gtk2/gtk/gtkcssselector.c

/* GTK - The GIMP Toolkit
 * Copyright (C) 2011 Benjamin Otte <otte@gnome.org>
 *
 * 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 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/>.
 */

#include "config.h"

#include "gtkcssselectorprivate.h"

#include <stdlib.h>
#include <string.h>

#include "gtkcssprovider.h"
#include "gtkstylecontextprivate.h"

#include <errno.h>
#if defined(_MSC_VER) && _MSC_VER >= 1500
# include <intrin.h>
#endif

typedef struct _GtkCssSelectorClass GtkCssSelectorClass;
typedef gboolean (* GtkCssSelectorForeachFunc) (const GtkCssSelector *selector,
                                                const GtkCssMatcher  *matcher,
                                                gpointer              data);

struct _GtkCssSelectorClass {
  const char        *name;

  void              (* print)       (const GtkCssSelector       *selector,
                                     GString                    *string);
  /* NULL or an iterator that calls func with each submatcher of @matcher.
   * Potentially no submatcher exists.
   * If any @invocation of @func returns %TRUE, the function will immediately
   * return %TRUE itself. If @func never returns %TRUE (or isn't called at all),
   * %FALSE will be returned.
   */
  gboolean          (* foreach_matcher)  (const GtkCssSelector       *selector,
                                          const GtkCssMatcher        *matcher,
                                          GtkCssSelectorForeachFunc   func,
                                          gpointer                    data);
  gboolean          (* match_one)   (const GtkCssSelector       *selector,
                                     const GtkCssMatcher        *matcher);
  GtkCssChange      (* get_change)  (const GtkCssSelector       *selector,
				     GtkCssChange                previous_change);
  void              (* add_specificity)  (const GtkCssSelector  *selector,
                                          guint                 *ids,
                                          guint                 *classes,
                                          guint                 *elements);
  guint             (* hash_one)    (const GtkCssSelector       *selector);
  int               (* compare_one) (const GtkCssSelector       *a,
				     const GtkCssSelector       *b);

  guint         is_simple :1;
};

typedef enum {
  POSITION_FORWARD,
  POSITION_BACKWARD,
  POSITION_ONLY,
} PositionType;
#define POSITION_TYPE_BITS 4
#define POSITION_NUMBER_BITS ((sizeof (gpointer) * 8 - POSITION_TYPE_BITS) / 2)

union _GtkCssSelector
{
  const GtkCssSelectorClass     *class;         /* type of check this selector does */
  struct {
    const GtkCssSelectorClass   *class;
    const char                  *name;          /* interned */
  }                              id;
  struct {
    const GtkCssSelectorClass   *class;
    GQuark                       style_class;
  }                              style_class;
  struct {
    const GtkCssSelectorClass   *class;
    const char                  *name;          /* interned */
  }                              name;
  struct {
    const GtkCssSelectorClass   *class;
    GtkStateFlags                state;
  }                              state;
  struct {
    const GtkCssSelectorClass   *class;
    PositionType                 type :POSITION_TYPE_BITS;
    gssize                       a :POSITION_NUMBER_BITS;
    gssize                       b :POSITION_NUMBER_BITS;
  }                              position;
};

#define GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET G_MAXINT32
struct _GtkCssSelectorTree
{
  GtkCssSelector selector;
  gint32 parent_offset;
  gint32 previous_offset;
  gint32 sibling_offset;
  gint32 matches_offset; /* pointers that we return as matches if selector matches */
};

static gboolean
gtk_css_selector_equal (const GtkCssSelector *a,
			const GtkCssSelector *b)
{
  return
    a->class == b->class &&
    a->class->compare_one (a, b) == 0;
}

static guint
gtk_css_selector_hash_one (const GtkCssSelector *selector)
{
  return GPOINTER_TO_UINT (selector->class) ^ selector->class->hash_one (selector);
}

static gpointer *
gtk_css_selector_tree_get_matches (const GtkCssSelectorTree *tree)
{
  if (tree->matches_offset == GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET)
    return NULL;

  return (gpointer *) ((guint8 *)tree + tree->matches_offset);
}

static void
g_ptr_array_insert_sorted (GPtrArray *array,
                           gpointer   data)
{
  gint i;

  for (i = 0; i < array->len; i++)
    {
      if (data == array->pdata[i])
        return;

      if (data < array->pdata[i])
        break;
    }

  g_ptr_array_insert (array, i, data);
}

static void
gtk_css_selector_tree_found_match (const GtkCssSelectorTree  *tree,
				   GPtrArray                **array)
{
  int i;
  gpointer *matches;

  matches = gtk_css_selector_tree_get_matches (tree);
  if (matches)
    {
      if (!*array)
        *array = g_ptr_array_sized_new (16);

      for (i = 0; matches[i] != NULL; i++)
        g_ptr_array_insert_sorted (*array, matches[i]);
    }
}

static gboolean
gtk_css_selector_match (const GtkCssSelector *selector,
                        const GtkCssMatcher  *matcher)
{
  return selector->class->match_one (selector, matcher);
}

static gboolean
gtk_css_selector_foreach (const GtkCssSelector      *selector,
                          const GtkCssMatcher       *matcher,
                          GtkCssSelectorForeachFunc  func,
                          gpointer                   data)
{
  return selector->class->foreach_matcher (selector, matcher, func, data);
}

static int
gtk_css_selector_compare_one (const GtkCssSelector *a, const GtkCssSelector *b)
{
  if (a->class != b->class)
    return strcmp (a->class->name, b->class->name);
  else
    return a->class->compare_one (a, b);
}
  
static const GtkCssSelector *
gtk_css_selector_previous (const GtkCssSelector *selector)
{
  selector = selector + 1;

  return selector->class ? selector : NULL;
}

static const GtkCssSelectorTree *
gtk_css_selector_tree_at_offset (const GtkCssSelectorTree *tree,
				 gint32 offset)
{
  if (offset == GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET)
    return NULL;

  return (GtkCssSelectorTree *) ((guint8 *)tree + offset);
}

static const GtkCssSelectorTree *
gtk_css_selector_tree_get_parent (const GtkCssSelectorTree *tree)
{
  return gtk_css_selector_tree_at_offset (tree, tree->parent_offset);
}

static const GtkCssSelectorTree *
gtk_css_selector_tree_get_previous (const GtkCssSelectorTree *tree)
{
  return gtk_css_selector_tree_at_offset (tree, tree->previous_offset);
}

static const GtkCssSelectorTree *
gtk_css_selector_tree_get_sibling (const GtkCssSelectorTree *tree)
{
  return gtk_css_selector_tree_at_offset (tree, tree->sibling_offset);
}

/* DEFAULTS */

static void
gtk_css_selector_default_add_specificity (const GtkCssSelector *selector,
                                          guint                *ids,
                                          guint                *classes,
                                          guint                *elements)
{
  /* no specificity changes */
}
 
static gboolean
gtk_css_selector_default_foreach_matcher (const GtkCssSelector       *selector,
                                          const GtkCssMatcher        *matcher,
                                          GtkCssSelectorForeachFunc   func,
                                          gpointer                    data)
{
  return func (selector, matcher, data);
}

static gboolean
gtk_css_selector_default_match_one (const GtkCssSelector *selector,
                                    const GtkCssMatcher  *matcher)
{
  return TRUE;
}

static guint
gtk_css_selector_default_hash_one (const GtkCssSelector *selector)
{
  return 0;
}

static int
gtk_css_selector_default_compare_one (const GtkCssSelector *a,
                                      const GtkCssSelector *b)
{
  return 0;
}

/* DESCENDANT */

static void
gtk_css_selector_descendant_print (const GtkCssSelector *selector,
                                   GString              *string)
{
  g_string_append_c (string, ' ');
}

static gboolean
gtk_css_selector_descendant_foreach_matcher (const GtkCssSelector      *selector,
                                             const GtkCssMatcher       *matcher,
                                             GtkCssSelectorForeachFunc  func,
                                             gpointer                   data)
{
  GtkCssMatcher ancestor;

  while (_gtk_css_matcher_get_parent (&ancestor, matcher))
    {
      matcher = &ancestor;

      if (func (selector, &ancestor, data))
        return TRUE;

