/* GObject - GLib Type, Object, Parameter and Signal Library

 * Copyright (C) 1997-1999, 2000-2001 Tim Janik and 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/>.

 */

/*

 * MT safe

 */

#include "config.h"

#include <string.h>

#include "gparam.h"

#include "gparamspecs.h"

#include "gvaluecollector.h"

#include "gtype-private.h"

/**

 * SECTION:gparamspec

 * @short_description: Metadata for parameter specifications

 * @see_also: g_object_class_install_property(), g_object_set(),

 *     g_object_get(), g_object_set_property(), g_object_get_property(),

 *     g_value_register_transform_func()

 * @title: GParamSpec

 *

 * #GParamSpec is an object structure that encapsulates the metadata

 * required to specify parameters, such as e.g. #GObject properties.

 *

 * ## Parameter names # {#canonical-parameter-names}

 *

 * Parameter names need to start with a letter (a-z or A-Z).

 * Subsequent characters can be letters, numbers or a '-'.

 * All other characters are replaced by a '-' during construction.

 * The result of this replacement is called the canonical name of

 * the parameter.

 */

/* --- defines --- */

#define PARAM_FLOATING_FLAG                     0x2

#define	G_PARAM_USER_MASK			(~0U << G_PARAM_USER_SHIFT)

#define PSPEC_APPLIES_TO_VALUE(pspec, value)	(G_TYPE_CHECK_VALUE_TYPE ((value), G_PARAM_SPEC_VALUE_TYPE (pspec)))

/* --- prototypes --- */

static void	g_param_spec_class_base_init	 (GParamSpecClass	*class);

static void	g_param_spec_class_base_finalize (GParamSpecClass	*class);

static void	g_param_spec_class_init		 (GParamSpecClass	*class,

						  gpointer               class_data);

static void	g_param_spec_init		 (GParamSpec		*pspec,

						  GParamSpecClass	*class);

static void	g_param_spec_finalize		 (GParamSpec		*pspec);

static void	value_param_init		(GValue		*value);

static void	value_param_free_value		(GValue		*value);

static void	value_param_copy_value		(const GValue	*src_value,

						 GValue		*dest_value);

static void	value_param_transform_value	(const GValue	*src_value,

						 GValue		*dest_value);

static gpointer	value_param_peek_pointer	(const GValue	*value);

static gchar*	value_param_collect_value	(GValue		*value,

						 guint           n_collect_values,

						 GTypeCValue    *collect_values,

						 guint           collect_flags);

static gchar*	value_param_lcopy_value		(const GValue	*value,

						 guint           n_collect_values,

						 GTypeCValue    *collect_values,

						 guint           collect_flags);

typedef struct

{

  GValue default_value;

  GQuark name_quark;

} GParamSpecPrivate;

static gint g_param_private_offset;

/* --- functions --- */

static inline GParamSpecPrivate *

g_param_spec_get_private (GParamSpec *pspec)

{

  return &G_STRUCT_MEMBER (GParamSpecPrivate, pspec, g_param_private_offset);

}

void

_g_param_type_init (void)

{

  static const GTypeFundamentalInfo finfo = {

    (G_TYPE_FLAG_CLASSED |

     G_TYPE_FLAG_INSTANTIATABLE |

     G_TYPE_FLAG_DERIVABLE |

     G_TYPE_FLAG_DEEP_DERIVABLE),

  };

  static const GTypeValueTable param_value_table = {

    value_param_init,           /* value_init */

    value_param_free_value,     /* value_free */

    value_param_copy_value,     /* value_copy */

    value_param_peek_pointer,   /* value_peek_pointer */

    "p",			/* collect_format */

    value_param_collect_value,  /* collect_value */

    "p",			/* lcopy_format */

    value_param_lcopy_value,    /* lcopy_value */

  };

  const GTypeInfo param_spec_info = {

    sizeof (GParamSpecClass),

    (GBaseInitFunc) g_param_spec_class_base_init,

    (GBaseFinalizeFunc) g_param_spec_class_base_finalize,

    (GClassInitFunc) g_param_spec_class_init,

    (GClassFinalizeFunc) NULL,

    NULL,	/* class_data */

    sizeof (GParamSpec),

    0,		/* n_preallocs */

    (GInstanceInitFunc) g_param_spec_init,

    &param_value_table,

  };

