch: normal; /* variables.css:86:3-14 */
+      letter-spacing: 0; /* variables.css:86:3-14 */
+      text-decoration-line: none; /* variables.css:86:3-14 */
+      text-decoration-color: rgb(255,0,0); /* variables.css:86:3-14 */
+      text-decoration-style: solid; /* variables.css:86:3-14 */
+      text-transform: none; /* variables.css:86:3-14 */
+      font-kerning: auto; /* variables.css:86:3-14 */
+      font-variant-ligatures: normal; /* variables.css:86:3-14 */
+      font-variant-position: normal; /* variables.css:86:3-14 */
+      font-variant-caps: normal; /* variables.css:86:3-14 */
+      font-variant-numeric: normal; /* variables.css:86:3-14 */
+      font-variant-alternates: normal; /* variables.css:86:3-14 */
+      font-variant-east-asian: normal; /* variables.css:86:3-14 */
+      text-shadow: none; /* variables.css:86:3-14 */
+      box-shadow: none; /* variables.css:86:3-14 */
+      margin-top: 0; /* variables.css:86:3-14 */
+      margin-left: 0; /* variables.css:86:3-14 */
+      margin-bottom: 0; /* variables.css:86:3-14 */
+      margin-right: 0; /* variables.css:86:3-14 */
+      padding-top: 0; /* variables.css:86:3-14 */
+      padding-left: 0; /* variables.css:86:3-14 */
+      padding-bottom: 0; /* variables.css:86:3-14 */
+      padding-right: 0; /* variables.css:86:3-14 */
+      border-top-style: none; /* variables.css:86:3-14 */
+      border-top-width: 0; /* variables.css:86:3-14 */
+      border-left-style: none; /* variables.css:86:3-14 */
+      border-left-width: 0; /* variables.css:86:3-14 */
+      border-bottom-style: none; /* variables.css:86:3-14 */
+      border-bottom-width: 0; /* variables.css:86:3-14 */
+      border-right-style: none; /* variables.css:86:3-14 */
+      border-right-width: 0; /* variables.css:86:3-14 */
+      border-top-left-radius: 0; /* variables.css:86:3-14 */
+      border-top-right-radius: 0; /* variables.css:86:3-14 */
+      border-bottom-right-radius: 0; /* variables.css:86:3-14 */
+      border-bottom-left-radius: 0; /* variables.css:86:3-14 */
+      outline-style: none; /* variables.css:86:3-14 */
+      outline-width: 0; /* variables.css:86:3-14 */
+      outline-offset: 0; /* variables.css:86:3-14 */
+      background-clip: border-box; /* variables.css:86:3-14 */
+      background-origin: padding-box; /* variables.css:86:3-14 */
+      background-size: auto; /* variables.css:86:3-14 */
+      background-position: left top; /* variables.css:86:3-14 */
+      border-top-color: rgb(255,0,0); /* variables.css:86:3-14 */
+      border-right-color: rgb(255,0,0); /* variables.css:86:3-14 */
+      border-bottom-color: rgb(255,0,0); /* variables.css:86:3-14 */
+      border-left-color: rgb(255,0,0); /* variables.css:86:3-14 */
+      outline-color: rgb(255,0,0); /* variables.css:86:3-14 */
+      background-repeat: repeat; /* variables.css:86:3-14 */
+      background-image: none; /* variables.css:86:3-14 */
+      background-blend-mode: normal; /* variables.css:86:3-14 */
+      border-image-source: none; /* variables.css:86:3-14 */
+      border-image-repeat: stretch; /* variables.css:86:3-14 */
+      border-image-slice: 100%; /* variables.css:86:3-14 */
+      border-image-width: 1; /* variables.css:86:3-14 */
+      -gtk-icon-source: none; /* variables.css:86:3-14 */
+      -gtk-icon-size: 16px; /* variables.css:86:3-14 */
+      -gtk-icon-shadow: none; /* variables.css:86:3-14 */
+      -gtk-icon-style: requested; /* variables.css:86:3-14 */
+      -gtk-icon-transform: none; /* variables.css:86:3-14 */
+      -gtk-icon-filter: none; /* variables.css:86:3-14 */
+      border-spacing: 0 0; /* variables.css:86:3-14 */
+      transform: none; /* variables.css:86:3-14 */
+      transform-origin: center; /* variables.css:86:3-14 */
+      min-width: 0; /* variables.css:86:3-14 */
+      min-height: 0; /* variables.css:86:3-14 */
+      transition-property: all; /* variables.css:86:3-14 */
+      transition-duration: 0; /* variables.css:86:3-14 */
+      transition-timing-function: ease; /* variables.css:86:3-14 */
+      transition-delay: 0; /* variables.css:86:3-14 */
+      animation-name: none; /* variables.css:86:3-14 */
+      animation-duration: 0; /* variables.css:86:3-14 */
+      animation-timing-function: ease; /* variables.css:86:3-14 */
+      animation-iteration-count: 1; /* variables.css:86:3-14 */
+      animation-direction: normal; /* variables.css:86:3-14 */
+      animation-play-state: running; /* variables.css:86:3-14 */
+      animation-delay: 0; /* variables.css:86:3-14 */
+      animation-fill-mode: none; /* variables.css:86:3-14 */
+      opacity: 1; /* variables.css:86:3-14 */
+      filter: none; /* variables.css:86:3-14 */
+      caret-color: rgb(255,255,255); /* variables.css:86:3-14 */
+      -gtk-secondary-caret-color: rgb(255,255,255); /* variables.css:86:3-14 */
+      font-feature-settings: normal; /* variables.css:86:3-14 */
+      font-variation-settings: normal; /* variables.css:86:3-14 */
+      line-height: normal; /* variables.css:86:3-14 */
+      --color1: red; /* variables.css:2:3-17 */
+      --not-a-color: 20px; /* variables.css:3:3-23 */
+    label.label-7:dir(ltr)
+      color: rgb(255,0,0); /* variables.css:94:3-39 */
+      background-color: rgba(0,0,0,0); /* variables.css:101:3-40 */
+      --color1: red; /* variables.css:2:3-17 */
+      --not-a-color: 20px; /* variables.css:3:3-23 */
+    label.label-8:dir(ltr)
+      color: rgb(255,0,0); /* variables.css:136:3-31 */
+      background-color: rgb(0,0,255); /* variables.css:139:3-42 */
+      box-shadow: 0 0 3px rgb(255,255,0) inset; /* variables.css:142:3-50 */
+      padding-left: 1px; /* variables.css:124:3-19 */
+      padding-right: 10px; /* variables.css:125:3-20 */
+      transition-duration: 5s; /* variables.css:146:3-45 */
+      animation-name: test; /* variables.css:131:3-39 */
+      animation-duration: 10s; /* variables.css:131:3-39 */
+      animation-timing-function: linear; /* variables.css:131:3-39 */
+      animation-iteration-count: infinite; /* variables.css:131:3-39 */
+      animation-direction: normal; /* variables.css:131:3-39 */
+      animation-delay: 0; /* variables.css:131:3-39 */
+      animation-fill-mode: none; /* variables.css:131:3-39 */
+      --duration: 2s;
+      --duration2: var(--duration, 4s); /* variables.css:145:3-36 */
+      --padding-right: 10px;
+      --padding1: 1px; /* variables.css:127:3-19 */
+      --padding2: 2px; /* variables.css:128:3-19 */
+      --test1: red;
+      --test2: blue;