      /* any matchers are dangerous here, as we may loop forever, but
	 we can terminate now as all possible matches have already been added */
      if (_gtk_css_matcher_matches_any (matcher))
	break;
    }

  return FALSE;
}

static GtkCssChange
gtk_css_selector_descendant_get_change (const GtkCssSelector *selector, GtkCssChange previous_change)
{
  return _gtk_css_change_for_child (previous_change);
}

static const GtkCssSelectorClass GTK_CSS_SELECTOR_DESCENDANT = {
  "descendant",
  gtk_css_selector_descendant_print,
  gtk_css_selector_descendant_foreach_matcher,
  gtk_css_selector_default_match_one,
  gtk_css_selector_descendant_get_change,
  gtk_css_selector_default_add_specificity,
  gtk_css_selector_default_hash_one,
  gtk_css_selector_default_compare_one,
  FALSE
};

/* CHILD */

static void
gtk_css_selector_child_print (const GtkCssSelector *selector,
                              GString              *string)
{
  g_string_append (string, " > ");
}

static gboolean
gtk_css_selector_child_foreach_matcher (const GtkCssSelector      *selector,
                                        const GtkCssMatcher       *matcher,
                                        GtkCssSelectorForeachFunc  func,
                                        gpointer                   data)
{
  GtkCssMatcher parent;

  if (!_gtk_css_matcher_get_parent (&parent, matcher))
    return FALSE;

  return func (selector, &parent, data);
}

static GtkCssChange
gtk_css_selector_child_get_change (const GtkCssSelector *selector, GtkCssChange previous_change)
{
  return _gtk_css_change_for_child (previous_change);
}

static const GtkCssSelectorClass GTK_CSS_SELECTOR_CHILD = {
  "child",
  gtk_css_selector_child_print,
  gtk_css_selector_child_foreach_matcher,
  gtk_css_selector_default_match_one,
  gtk_css_selector_child_get_change,
  gtk_css_selector_default_add_specificity,
  gtk_css_selector_default_hash_one,
  gtk_css_selector_default_compare_one,
  FALSE
};

/* SIBLING */

static void
gtk_css_selector_sibling_print (const GtkCssSelector *selector,
                                GString              *string)
{
  g_string_append (string, " ~ ");
}

static gboolean
gtk_css_selector_sibling_foreach_matcher (const GtkCssSelector      *selector,
                                          const GtkCssMatcher       *matcher,
                                          GtkCssSelectorForeachFunc  func,
                                          gpointer                   data)
{
  GtkCssMatcher previous;

  while (_gtk_css_matcher_get_previous (&previous, matcher))
    {
      matcher = &previous;

      if (func (selector, matcher, data))
        return TRUE;

      /* any matchers are dangerous here, as we may loop forever, but
	 we can terminate now as all possible matches have already been added */
      if (_gtk_css_matcher_matches_any (matcher))
	break;
    }

  return FALSE;
}

static GtkCssChange
gtk_css_selector_sibling_get_change (const GtkCssSelector *selector, GtkCssChange previous_change)
{
  return _gtk_css_change_for_sibling (previous_change);
}

static const GtkCssSelectorClass GTK_CSS_SELECTOR_SIBLING = {
  "sibling",
  gtk_css_selector_sibling_print,
  gtk_css_selector_sibling_foreach_matcher,
  gtk_css_selector_default_match_one,
  gtk_css_selector_sibling_get_change,
  gtk_css_selector_default_add_specificity,
  gtk_css_selector_default_hash_one,
  gtk_css_selector_default_compare_one,
  FALSE
};

/* ADJACENT */

static void
gtk_css_selector_adjacent_print (const GtkCssSelector *selector,
                                 GString              *string)
{
  g_string_append (string, " + ");
}

static gboolean
gtk_css_selector_adjacent_foreach_matcher (const GtkCssSelector      *selector,
                                           const GtkCssMatcher       *matcher,
                                           GtkCssSelectorForeachFunc  func,
                                           gpointer                   data)
{
  GtkCssMatcher previous;

  if (!_gtk_css_matcher_get_previous (&previous, matcher))
    return FALSE;
  
  return func (selector, &previous, data);
}

static GtkCssChange
gtk_css_selector_adjacent_get_change (const GtkCssSelector *selector, GtkCssChange previous_change)
{
  return _gtk_css_change_for_sibling (previous_change);
}

static const GtkCssSelectorClass GTK_CSS_SELECTOR_ADJACENT = {
  "adjacent",
  gtk_css_selector_adjacent_print,
  gtk_css_selector_adjacent_foreach_matcher,
  gtk_css_selector_default_match_one,
  gtk_css_selector_adjacent_get_change,
  gtk_css_selector_default_add_specificity,
  gtk_css_selector_default_hash_one,
  gtk_css_selector_default_compare_one,
  FALSE
};

/* SIMPLE SELECTOR DEFINE */

#define DEFINE_SIMPLE_SELECTOR(n, \
                               c, \
                               print_func, \
                               match_func, \
                               hash_func, \
                               comp_func, \
                               increase_id_specificity, \
                               increase_class_specificity, \
                               increase_element_specificity) \
static void \
gtk_css_selector_ ## n ## _print (const GtkCssSelector *selector, \
                                    GString              *string) \
{ \
  print_func (selector, string); \
} \
\
static void \
gtk_css_selector_not_ ## n ## _print (const GtkCssSelector *selector, \
                                      GString              *string) \
{ \
  g_string_append (string, ":not("); \
  print_func (selector, string); \
  g_string_append (string, ")"); \
} \
\
static gboolean \
gtk_css_selector_not_ ## n ## _match_one (const GtkCssSelector *selector, \
                                          const GtkCssMatcher  *matcher) \
{ \
  return !match_func (selector, matcher); \
} \
\
static GtkCssChange \
gtk_css_selector_ ## n ## _get_change (const GtkCssSelector *selector, GtkCssChange previous_change) \
{ \
  return previous_change | GTK_CSS_CHANGE_ ## c; \
} \
\
static void \
gtk_css_selector_ ## n ## _add_specificity (const GtkCssSelector *selector, \
                                            guint                *ids, \
                                            guint                *classes, \
                                            guint                *elements) \
{ \
  if (increase_id_specificity) \
    { \
      (*ids)++; \
    } \
  if (increase_class_specificity) \
    { \
      (*classes)++; \
    } \
  if (increase_element_specificity) \
    { \
      (*elements)++; \
    } \
} \
\
static const GtkCssSelectorClass GTK_CSS_SELECTOR_ ## c = { \
  G_STRINGIFY(n), \
  gtk_css_selector_ ## n ## _print, \
  gtk_css_selector_default_foreach_matcher, \
  match_func, \
  gtk_css_selector_ ## n ## _get_change, \
  gtk_css_selector_ ## n ## _add_specificity, \
  hash_func, \
  comp_func, \
  TRUE \
};\
\
static const GtkCssSelectorClass GTK_CSS_SELECTOR_NOT_ ## c = { \
  "not_" G_STRINGIFY(n), \
  gtk_css_selector_not_ ## n ## _print, \
  gtk_css_selector_default_foreach_matcher, \
  gtk_css_selector_not_ ## n ## _match_one, \
  gtk_css_selector_ ## n ## _get_change, \
  gtk_css_selector_ ## n ## _add_specificity, \
  hash_func, \
  comp_func, \
  TRUE \
};

/* ANY */

static void
print_any (const GtkCssSelector *selector,
           GString              *string)
{
  g_string_append_c (string, '*');
}

static gboolean
match_any (const GtkCssSelector *selector,
           const GtkCssMatcher  *matcher)
{
  return TRUE;
}

#undef GTK_CSS_CHANGE_ANY
#define GTK_CSS_CHANGE_ANY 0
DEFINE_SIMPLE_SELECTOR(any, ANY, print_any, match_any, 
                       gtk_css_selector_default_hash_one, gtk_css_selector_default_compare_one,
                       FALSE, FALSE, FALSE)
#undef GTK_CSS_CHANGE_ANY

/* NAME */

static void
print_name (const GtkCssSelector *selector,
            GString              *string)
{
  g_string_append (string, selector->name.name);
}

static gboolean
match_name (const GtkCssSelector *selector,
            const GtkCssMatcher  *matcher)
{
  return _gtk_css_matcher_has_name (matcher, selector->name.name);
}

static guint
hash_name (const GtkCssSelector *a)
{
  return g_str_hash (a->name.name);
}

static int
comp_name (const GtkCssSelector *a,
           const GtkCssSelector *b)
{
  return strcmp (a->name.name,
		 b->name.name);
}

DEFINE_SIMPLE_SELECTOR(name, NAME, print_name, match_name, hash_name, comp_name, FALSE, FALSE, TRUE)