  GType type;

  /* This should be registered as GParamSpec instead of GParam, for

   * consistency sake, so that type name can be mapped to struct name,

   * However, some language bindings, most noticeable the python ones

   * depends on the "GParam" identifier, see #548689

   */

  type = g_type_register_fundamental (G_TYPE_PARAM, g_intern_static_string ("GParam"), &param_spec_info, &finfo, G_TYPE_FLAG_ABSTRACT);

  g_assert (type == G_TYPE_PARAM);

  g_param_private_offset = g_type_add_instance_private (type, sizeof (GParamSpecPrivate));

  g_value_register_transform_func (G_TYPE_PARAM, G_TYPE_PARAM, value_param_transform_value);

}

static void

g_param_spec_class_base_init (GParamSpecClass *class)

{

}

static void

g_param_spec_class_base_finalize (GParamSpecClass *class)

{

}

static void

g_param_spec_class_init (GParamSpecClass *class,

			 gpointer         class_data)

{

  class->value_type = G_TYPE_NONE;

  class->finalize = g_param_spec_finalize;

  class->value_set_default = NULL;

  class->value_validate = NULL;

  class->values_cmp = NULL;

  g_type_class_adjust_private_offset (class, &g_param_private_offset);

}

static void

g_param_spec_init (GParamSpec      *pspec,

		   GParamSpecClass *class)

{

  pspec->name = NULL;

  pspec->_nick = NULL;

  pspec->_blurb = NULL;

  pspec->flags = 0;

  pspec->value_type = class->value_type;

  pspec->owner_type = 0;

  pspec->qdata = NULL;

  g_datalist_set_flags (&pspec->qdata, PARAM_FLOATING_FLAG);

  pspec->ref_count = 1;

  pspec->param_id = 0;

}

static void

g_param_spec_finalize (GParamSpec *pspec)

{

  GParamSpecPrivate *priv = g_param_spec_get_private (pspec);

  if (priv->default_value.g_type)

    g_value_reset (&priv->default_value);

  g_datalist_clear (&pspec->qdata);

  if (!(pspec->flags & G_PARAM_STATIC_NICK))

    g_free (pspec->_nick);

  if (!(pspec->flags & G_PARAM_STATIC_BLURB))

    g_free (pspec->_blurb);

  g_type_free_instance ((GTypeInstance*) pspec);

}

/**

 * g_param_spec_ref: (skip)

 * @pspec: a valid #GParamSpec

 *

 * Increments the reference count of @pspec.

 *

 * Returns: the #GParamSpec that was passed into this function

 */

GParamSpec*

g_param_spec_ref (GParamSpec *pspec)

{

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), NULL);

  g_atomic_int_inc ((int *)&pspec->ref_count);

  return pspec;

}

/**

 * g_param_spec_unref: (skip)

 * @pspec: a valid #GParamSpec

 *

 * Decrements the reference count of a @pspec.

 */

void

g_param_spec_unref (GParamSpec *pspec)

{

  gboolean is_zero;

  g_return_if_fail (G_IS_PARAM_SPEC (pspec));

  is_zero = g_atomic_int_dec_and_test ((int *)&pspec->ref_count);

  if (G_UNLIKELY (is_zero))

    {

      G_PARAM_SPEC_GET_CLASS (pspec)->finalize (pspec);

    }

}

/**

 * g_param_spec_sink:

 * @pspec: a valid #GParamSpec

 *

 * The initial reference count of a newly created #GParamSpec is 1,

 * even though no one has explicitly called g_param_spec_ref() on it

 * yet. So the initial reference count is flagged as "floating", until

 * someone calls `g_param_spec_ref (pspec); g_param_spec_sink

 * (pspec);` in sequence on it, taking over the initial

 * reference count (thus ending up with a @pspec that has a reference

 * count of 1 still, but is not flagged "floating" anymore).