testsuite/css/style/variables.ui

@@ -0,0 +1,75 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <object class="GtkWindow" id="window1">
+    <property name="can_focus">False</property>
+    <property name="decorated">0</property>
+    <child>
+      <object class="GtkBox">
+        <child>
+          <object class="GtkLabel">
+            <property name="label" translatable="yes">Hello World!</property>
+            <style>
+              <class name="label-1"/>
+            </style>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label" translatable="yes">Hello World!</property>
+            <style>
+              <class name="label-2"/>
+            </style>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label" translatable="yes">Hello World!</property>
+            <style>
+              <class name="label-3"/>
+            </style>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label" translatable="yes">Hello World!</property>
+            <style>
+              <class name="label-4"/>
+            </style>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label" translatable="yes">Hello World!</property>
+            <style>
+              <class name="label-5"/>
+            </style>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label" translatable="yes">Hello World!</property>
+            <style>
+              <class name="label-6"/>
+            </style>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label" translatable="yes">Hello World!</property>
+            <style>
+              <class name="label-7"/>
+            </style>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label" translatable="yes">Hello World!</property>
+            <style>
+              <class name="label-8"/>
+            </style>
+          </object>
+        </child>
+      </object>
+    </child>
+  </object>
+</interface>

testsuite/css/transition.c

@@ -223,16 +223,16 @@ test_transition (gconstpointer data)
 
   value1 = value_from_string (prop, test->value1);
   g_assert_nonnull (value1);
-  computed1 = _gtk_css_value_compute (value1, test->prop, provider, style, NULL);
+  computed1 = _gtk_css_value_compute (value1, test->prop, provider, style, NULL, NULL);
 
   value2 = value_from_string (prop, test->value2);
   g_assert_nonnull (value2);
-  computed2 = _gtk_css_value_compute (value2, test->prop, provider, style, NULL);
+  computed2 = _gtk_css_value_compute (value2, test->prop, provider, style, NULL, NULL);
 
   if (test->value3)
     {
       value3 = value_from_string (prop, test->value3);
-      computed3 = _gtk_css_value_compute (value3, test->prop, provider, style, NULL);
+      computed3 = _gtk_css_value_compute (value3, test->prop, provider, style, NULL, NULL);
     }
   else
     {