/* CLASS */

static void
print_class (const GtkCssSelector *selector,
             GString              *string)
{
  g_string_append_c (string, '.');
  g_string_append (string, g_quark_to_string (selector->style_class.style_class));
}

static gboolean
match_class (const GtkCssSelector *selector,
             const GtkCssMatcher  *matcher)
{
  return _gtk_css_matcher_has_class (matcher, selector->style_class.style_class);
}

static guint
hash_class (const GtkCssSelector *a)
{
  return a->style_class.style_class;
}

static int
comp_class (const GtkCssSelector *a,
            const GtkCssSelector *b)
{
  if (a->style_class.style_class < b->style_class.style_class)
    return -1;
  if (a->style_class.style_class > b->style_class.style_class)
    return 1;
  else
    return 0;
}

DEFINE_SIMPLE_SELECTOR(class, CLASS, print_class, match_class, hash_class, comp_class, FALSE, TRUE, FALSE)

/* ID */

static void
print_id (const GtkCssSelector *selector,
          GString              *string)
{
  g_string_append_c (string, '#');
  g_string_append (string, selector->id.name);
}

static gboolean
match_id (const GtkCssSelector *selector,
          const GtkCssMatcher  *matcher)
{
  return _gtk_css_matcher_has_id (matcher, selector->id.name);
}

static guint
hash_id (const GtkCssSelector *a)
{
  return GPOINTER_TO_UINT (a->id.name);
}

static int
comp_id (const GtkCssSelector *a,
	 const GtkCssSelector *b)
{
  if (a->id.name < b->id.name)
    return -1;
  else if (a->id.name > b->id.name)
    return 1;
  else
    return 0;
}

DEFINE_SIMPLE_SELECTOR(id, ID, print_id, match_id, hash_id, comp_id, TRUE, FALSE, FALSE)

const gchar *
gtk_css_pseudoclass_name (GtkStateFlags state)
{
  static const char * state_names[] = {
    "active",
    "hover",
    "selected",
    "disabled",
    "indeterminate",
    "focus",
    "backdrop",
    "dir(ltr)",
    "dir(rtl)",
    "link",
    "visited",
    "checked",
    "drop(active)",
    "focus(visible)"
  };
  guint i;

  for (i = 0; i < G_N_ELEMENTS (state_names); i++)
    {
      if (state == (1 << i))
        return state_names[i];
    }

  return NULL;
}

/* PSEUDOCLASS FOR STATE */
static void
print_pseudoclass_state (const GtkCssSelector *selector,
                         GString              *string)
{
  g_string_append_c (string, ':');
  g_string_append (string, gtk_css_pseudoclass_name (selector->state.state));
}

static gboolean
match_pseudoclass_state (const GtkCssSelector *selector,
                         const GtkCssMatcher  *matcher)
{
  return (_gtk_css_matcher_get_state (matcher) & selector->state.state) == selector->state.state;
}

static guint
hash_pseudoclass_state (const GtkCssSelector *selector)
{
  return selector->state.state;
}


static int
comp_pseudoclass_state (const GtkCssSelector *a,
		        const GtkCssSelector *b)
{
  return a->state.state - b->state.state;
}

#define GTK_CSS_CHANGE_PSEUDOCLASS_STATE GTK_CSS_CHANGE_STATE
DEFINE_SIMPLE_SELECTOR(pseudoclass_state, PSEUDOCLASS_STATE, print_pseudoclass_state,
                       match_pseudoclass_state, hash_pseudoclass_state, comp_pseudoclass_state,
                       FALSE, TRUE, FALSE)
#undef GTK_CSS_CHANGE_PSEUDOCLASS_STATE

/* PSEUDOCLASS FOR POSITION */

static void
print_pseudoclass_position (const GtkCssSelector *selector,
                            GString              *string)
{
  switch (selector->position.type)
    {
    case POSITION_FORWARD:
      if (selector->position.a == 0)
        {
          if (selector->position.b == 1)
            g_string_append (string, ":first-child");
          else
            g_string_append_printf (string, ":nth-child(%d)", selector->position.b);
        }
      else if (selector->position.a == 2 && selector->position.b == 0)
        g_string_append (string, ":nth-child(even)");
      else if (selector->position.a == 2 && selector->position.b == 1)
        g_string_append (string, ":nth-child(odd)");
      else
        {
          g_string_append (string, ":nth-child(");
          if (selector->position.a == 1)
            g_string_append (string, "n");
          else if (selector->position.a == -1)
            g_string_append (string, "-n");
          else
            g_string_append_printf (string, "%dn", selector->position.a);
          if (selector->position.b > 0)
            g_string_append_printf (string, "+%d)", selector->position.b);
          else if (selector->position.b < 0)
            g_string_append_printf (string, "%d)", selector->position.b);
          else
            g_string_append (string, ")");
        }
      break;
    case POSITION_BACKWARD:
      if (selector->position.a == 0)
        {
          if (selector->position.b == 1)
            g_string_append (string, ":last-child");
          else
            g_string_append_printf (string, ":nth-last-child(%d)", selector->position.b);
        }
      else if (selector->position.a == 2 && selector->position.b == 0)
        g_string_append (string, ":nth-last-child(even)");
      else if (selector->position.a == 2 && selector->position.b == 1)
        g_string_append (string, ":nth-last-child(odd)");
      else
        {
          g_string_append (string, ":nth-last-child(");
          if (selector->position.a == 1)
            g_string_append (string, "n");
          else if (selector->position.a == -1)
            g_string_append (string, "-n");
          else
            g_string_append_printf (string, "%dn", selector->position.a);
          if (selector->position.b > 0)
            g_string_append_printf (string, "+%d)", selector->position.b);
          else if (selector->position.b < 0)
            g_string_append_printf (string, "%d)", selector->position.b);
          else
            g_string_append (string, ")");
        }
      break;
    case POSITION_ONLY:
      g_string_append (string, ":only-child");
      break;
    default:
      g_assert_not_reached ();
      break;
    }
}

static gboolean
match_pseudoclass_position (const GtkCssSelector *selector,
		            const GtkCssMatcher  *matcher)
{
  switch (selector->position.type)
    {
    case POSITION_FORWARD:
      if (!_gtk_css_matcher_has_position (matcher, TRUE, selector->position.a, selector->position.b))
        return FALSE;
      break;
    case POSITION_BACKWARD:
      if (!_gtk_css_matcher_has_position (matcher, FALSE, selector->position.a, selector->position.b))
        return FALSE;
      break;
    case POSITION_ONLY:
      if (!_gtk_css_matcher_has_position (matcher, TRUE, 0, 1) ||
          !_gtk_css_matcher_has_position (matcher, FALSE, 0, 1))
        return FALSE;
      break;
    default:
      g_assert_not_reached ();
      return FALSE;
    }

  return TRUE;
}

static guint
hash_pseudoclass_position (const GtkCssSelector *a)
{
  return (guint)(((((gulong)a->position.type) << POSITION_NUMBER_BITS) | a->position.a) << POSITION_NUMBER_BITS) | a->position.b;
}

static int
comp_pseudoclass_position (const GtkCssSelector *a,
			   const GtkCssSelector *b)
{
  int diff;
  
  diff = a->position.type - b->position.type;
  if (diff)
    return diff;

  diff = a->position.a - b->position.a;
  if (diff)
    return diff;

  return a->position.b - b->position.b;
}

static GtkCssChange
change_pseudoclass_position (const GtkCssSelector *selector)
{
  switch (selector->position.type)
    {
    case POSITION_FORWARD:
      if (selector->position.a == 0 && selector->position.b == 1)
        return GTK_CSS_CHANGE_FIRST_CHILD;
      else
        return GTK_CSS_CHANGE_NTH_CHILD;
    case POSITION_BACKWARD:
      if (selector->position.a == 0 && selector->position.b == 1)
        return GTK_CSS_CHANGE_LAST_CHILD;
      else
        return GTK_CSS_CHANGE_NTH_LAST_CHILD;
    case POSITION_ONLY:
      return GTK_CSS_CHANGE_FIRST_CHILD | GTK_CSS_CHANGE_LAST_CHILD;
    default:
      g_assert_not_reached ();
      return 0;
    }
}