 */

void

g_param_spec_sink (GParamSpec *pspec)

{

  gsize oldvalue;

  g_return_if_fail (G_IS_PARAM_SPEC (pspec));

  oldvalue = g_atomic_pointer_and (&pspec->qdata, ~(gsize)PARAM_FLOATING_FLAG);

  if (oldvalue & PARAM_FLOATING_FLAG)

    g_param_spec_unref (pspec);

}

/**

 * g_param_spec_ref_sink: (skip)

 * @pspec: a valid #GParamSpec

 *

 * Convenience function to ref and sink a #GParamSpec.

 *

 * Since: 2.10

 * Returns: the #GParamSpec that was passed into this function

 */

GParamSpec*

g_param_spec_ref_sink (GParamSpec *pspec)

{

  gsize oldvalue;

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), NULL);

  oldvalue = g_atomic_pointer_and (&pspec->qdata, ~(gsize)PARAM_FLOATING_FLAG);

  if (!(oldvalue & PARAM_FLOATING_FLAG))

    g_param_spec_ref (pspec);

  return pspec;

}

/**

 * g_param_spec_get_name:

 * @pspec: a valid #GParamSpec

 *

 * Get the name of a #GParamSpec.

 *

 * The name is always an "interned" string (as per g_intern_string()).

 * This allows for pointer-value comparisons.

 *

 * Returns: the name of @pspec.

 */

const gchar *

g_param_spec_get_name (GParamSpec *pspec)

{

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), NULL);

  return pspec->name;

}

/**

 * g_param_spec_get_nick:

 * @pspec: a valid #GParamSpec

 *

 * Get the nickname of a #GParamSpec.

 *

 * Returns: the nickname of @pspec.

 */

const gchar *

g_param_spec_get_nick (GParamSpec *pspec)

{

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), NULL);

  if (pspec->_nick)

    return pspec->_nick;

  else

    {

      GParamSpec *redirect_target;

      redirect_target = g_param_spec_get_redirect_target (pspec);

      if (redirect_target && redirect_target->_nick)

	return redirect_target->_nick;

    }

  return pspec->name;

}

/**

 * g_param_spec_get_blurb:

 * @pspec: a valid #GParamSpec

 *

 * Get the short description of a #GParamSpec.

 *

 * Returns: the short description of @pspec.

 */

const gchar *

g_param_spec_get_blurb (GParamSpec *pspec)

{

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), NULL);

  if (pspec->_blurb)

    return pspec->_blurb;

  else

    {

      GParamSpec *redirect_target;

      redirect_target = g_param_spec_get_redirect_target (pspec);

      if (redirect_target && redirect_target->_blurb)

	return redirect_target->_blurb;

    }

  return NULL;

}

static void

canonicalize_key (gchar *key)

{

  gchar *p;

  for (p = key; *p != 0; p++)

    {

      gchar c = *p;

      if (c != '-' &&

	  (c < '0' || c > '9') &&

	  (c < 'A' || c > 'Z') &&

	  (c < 'a' || c > 'z'))

	*p = '-';

    }

}

static gboolean

is_canonical (const gchar *key)

{

  const gchar *p;

  for (p = key; *p != 0; p++)

    {

      gchar c = *p;

      if (c != '-' &&

	  (c < '0' || c > '9') &&

	  (c < 'A' || c > 'Z') &&

	  (c < 'a' || c > 'z'))

	return FALSE;

    }

  return TRUE;

}

/**

 * g_param_spec_internal: (skip)

 * @param_type: the #GType for the property; must be derived from #G_TYPE_PARAM

 * @name: the canonical name of the property

 * @nick: the nickname of the property

 * @blurb: a short description of the property

 * @flags: a combination of #GParamFlags

 *

 * Creates a new #GParamSpec instance.

 *

 * A property name consists of segments consisting of ASCII letters and

 * digits, separated by either the '-' or '_' character. The first

 * character of a property name must be a letter. Names which violate these

 * rules lead to undefined behaviour.

 *

 * When creating and looking up a #GParamSpec, either separator can be

 * used, but they cannot be mixed. Using '-' is considerably more

 * efficient and in fact required when using property names as detail

 * strings for signals.