#define GTK_CSS_CHANGE_PSEUDOCLASS_POSITION change_pseudoclass_position(selector)
DEFINE_SIMPLE_SELECTOR(pseudoclass_position, PSEUDOCLASS_POSITION, print_pseudoclass_position,
                       match_pseudoclass_position, hash_pseudoclass_position, comp_pseudoclass_position,
                       FALSE, TRUE, FALSE)
#undef GTK_CSS_CHANGE_PSEUDOCLASS_POSITION
/* API */

static guint
gtk_css_selector_size (const GtkCssSelector *selector)
{
  guint size = 0;

  while (selector)
    {
      selector = gtk_css_selector_previous (selector);
      size++;
    }

  return size;
}

static GtkCssSelector *
gtk_css_selector_new (const GtkCssSelectorClass *class,
                      GtkCssSelector            *selector)
{
  guint size;

  size = gtk_css_selector_size (selector);
  selector = g_realloc (selector, sizeof (GtkCssSelector) * (size + 1) + sizeof (gpointer));
  if (size == 0)
    selector[1].class = NULL;
  else
    memmove (selector + 1, selector, sizeof (GtkCssSelector) * size + sizeof (gpointer));

  memset (selector, 0, sizeof (GtkCssSelector));
  selector->class = class;

  return selector;
}

static GtkCssSelector *
gtk_css_selector_parse_selector_class (GtkCssParser   *parser,
                                       GtkCssSelector *selector,
                                       gboolean        negate)
{
  const GtkCssToken *token;

  gtk_css_parser_consume_token (parser);
  for (token = gtk_css_parser_peek_token (parser);
       gtk_css_token_is (token, GTK_CSS_TOKEN_COMMENT);
       token = gtk_css_parser_peek_token (parser))
    {
      gtk_css_parser_consume_token (parser);
    }

  if (gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT))
    {
      selector = gtk_css_selector_new (negate ? &GTK_CSS_SELECTOR_NOT_CLASS
                                              : &GTK_CSS_SELECTOR_CLASS,
                                       selector);
      selector->style_class.style_class = g_quark_from_string (token->string.string);
      gtk_css_parser_consume_token (parser);
      return selector;
    }
  else
    {
      gtk_css_parser_error_syntax (parser, "No class name after '.' in selector");
      if (selector)
        _gtk_css_selector_free (selector);
      return NULL;
    }
}

static gboolean
string_has_number (const char *string,
                   const char *prefix,
                   int        *number)
{
  gsize len = strlen (prefix);
  char *end;

  if (g_ascii_strncasecmp (string, prefix, len) != 0)
    return FALSE;

  errno = 0;
  *number = strtoul (string + len, &end, 10);
  if (*end != '\0' || errno != 0)
    return FALSE;

  return TRUE;
}

static gboolean
parse_plus_b (GtkCssParser *parser,
              gboolean      negate,
              gint         *b)
{
  const GtkCssToken *token;
  gboolean has_seen_sign;

  token = gtk_css_parser_get_token (parser);

  if (negate)
    {
      has_seen_sign = TRUE;
    }
  else
    {
      if (gtk_css_token_is_delim (token, '+'))
        {
          gtk_css_parser_consume_token (parser);
          has_seen_sign = TRUE;
        }
      else if (gtk_css_token_is_delim (token, '-'))
        {
          gtk_css_parser_consume_token (parser);
          negate = TRUE;
          has_seen_sign = TRUE;
        }
      else
        {
          has_seen_sign = FALSE;
        }
    }

  token = gtk_css_parser_get_token (parser);
  if (!has_seen_sign && gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNED_INTEGER))
    {
      *b = token->number.number;
      gtk_css_parser_consume_token (parser);
      return TRUE;
    }
  else if (has_seen_sign && gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNLESS_INTEGER))
    {
      *b = token->number.number;
      if (negate)
        *b = - *b;
      gtk_css_parser_consume_token (parser);
      return TRUE;
    }
  else if (!has_seen_sign)
    {
      *b = 0;
      return TRUE;
    }
  
  gtk_css_parser_error_syntax (parser, "Not a valid an+b type");
  return FALSE;
}

static gboolean
parse_n_plus_b (GtkCssParser *parser,
                gint          before,
                gint         *a,
                gint         *b)
{
  const GtkCssToken *token;

  token = gtk_css_parser_get_token (parser);

  if (gtk_css_token_is_ident (token, "n"))
    {
      *a = before;
      gtk_css_parser_consume_token (parser);
      return parse_plus_b (parser, FALSE, b);
    }
  else if (gtk_css_token_is_ident (token, "n-"))
    {
      *a = before;
      gtk_css_parser_consume_token (parser);
      return parse_plus_b (parser, TRUE, b);
    }
  else if (gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT) &&
           string_has_number (token->string.string, "n-", b))
    {
      *a = before;
      *b = -*b;
      gtk_css_parser_consume_token (parser);
      return TRUE;
    }
  else
    {
      *b = before;
      *a = 0;
      return TRUE;
    }
  
  gtk_css_parser_error_syntax (parser, "Not a valid an+b type");
  return FALSE;
}
                
static gboolean
parse_a_n_plus_b (GtkCssParser *parser,
                  gint          seen_sign,
                  gint         *a,
                  gint         *b)
{
  const GtkCssToken *token;

  token = gtk_css_parser_get_token (parser);

  if (!seen_sign && gtk_css_token_is_ident (token, "even"))
    {
      *a = 2;
      *b = 0;
      gtk_css_parser_consume_token (parser);
      return TRUE;
    }
  else if (!seen_sign && gtk_css_token_is_ident (token, "odd"))
    {
      *a = 2;
      *b = 1;
      gtk_css_parser_consume_token (parser);
      return TRUE;
    }
  else if (!seen_sign && gtk_css_token_is_delim (token, '+'))
    {
      gtk_css_parser_consume_token (parser);
      return parse_a_n_plus_b (parser, 1, a, b);
    }
  else if (!seen_sign && gtk_css_token_is_delim (token, '-'))
    {
      gtk_css_parser_consume_token (parser);
      return parse_a_n_plus_b (parser, -1, a, b);
    }
  else if ((!seen_sign && gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNED_INTEGER)) ||
           gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNLESS_INTEGER))
    {
      int x = token->number.number * (seen_sign ? seen_sign : 1);
      gtk_css_parser_consume_token (parser);

      return parse_n_plus_b (parser, x , a, b);
    }
  else if (((!seen_sign && gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNED_INTEGER_DIMENSION)) ||
            gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNLESS_INTEGER_DIMENSION)) &&
           g_ascii_strcasecmp (token->dimension.dimension, "n") == 0)
    {
      *a = token->dimension.value * (seen_sign ? seen_sign : 1);
      gtk_css_parser_consume_token (parser);
      return parse_plus_b (parser, FALSE, b);
    }
  else if (((!seen_sign && gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNED_INTEGER_DIMENSION)) ||
            gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNLESS_INTEGER_DIMENSION)) &&
           g_ascii_strcasecmp (token->dimension.dimension, "n-") == 0)
    {
      *a = token->dimension.value * (seen_sign ? seen_sign : 1);
      gtk_css_parser_consume_token (parser);
      return parse_plus_b (parser, TRUE, b);
    }
  else if (((!seen_sign && gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNED_INTEGER_DIMENSION)) ||
            gtk_css_token_is (token, GTK_CSS_TOKEN_SIGNLESS_INTEGER_DIMENSION)) &&
           string_has_number (token->dimension.dimension, "n-", b))
    {
      *a = token->dimension.value * (seen_sign ? seen_sign : 1);
      *b = -*b;
      gtk_css_parser_consume_token (parser);
      return TRUE;
    }
  else if (!seen_sign && gtk_css_token_is_ident (token, "-n"))
    {
      *a = -1;
      gtk_css_parser_consume_token (parser);
      return parse_plus_b (parser, FALSE, b);
    }
  else if (!seen_sign && gtk_css_token_is_ident (token, "-n-"))
    {
      *a = -1;
      gtk_css_parser_consume_token (parser);
      return parse_plus_b (parser, TRUE, b);
    }
  else if (!seen_sign &&
           gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT) &&
           string_has_number (token->string.string, "-n-", b))
    {
      *a = -1;
      *b = -*b;
      gtk_css_parser_consume_token (parser);
      return TRUE;
    }
  else if (gtk_css_token_is_ident (token, "n") ||
           gtk_css_token_is_ident (token, "n-"))
    {
      return parse_n_plus_b (parser, seen_sign ? seen_sign : 1, a, b);
    }
  else if (gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT) &&
           string_has_number (token->string.string, "n-", b))
    {
      *a = seen_sign ? seen_sign : 1;
      *b = -*b;
      gtk_css_parser_consume_token (parser);
      return TRUE;
    }
  else if (!seen_sign && gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT) &&
           string_has_number (token->string.string, "-n-", b))
    {
      *a = -1;
      *b = -*b;
      gtk_css_parser_consume_token (parser);
      return TRUE;
    }
  
  gtk_css_parser_error_syntax (parser, "Not a valid an+b type");
  return FALSE;
}

static guint
parse_a_n_plus_b_arg (GtkCssParser *parser,
                      guint         arg,
                      gpointer      data)
{
  gint *ab = data;

  if (!parse_a_n_plus_b (parser, FALSE, &ab[0], &ab[1]))
    return 0;

  return 1;
}

static guint
parse_dir_arg (GtkCssParser *parser,
               guint         arg,
               gpointer      data)
{
  GtkStateFlags *flag = data;

  if (gtk_css_parser_try_ident (parser, "ltr"))
    {
      *flag = GTK_STATE_FLAG_DIR_LTR;
      return 1;
    }
  else if (gtk_css_parser_try_ident (parser, "rtl"))
    {
      *flag = GTK_STATE_FLAG_DIR_RTL;
      return 1;
    }
  else
    {
      gtk_css_parser_error_value (parser, "Expected \"ltr\" or \"rtl\"");
      return 0;
    }
}

static guint
parse_identifier_arg (GtkCssParser *parser,
                      guint         arg,
                      gpointer      data)
{
  const char *ident = data;
  
  if (!gtk_css_parser_try_ident (parser, ident))
    {
      gtk_css_parser_error_value (parser, "Expected \"%s\"", ident);
      return 0;
    }

  return 1;
}

static GtkCssSelector *
gtk_css_selector_parse_selector_pseudo_class (GtkCssParser   *parser,
                                              GtkCssSelector *selector,
                                              gboolean        negate)
{
  GtkCssLocation start_location;
  const GtkCssToken *token;

  start_location = *gtk_css_parser_get_start_location (parser);
  gtk_css_parser_consume_token (parser);
  for (token = gtk_css_parser_peek_token (parser);
       gtk_css_token_is (token, GTK_CSS_TOKEN_COMMENT);
       token = gtk_css_parser_peek_token (parser))
    {
      gtk_css_parser_consume_token (parser);
    }

  if (gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT))
    {
      static const struct {
        const char    *name;
        GtkStateFlags  state_flag;
        PositionType   position_type;
        int            position_a;
        int            position_b;
      } pseudo_classes[] = {
        { "first-child",    0,                           POSITION_FORWARD,  0, 1 },
        { "last-child",     0,                           POSITION_BACKWARD, 0, 1 },
        { "only-child",     0,                           POSITION_ONLY,     0, 0 },
        { "active",         GTK_STATE_FLAG_ACTIVE, },
        { "hover",          GTK_STATE_FLAG_PRELIGHT, },
        { "selected",       GTK_STATE_FLAG_SELECTED, },
        { "disabled",       GTK_STATE_FLAG_INSENSITIVE, },
        { "indeterminate",  GTK_STATE_FLAG_INCONSISTENT, },
        { "focus",          GTK_STATE_FLAG_FOCUSED, },
        { "backdrop",       GTK_STATE_FLAG_BACKDROP, },
        { "link",           GTK_STATE_FLAG_LINK, },
        { "visited",        GTK_STATE_FLAG_VISITED, },
        { "checked",        GTK_STATE_FLAG_CHECKED, },
      };
      guint i;

      for (i = 0; i < G_N_ELEMENTS (pseudo_classes); i++)
        {
          if (g_ascii_strcasecmp (pseudo_classes[i].name, token->string.string) == 0)
            {
              if (pseudo_classes[i].state_flag)
                {
                  selector = gtk_css_selector_new (negate ? &GTK_CSS_SELECTOR_NOT_PSEUDOCLASS_STATE
                                                          : &GTK_CSS_SELECTOR_PSEUDOCLASS_STATE,
                                                   selector);
                  selector->state.state = pseudo_classes[i].state_flag;
                }
              else
                {
                  selector = gtk_css_selector_new (negate ? &GTK_CSS_SELECTOR_NOT_PSEUDOCLASS_POSITION
                                                          : &GTK_CSS_SELECTOR_PSEUDOCLASS_POSITION,
                                                   selector);
                  selector->position.type = pseudo_classes[i].position_type;
                  selector->position.a = pseudo_classes[i].position_a;
                  selector->position.b = pseudo_classes[i].position_b;
                }
              gtk_css_parser_consume_token (parser);
              return selector;
            }
        }
          
      gtk_css_parser_error (parser,
                            GTK_CSS_PARSER_ERROR_UNKNOWN_VALUE,
                            &start_location,
                            gtk_css_parser_get_end_location (parser),
                            "Unknown name of pseudo-class");
      if (selector)
        _gtk_css_selector_free (selector);
      return NULL;
    }
  else if (gtk_css_token_is (token, GTK_CSS_TOKEN_FUNCTION))
    {
      if (gtk_css_token_is_function (token, "nth-child"))
        {
          gint ab[2];

          if (!gtk_css_parser_consume_function (parser, 1, 1, parse_a_n_plus_b_arg, ab))
            {
              if (selector)
                _gtk_css_selector_free (selector);
              return NULL;
            }

          selector = gtk_css_selector_new (negate ? &GTK_CSS_SELECTOR_NOT_PSEUDOCLASS_POSITION
                                                  : &GTK_CSS_SELECTOR_PSEUDOCLASS_POSITION,
                                           selector);
          selector->position.type = POSITION_FORWARD;
          selector->position.a = ab[0];
          selector->position.b = ab[1];
        }
      else if (gtk_css_token_is_function (token, "nth-last-child"))
        {
          gint ab[2];

          if (!gtk_css_parser_consume_function (parser, 1, 1, parse_a_n_plus_b_arg, ab))
            {
              if (selector)
                _gtk_css_selector_free (selector);
              return NULL;
            }

          selector = gtk_css_selector_new (negate ? &GTK_CSS_SELECTOR_NOT_PSEUDOCLASS_POSITION
                                                  : &GTK_CSS_SELECTOR_PSEUDOCLASS_POSITION,
                                           selector);
          selector->position.type = POSITION_BACKWARD;
          selector->position.a = ab[0];
          selector->position.b = ab[1];
        }
      else if (gtk_css_token_is_function (token, "not"))
        {
          if (negate)
            {
              gtk_css_parser_error_syntax (parser, "Nesting of :not() not allowed");
              if (selector)
                _gtk_css_selector_free (selector);
              return NULL;
            }
          else
            {
              gtk_css_parser_start_block (parser);
              token = gtk_css_parser_get_token (parser);

              if (gtk_css_token_is_delim (token, '*'))
                {
                  selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_NOT_ANY, selector);
                  gtk_css_parser_consume_token (parser);
                }
              else if (gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT))
                {
                  selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_NOT_NAME, selector);
                  selector->name.name = g_intern_string (token->string.string);
                  gtk_css_parser_consume_token (parser);
                }
              else if (gtk_css_token_is (token, GTK_CSS_TOKEN_HASH_ID))
                {
                  selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_NOT_ID, selector);
                  selector->id.name = g_intern_string (token->string.string);
                  gtk_css_parser_consume_token (parser);
                }
              else if (gtk_css_token_is_delim (token, '.'))
                {
                  selector = gtk_css_selector_parse_selector_class (parser, selector, TRUE);
                }
              else if (gtk_css_token_is (token, GTK_CSS_TOKEN_COLON))
                {
                  selector = gtk_css_selector_parse_selector_pseudo_class (parser, selector, TRUE);
                }
              else
                {
                  gtk_css_parser_error_syntax (parser, "Invalid contents of :not() selector");
                  gtk_css_parser_end_block (parser);
                  if (selector)
                    _gtk_css_selector_free (selector);
                  selector = NULL;
                  return NULL;
                }

              token = gtk_css_parser_get_token (parser);
              if (!gtk_css_token_is (token, GTK_CSS_TOKEN_EOF))
                {
                  gtk_css_parser_error_syntax (parser, "Invalid contents of :not() selector");
                  gtk_css_parser_end_block (parser);
                  if (selector)
                    _gtk_css_selector_free (selector);
                  selector = NULL;
                  return NULL;
                }
              gtk_css_parser_end_block (parser);
            }
        }
      else if (gtk_css_token_is_function (token, "dir"))
        {
          GtkStateFlags flag;