 *

 * Beyond the name, #GParamSpecs have two more descriptive

 * strings associated with them, the @nick, which should be suitable

 * for use as a label for the property in a property editor, and the

 * @blurb, which should be a somewhat longer description, suitable for

 * e.g. a tooltip. The @nick and @blurb should ideally be localized.

 *

 * Returns: (type GObject.ParamSpec): a newly allocated #GParamSpec instance

 */

gpointer

g_param_spec_internal (GType        param_type,

		       const gchar *name,

		       const gchar *nick,

		       const gchar *blurb,

		       GParamFlags  flags)

{

  GParamSpec *pspec;

  GParamSpecPrivate *priv;

  g_return_val_if_fail (G_TYPE_IS_PARAM (param_type) && param_type != G_TYPE_PARAM, NULL);

  g_return_val_if_fail (name != NULL, NULL);

  g_return_val_if_fail ((name[0] >= 'A' && name[0] <= 'Z') || (name[0] >= 'a' && name[0] <= 'z'), NULL);

  g_return_val_if_fail (!(flags & G_PARAM_STATIC_NAME) || is_canonical (name), NULL);

  pspec = (gpointer) g_type_create_instance (param_type);

  if (flags & G_PARAM_STATIC_NAME)

    {

      /* pspec->name is not freed if (flags & G_PARAM_STATIC_NAME) */

      pspec->name = (gchar *) g_intern_static_string (name);

      if (!is_canonical (pspec->name))

        g_warning ("G_PARAM_STATIC_NAME used with non-canonical pspec name: %s", pspec->name);

    }

  else

    {

      if (is_canonical (name))

        pspec->name = (gchar *) g_intern_string (name);

      else

        {

          gchar *tmp = g_strdup (name);

          canonicalize_key (tmp);

          pspec->name = (gchar *) g_intern_string (tmp);

          g_free (tmp);

        }

    }

  priv = g_param_spec_get_private (pspec);

  priv->name_quark = g_quark_from_string (pspec->name);

  if (flags & G_PARAM_STATIC_NICK)

    pspec->_nick = (gchar*) nick;

  else

    pspec->_nick = g_strdup (nick);

  if (flags & G_PARAM_STATIC_BLURB)

    pspec->_blurb = (gchar*) blurb;

  else

    pspec->_blurb = g_strdup (blurb);

  pspec->flags = (flags & G_PARAM_USER_MASK) | (flags & G_PARAM_MASK);

  return pspec;

}

/**

 * g_param_spec_get_qdata:

 * @pspec: a valid #GParamSpec

 * @quark: a #GQuark, naming the user data pointer

 *

 * Gets back user data pointers stored via g_param_spec_set_qdata().

 *

 * Returns: (transfer none): the user data pointer set, or %NULL

 */

gpointer

g_param_spec_get_qdata (GParamSpec *pspec,

			GQuark      quark)

{

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), NULL);

  return quark ? g_datalist_id_get_data (&pspec->qdata, quark) : NULL;

}

/**

 * g_param_spec_set_qdata:

 * @pspec: the #GParamSpec to set store a user data pointer

 * @quark: a #GQuark, naming the user data pointer

 * @data: an opaque user data pointer

 *

 * Sets an opaque, named pointer on a #GParamSpec. The name is

 * specified through a #GQuark (retrieved e.g. via

 * g_quark_from_static_string()), and the pointer can be gotten back

 * from the @pspec with g_param_spec_get_qdata().  Setting a

 * previously set user data pointer, overrides (frees) the old pointer

 * set, using %NULL as pointer essentially removes the data stored.

 */

void

g_param_spec_set_qdata (GParamSpec *pspec,

			GQuark      quark,

			gpointer    data)

{

  g_return_if_fail (G_IS_PARAM_SPEC (pspec));

  g_return_if_fail (quark > 0);

  g_datalist_id_set_data (&pspec->qdata, quark, data);

}

/**

 * g_param_spec_set_qdata_full: (skip)

 * @pspec: the #GParamSpec to set store a user data pointer

 * @quark: a #GQuark, naming the user data pointer

 * @data: an opaque user data pointer

 * @destroy: function to invoke with @data as argument, when @data needs to

 *  be freed

 *

 * This function works like g_param_spec_set_qdata(), but in addition,

 * a `void (*destroy) (gpointer)` function may be

 * specified which is called with @data as argument when the @pspec is

 * finalized, or the data is being overwritten by a call to

 * g_param_spec_set_qdata() with the same @quark.