          if (!gtk_css_parser_consume_function (parser, 1, 1, parse_dir_arg, &flag))
            {
              if (selector)
                _gtk_css_selector_free (selector);
              return NULL;
            }

          selector = gtk_css_selector_new (negate ? &GTK_CSS_SELECTOR_NOT_PSEUDOCLASS_STATE
                                                  : &GTK_CSS_SELECTOR_PSEUDOCLASS_STATE,
                                           selector);
          selector->state.state = flag;
        }
      else if (gtk_css_token_is_function (token, "drop"))
        {
          if (!gtk_css_parser_consume_function (parser, 1, 1, parse_identifier_arg, (gpointer) "active"))
            {
              if (selector)
                _gtk_css_selector_free (selector);
              return NULL;
            }
          selector = gtk_css_selector_new (negate ? &GTK_CSS_SELECTOR_NOT_PSEUDOCLASS_STATE
                                                  : &GTK_CSS_SELECTOR_PSEUDOCLASS_STATE,
                                           selector);
          selector->state.state = GTK_STATE_FLAG_DROP_ACTIVE;
        }
      else if (gtk_css_token_is_function (token, "focus"))
        {
          if (!gtk_css_parser_consume_function (parser, 1, 1, parse_identifier_arg, (gpointer) "visible"))
            {
              if (selector)
                _gtk_css_selector_free (selector);
              return NULL;
            }
          selector = gtk_css_selector_new (negate ? &GTK_CSS_SELECTOR_NOT_PSEUDOCLASS_STATE
                                                  : &GTK_CSS_SELECTOR_PSEUDOCLASS_STATE,
                                           selector);
          selector->state.state = GTK_STATE_FLAG_FOCUS_VISIBLE;
        }
      else
        {
          gtk_css_parser_error (parser,
                                GTK_CSS_PARSER_ERROR_UNKNOWN_VALUE,
                                &start_location,
                                gtk_css_parser_get_end_location (parser),
                                "Unknown pseudoclass");
          if (selector)
            _gtk_css_selector_free (selector);
          return NULL;
        }
    }
  else
    {
      gtk_css_parser_error (parser,
                            GTK_CSS_PARSER_ERROR_UNKNOWN_VALUE,
                            &start_location,
                            gtk_css_parser_get_end_location (parser),
                            "Unknown pseudoclass");
      if (selector)
        _gtk_css_selector_free (selector);
      return NULL;
    }

  return selector;
}

static GtkCssSelector *
gtk_css_selector_parse_simple_selector (GtkCssParser   *parser,
                                        GtkCssSelector *selector)
{
  gboolean parsed_something = FALSE;
  const GtkCssToken *token;

  do {
      for (token = gtk_css_parser_peek_token (parser);
           gtk_css_token_is (token, GTK_CSS_TOKEN_COMMENT);
           token = gtk_css_parser_peek_token (parser))
        {
          gtk_css_parser_consume_token (parser);
        }

      if (!parsed_something && gtk_css_token_is_delim (token, '*'))
        {
          selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_ANY, selector);
          gtk_css_parser_consume_token (parser);
        }
      else if (!parsed_something && gtk_css_token_is (token, GTK_CSS_TOKEN_IDENT))
        {
          selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_NAME, selector);
          selector->name.name = g_intern_string (token->string.string);
          gtk_css_parser_consume_token (parser);
        }
      else if (gtk_css_token_is (token, GTK_CSS_TOKEN_HASH_ID))
        {
          selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_ID, selector);
          selector->id.name = g_intern_string (token->string.string);
          gtk_css_parser_consume_token (parser);
        }
      else if (gtk_css_token_is_delim (token, '.'))
        {
          selector = gtk_css_selector_parse_selector_class (parser, selector, FALSE);
        }
      else if (gtk_css_token_is (token, GTK_CSS_TOKEN_COLON))
        {
          selector = gtk_css_selector_parse_selector_pseudo_class (parser, selector, FALSE);
        }
      else
        {
          if (!parsed_something)
            {
              gtk_css_parser_error_syntax (parser, "Expected a valid selector");
              if (selector)
                _gtk_css_selector_free (selector);
              selector = NULL;
            }
          break;
        }

      parsed_something = TRUE;
    }
  while (TRUE);

  return selector;
}

GtkCssSelector *
_gtk_css_selector_parse (GtkCssParser *parser)
{
  GtkCssSelector *selector = NULL;
  const GtkCssToken *token;

  while (TRUE)
    {
      gboolean seen_whitespace = FALSE;

      /* skip all whitespace and comments */
      gtk_css_parser_get_token (parser);

      selector = gtk_css_selector_parse_simple_selector (parser, selector);
      if (selector == NULL)
        return NULL;

      for (token = gtk_css_parser_peek_token (parser);
           gtk_css_token_is (token, GTK_CSS_TOKEN_COMMENT) || 
           gtk_css_token_is (token, GTK_CSS_TOKEN_WHITESPACE);
           token = gtk_css_parser_peek_token (parser))
        {
          seen_whitespace |= gtk_css_token_is (token, GTK_CSS_TOKEN_WHITESPACE);
          gtk_css_parser_consume_token (parser);
        }

      if (gtk_css_token_is_delim (token, '+'))
        {
          selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_ADJACENT, selector);
          gtk_css_parser_consume_token (parser);
        }
      else if (gtk_css_token_is_delim (token, '~'))
        {
          selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_SIBLING, selector);
          gtk_css_parser_consume_token (parser);
        }
      else if (gtk_css_token_is_delim (token, '>'))
        {
          selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_CHILD, selector);
          gtk_css_parser_consume_token (parser);
        }
      else if (gtk_css_token_is (token, GTK_CSS_TOKEN_EOF) ||
               gtk_css_token_is (token, GTK_CSS_TOKEN_COMMA) ||
               gtk_css_token_is (token, GTK_CSS_TOKEN_OPEN_CURLY))
        {
          break;
        }
      else if (seen_whitespace)
        {
          selector = gtk_css_selector_new (&GTK_CSS_SELECTOR_DESCENDANT, selector);
        }
      else
        {
           gtk_css_parser_error_syntax (parser, "Expected a valid selector");
           _gtk_css_selector_free (selector);
          return NULL;
        }
    }

  return selector;
}

void
_gtk_css_selector_free (GtkCssSelector *selector)
{
  g_return_if_fail (selector != NULL);

  g_free (selector);
}

void
_gtk_css_selector_print (const GtkCssSelector *selector,
                         GString *             str)
{
  const GtkCssSelector *previous;

  g_return_if_fail (selector != NULL);

  previous = gtk_css_selector_previous (selector);
  if (previous)
    _gtk_css_selector_print (previous, str);

  selector->class->print (selector, str);
}

char *
_gtk_css_selector_to_string (const GtkCssSelector *selector)
{
  GString *string;

  g_return_val_if_fail (selector != NULL, NULL);

  string = g_string_new (NULL);

  _gtk_css_selector_print (selector, string);

  return g_string_free (string, FALSE);
}

static gboolean
gtk_css_selector_foreach_match (const GtkCssSelector *selector,
                                const GtkCssMatcher  *matcher,
                                gpointer              unused)
{
  selector = gtk_css_selector_previous (selector);

  if (selector == NULL)
    return TRUE;

  if (!gtk_css_selector_match (selector, matcher))
    return FALSE;

  return gtk_css_selector_foreach (selector, matcher, gtk_css_selector_foreach_match, NULL);
}

/**
 * _gtk_css_selector_matches:
 * @selector: the selector
 * @path: the path to check
 * @state: The state to match
 *
 * Checks if the @selector matches the given @path. If @length is
 * smaller than the number of elements in @path, it is assumed that
 * only the first @length element of @path are valid and the rest
 * does not exist. This is useful for doing parent matches for the
 * 'inherit' keyword.
 *
 * Returns: %TRUE if the selector matches @path
 **/
gboolean
_gtk_css_selector_matches (const GtkCssSelector *selector,
                           const GtkCssMatcher  *matcher)
{

  g_return_val_if_fail (selector != NULL, FALSE);
  g_return_val_if_fail (matcher != NULL, FALSE);

  if (!gtk_css_selector_match (selector, matcher))
    return FALSE;

  return gtk_css_selector_foreach (selector, matcher, gtk_css_selector_foreach_match, NULL);
}

/* Computes specificity according to CSS 2.1.
 * The arguments must be initialized to 0 */
static void
_gtk_css_selector_get_specificity (const GtkCssSelector *selector,
                                   guint                *ids,
                                   guint                *classes,
                                   guint                *elements)
{
  for (; selector; selector = gtk_css_selector_previous (selector))
    {
      selector->class->add_specificity (selector, ids, classes, elements);
    }
}

int
_gtk_css_selector_compare (const GtkCssSelector *a,
                           const GtkCssSelector *b)
{
  guint a_ids = 0, a_classes = 0, a_elements = 0;
  guint b_ids = 0, b_classes = 0, b_elements = 0;
  int compare;

  _gtk_css_selector_get_specificity (a, &a_ids, &a_classes, &a_elements);
  _gtk_css_selector_get_specificity (b, &b_ids, &b_classes, &b_elements);

  compare = a_ids - b_ids;
  if (compare)
    return compare;

  compare = a_classes - b_classes;
  if (compare)
    return compare;

  return a_elements - b_elements;
}

GtkCssChange
_gtk_css_selector_get_change (const GtkCssSelector *selector)
{
  if (selector == NULL)
    return 0;

  return selector->class->get_change (selector, _gtk_css_selector_get_change (gtk_css_selector_previous (selector)));
}

/******************** SelectorTree handling *****************/

static GHashTable *
gtk_css_selectors_count_initial_init (void)
{
  return g_hash_table_new ((GHashFunc)gtk_css_selector_hash_one, (GEqualFunc)gtk_css_selector_equal);
}

static void
gtk_css_selectors_count_initial (const GtkCssSelector *selector, GHashTable *hash_one)
{
  if (!selector->class->is_simple)
    {
      guint count = GPOINTER_TO_INT (g_hash_table_lookup (hash_one, selector));
      g_hash_table_replace (hash_one, (gpointer)selector, GUINT_TO_POINTER (count + 1));
      return;
    }

  for (;
       selector && selector->class->is_simple;
       selector = gtk_css_selector_previous (selector))
    {
      guint count = GPOINTER_TO_INT (g_hash_table_lookup (hash_one, selector));
      g_hash_table_replace (hash_one, (gpointer)selector, GUINT_TO_POINTER (count + 1));
    }
}

static gboolean
gtk_css_selectors_has_initial_selector (const GtkCssSelector *selector, const GtkCssSelector *initial)
{
  if (!selector->class->is_simple)
    return gtk_css_selector_equal (selector, initial);

  for (;
       selector && selector->class->is_simple;
       selector = gtk_css_selector_previous (selector))
    {
      if (gtk_css_selector_equal (selector, initial))
	return TRUE;
    }

  return FALSE;
}

static GtkCssSelector *
gtk_css_selectors_skip_initial_selector (GtkCssSelector *selector, const GtkCssSelector *initial)
{
  GtkCssSelector *found;
  GtkCssSelector tmp;

  /* If the initial simple selector is not first, move it there so we can skip it
     without losing any other selectors */
  if (!gtk_css_selector_equal (selector, initial))
    {
      for (found = selector; found && found->class->is_simple; found = (GtkCssSelector *)gtk_css_selector_previous (found))
	{
	  if (gtk_css_selector_equal (found, initial))
	    break;
	}

      g_assert (found != NULL && found->class->is_simple);

      tmp = *found;
      *found = *selector;
      *selector = tmp;
    }

  return (GtkCssSelector *)gtk_css_selector_previous (selector);
}

static gboolean
gtk_css_selector_tree_match_foreach (const GtkCssSelector *selector,
                                     const GtkCssMatcher  *matcher,
                                     gpointer              res)
{
  const GtkCssSelectorTree *tree = (const GtkCssSelectorTree *) selector;
  const GtkCssSelectorTree *prev;

  if (!gtk_css_selector_match (selector, matcher))
    return FALSE;

  gtk_css_selector_tree_found_match (tree, res);

  for (prev = gtk_css_selector_tree_get_previous (tree);
       prev != NULL;
       prev = gtk_css_selector_tree_get_sibling (prev))
    gtk_css_selector_foreach (&prev->selector, matcher, gtk_css_selector_tree_match_foreach, res);

  return FALSE;
}

GPtrArray *
_gtk_css_selector_tree_match_all (const GtkCssSelectorTree *tree,
				  const GtkCssMatcher *matcher)
{
  GPtrArray *array = NULL;

  for (; tree != NULL;
       tree = gtk_css_selector_tree_get_sibling (tree))
    gtk_css_selector_foreach (&tree->selector, matcher, gtk_css_selector_tree_match_foreach, &array);

  return array;
}

/* When checking for changes via the tree we need to know if a rule further
   down the tree matched, because if so we need to add "our bit" to the
   Change. For instance in a match like *.class:active we'll
   get a tree that first checks :active, if that matches we continue down
   to the tree, and if we get a match we add CHANGE_CLASS. However, the
   end of the tree where we have a match is an ANY which doesn't actually
   modify the change, so we don't know if we have a match or not. We fix
   this by setting GTK_CSS_CHANGE_GOT_MATCH which lets us guarantee
   that change != 0 on any match. */
#define GTK_CSS_CHANGE_GOT_MATCH GTK_CSS_CHANGE_RESERVED_BIT

static GtkCssChange
gtk_css_selector_tree_collect_change (const GtkCssSelectorTree *tree)
{
  GtkCssChange change = 0;
  const GtkCssSelectorTree *prev;

  for (prev = gtk_css_selector_tree_get_previous (tree);
       prev != NULL;
       prev = gtk_css_selector_tree_get_sibling (prev))
    change |= gtk_css_selector_tree_collect_change (prev);

  change = tree->selector.class->get_change (&tree->selector, change);

  return change;
}

static GtkCssChange
gtk_css_selector_tree_get_change (const GtkCssSelectorTree *tree,
				  const GtkCssMatcher      *matcher)
{
  GtkCssChange change = 0;
  const GtkCssSelectorTree *prev;

  if (!gtk_css_selector_match (&tree->selector, matcher))
    return 0;

  if (!tree->selector.class->is_simple)
    return gtk_css_selector_tree_collect_change (tree) | GTK_CSS_CHANGE_GOT_MATCH;

  for (prev = gtk_css_selector_tree_get_previous (tree);
       prev != NULL;
       prev = gtk_css_selector_tree_get_sibling (prev))
    change |= gtk_css_selector_tree_get_change (prev, matcher);

  if (change || gtk_css_selector_tree_get_matches (tree))
    change = tree->selector.class->get_change (&tree->selector, change & ~GTK_CSS_CHANGE_GOT_MATCH) | GTK_CSS_CHANGE_GOT_MATCH;

  return change;
}

gboolean
_gtk_css_selector_tree_is_empty (const GtkCssSelectorTree *tree)
{
  return tree == NULL;
}

GtkCssChange
_gtk_css_selector_tree_get_change_all (const GtkCssSelectorTree *tree,
				       const GtkCssMatcher *matcher)
{
  GtkCssChange change;

  change = 0;

  /* no need to foreach here because we abort for non-simple selectors */
  for (; tree != NULL;
       tree = gtk_css_selector_tree_get_sibling (tree))
    change |= gtk_css_selector_tree_get_change (tree, matcher);

  /* Never return reserved bit set */
  return change & ~GTK_CSS_CHANGE_RESERVED_BIT;
}

#ifdef PRINT_TREE
static void
_gtk_css_selector_tree_print (const GtkCssSelectorTree *tree, GString *str, char *prefix)
{
  gboolean first = TRUE;
  int len, i;

  for (; tree != NULL; tree = gtk_css_selector_tree_get_sibling (tree), first = FALSE)
    {
      if (!first)
	g_string_append (str, prefix);

      if (first)
	{
	  if (gtk_css_selector_tree_get_sibling (tree))
	    g_string_append (str, "─┬─");
	  else
	    g_string_append (str, "───");
	}
      else
	{
	  if (gtk_css_selector_tree_get_sibling (tree))
	    g_string_append (str, " ├─");
	  else
	    g_string_append (str, " └─");
	}

      len = str->len;
      tree->selector.class->print (&tree->selector, str);
      len = str->len - len;

      if (gtk_css_selector_tree_get_previous (tree))
	{
	  GString *prefix2 = g_string_new (prefix);

	  if (gtk_css_selector_tree_get_sibling (tree))
	    g_string_append (prefix2, " │ ");
	  else
	    g_string_append (prefix2, "   ");
	  for (i = 0; i < len; i++)
	    g_string_append_c (prefix2, ' ');

	  _gtk_css_selector_tree_print (gtk_css_selector_tree_get_previous (tree), str, prefix2->str);
	  g_string_free (prefix2, TRUE);
	}
      else
	g_string_append (str, "\n");
    }
}
#endif

void
_gtk_css_selector_tree_match_print (const GtkCssSelectorTree *tree,
				    GString *str)
{
  const GtkCssSelectorTree *iter;

  g_return_if_fail (tree != NULL);

  /* print name and * selector before others */
  for (iter = tree; 
       iter && iter->selector.class->is_simple;
       iter = gtk_css_selector_tree_get_parent (iter))
    {
      if (iter->selector.class == &GTK_CSS_SELECTOR_NAME ||
          iter->selector.class == &GTK_CSS_SELECTOR_ANY)
        {
          iter->selector.class->print (&iter->selector, str);
        }
    }
  /* now print other simple selectors */
  for (iter = tree; 
       iter && iter->selector.class->is_simple;
       iter = gtk_css_selector_tree_get_parent (iter))
    {
      if (iter->selector.class != &GTK_CSS_SELECTOR_NAME &&
          iter->selector.class != &GTK_CSS_SELECTOR_ANY)
        {
          iter->selector.class->print (&iter->selector, str);
        }
    }

  /* now if there's a combinator, print that one */
  if (iter != NULL)
    {
      iter->selector.class->print (&iter->selector, str);
      tree = gtk_css_selector_tree_get_parent (iter);
      if (tree)
        _gtk_css_selector_tree_match_print (tree, str);
    }
}

void
_gtk_css_selector_tree_free (GtkCssSelectorTree *tree)
{
  if (tree == NULL)
    return;

  g_free (tree);
}


typedef struct {
  gpointer match;
  GtkCssSelector *current_selector;
  GtkCssSelectorTree **selector_match;
} GtkCssSelectorRuleSetInfo;

static GtkCssSelectorTree *
get_tree (GByteArray *array, gint32 offset)
{
  return (GtkCssSelectorTree *) (array->data + offset);
}

static GtkCssSelectorTree *
alloc_tree (GByteArray *array, gint32 *offset)
{
  GtkCssSelectorTree tree = { { NULL} };

  *offset = array->len;
  g_byte_array_append (array, (guint8 *)&tree, sizeof (GtkCssSelectorTree));
  return get_tree (array, *offset);
}

static gint32
subdivide_infos (GByteArray *array, GList *infos, gint32 parent_offset)
{
  GHashTable *ht;
  GList *l;
  GList *matched;
  GList *remaining;
  gint32 tree_offset;
  GtkCssSelectorTree *tree;
  GtkCssSelectorRuleSetInfo *info;
  GtkCssSelector max_selector;
  GHashTableIter iter;
  guint max_count;
  gpointer key, value;
  GPtrArray *exact_matches;
  gint32 res;

  if (infos == NULL)
    return GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET;

  ht = gtk_css_selectors_count_initial_init ();

  for (l = infos; l != NULL; l = l->next)
    {
      info = l->data;
      gtk_css_selectors_count_initial (info->current_selector, ht);
    }

  /* Pick the selector with highest count, and use as decision on this level
     as that makes it possible to skip the largest amount of checks later */

  max_count = 0;

  g_hash_table_iter_init (&iter, ht);
  while (g_hash_table_iter_next (&iter, &key, &value))
    {
      GtkCssSelector *selector = key;
      if (GPOINTER_TO_UINT (value) > max_count ||
	  (GPOINTER_TO_UINT (value) == max_count &&
	  gtk_css_selector_compare_one (selector, &max_selector) < 0))
	{
	  max_count = GPOINTER_TO_UINT (value);
	  max_selector = *selector;
	}
    }

  matched = NULL;
  remaining = NULL;

  tree = alloc_tree (array, &tree_offset);
  tree->parent_offset = parent_offset;
  tree->selector = max_selector;

  exact_matches = NULL;
  for (l = infos; l != NULL; l = l->next)
    {
      info = l->data;

      if (gtk_css_selectors_has_initial_selector (info->current_selector, &max_selector))
	{
	  info->current_selector = gtk_css_selectors_skip_initial_selector (info->current_selector, &max_selector);
	  if (info->current_selector == NULL)
	    {
	      /* Matches current node */
	      if (exact_matches == NULL)
		exact_matches = g_ptr_array_new ();
	      g_ptr_array_add (exact_matches, info->match);
	      if (info->selector_match != NULL)
		*info->selector_match = GUINT_TO_POINTER (tree_offset);
	    }
	  else
	    matched = g_list_prepend (matched, info);
	}
      else
	{
	  remaining = g_list_prepend (remaining, info);
	}
    }

  if (exact_matches)
    {
      g_ptr_array_add (exact_matches, NULL); /* Null terminate */
      res = array->len;
      g_byte_array_append (array, (guint8 *)exact_matches->pdata,
			   exact_matches->len * sizeof (gpointer));
      g_ptr_array_free (exact_matches, TRUE);
    }
  else
    res = GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET;
  get_tree (array, tree_offset)->matches_offset = res;

  res = subdivide_infos (array, matched, tree_offset);
  get_tree (array, tree_offset)->previous_offset = res;

  res = subdivide_infos (array, remaining, parent_offset);
  get_tree (array, tree_offset)->sibling_offset = res;

  g_list_free (matched);
  g_list_free (remaining);
  g_hash_table_unref (ht);

  return tree_offset;
}

struct _GtkCssSelectorTreeBuilder {
  GList  *infos;
};

GtkCssSelectorTreeBuilder *
_gtk_css_selector_tree_builder_new (void)
{
  return g_new0 (GtkCssSelectorTreeBuilder, 1);
}

void
_gtk_css_selector_tree_builder_free  (GtkCssSelectorTreeBuilder *builder)
{
  g_list_free_full (builder->infos, g_free);
  g_free (builder);
}

void
_gtk_css_selector_tree_builder_add (GtkCssSelectorTreeBuilder *builder,
				    GtkCssSelector            *selectors,
				    GtkCssSelectorTree       **selector_match,
				    gpointer                   match)
{
  GtkCssSelectorRuleSetInfo *info = g_new0 (GtkCssSelectorRuleSetInfo, 1);

  info->match = match;
  info->current_selector = selectors;
  info->selector_match = selector_match;
  builder->infos = g_list_prepend (builder->infos, info);
}

/* Convert all offsets to node-relative */
static void
fixup_offsets (GtkCssSelectorTree *tree, guint8 *data)
{
  while (tree != NULL)
    {
      if (tree->parent_offset != GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET)
	tree->parent_offset -= ((guint8 *)tree - data);

      if (tree->previous_offset != GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET)
	tree->previous_offset -= ((guint8 *)tree - data);

      if (tree->sibling_offset != GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET)
	tree->sibling_offset -= ((guint8 *)tree - data);

      if (tree->matches_offset != GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET)
	tree->matches_offset -= ((guint8 *)tree - data);

      fixup_offsets ((GtkCssSelectorTree *)gtk_css_selector_tree_get_previous (tree), data);

      tree = (GtkCssSelectorTree *)gtk_css_selector_tree_get_sibling (tree);
    }
}

GtkCssSelectorTree *
_gtk_css_selector_tree_builder_build (GtkCssSelectorTreeBuilder *builder)
{
  GtkCssSelectorTree *tree;
  GByteArray *array;
  guint8 *data;
  guint len;
  GList *l;
  GtkCssSelectorRuleSetInfo *info;

  array = g_byte_array_new ();
  subdivide_infos (array, builder->infos, GTK_CSS_SELECTOR_TREE_EMPTY_OFFSET);

  len = array->len;
  data = g_byte_array_free (array, FALSE);

  /* shrink to final size */
  data = g_realloc (data, len);

  tree = (GtkCssSelectorTree *)data;

  fixup_offsets (tree, data);

  /* Convert offsets to final pointers */
  for (l = builder->infos; l != NULL; l = l->next)
    {
      info = l->data;
      if (info->selector_match)
	*info->selector_match = (GtkCssSelectorTree *)(data + GPOINTER_TO_UINT (*info->selector_match));
    }

#ifdef PRINT_TREE
  {
    GString *s = g_string_new ("");
    _gtk_css_selector_tree_print (tree, s, "");
    g_print ("%s", s->str);
    g_string_free (s, TRUE);
  }
#endif

  return tree;
}