 */

void

g_param_spec_set_qdata_full (GParamSpec    *pspec,

			     GQuark         quark,

			     gpointer       data,

			     GDestroyNotify destroy)

{

  g_return_if_fail (G_IS_PARAM_SPEC (pspec));

  g_return_if_fail (quark > 0);

  g_datalist_id_set_data_full (&pspec->qdata, quark, data, data ? destroy : (GDestroyNotify) NULL);

}

/**

 * g_param_spec_steal_qdata:

 * @pspec: the #GParamSpec to get a stored user data pointer from

 * @quark: a #GQuark, naming the user data pointer

 *

 * Gets back user data pointers stored via g_param_spec_set_qdata()

 * and removes the @data from @pspec without invoking its destroy()

 * function (if any was set).  Usually, calling this function is only

 * required to update user data pointers with a destroy notifier.

 *

 * Returns: (transfer none): the user data pointer set, or %NULL

 */

gpointer

g_param_spec_steal_qdata (GParamSpec *pspec,

			  GQuark      quark)

{

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), NULL);

  g_return_val_if_fail (quark > 0, NULL);

  return g_datalist_id_remove_no_notify (&pspec->qdata, quark);

}

/**

 * g_param_spec_get_redirect_target:

 * @pspec: a #GParamSpec

 *

 * If the paramspec redirects operations to another paramspec,

 * returns that paramspec. Redirect is used typically for

 * providing a new implementation of a property in a derived

 * type while preserving all the properties from the parent

 * type. Redirection is established by creating a property

 * of type #GParamSpecOverride. See g_object_class_override_property()

 * for an example of the use of this capability.

 *

 * Since: 2.4

 *

 * Returns: (transfer none): paramspec to which requests on this

 *          paramspec should be redirected, or %NULL if none.

 */

GParamSpec*

g_param_spec_get_redirect_target (GParamSpec *pspec)

{

  GTypeInstance *inst = (GTypeInstance *)pspec;

  if (inst && inst->g_class && inst->g_class->g_type == G_TYPE_PARAM_OVERRIDE)

    return ((GParamSpecOverride*)pspec)->overridden;

  else

    return NULL;

}

/**

 * g_param_value_set_default:

 * @pspec: a valid #GParamSpec

 * @value: a #GValue of correct type for @pspec

 *

 * Sets @value to its default value as specified in @pspec.

 */

void

g_param_value_set_default (GParamSpec *pspec,

			   GValue     *value)

{

  g_return_if_fail (G_IS_PARAM_SPEC (pspec));

  g_return_if_fail (G_IS_VALUE (value));

  g_return_if_fail (PSPEC_APPLIES_TO_VALUE (pspec, value));

  g_value_reset (value);

  G_PARAM_SPEC_GET_CLASS (pspec)->value_set_default (pspec, value);

}

/**

 * g_param_value_defaults:

 * @pspec: a valid #GParamSpec

 * @value: a #GValue of correct type for @pspec

 *

 * Checks whether @value contains the default value as specified in @pspec.

 *

 * Returns: whether @value contains the canonical default for this @pspec

 */

gboolean

g_param_value_defaults (GParamSpec *pspec,

			GValue     *value)

{

  GValue dflt_value = G_VALUE_INIT;

  gboolean defaults;

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), FALSE);

  g_return_val_if_fail (G_IS_VALUE (value), FALSE);

  g_return_val_if_fail (PSPEC_APPLIES_TO_VALUE (pspec, value), FALSE);

  g_value_init (&dflt_value, G_PARAM_SPEC_VALUE_TYPE (pspec));

  G_PARAM_SPEC_GET_CLASS (pspec)->value_set_default (pspec, &dflt_value);

  defaults = G_PARAM_SPEC_GET_CLASS (pspec)->values_cmp (pspec, value, &dflt_value) == 0;

  g_value_unset (&dflt_value);

  return defaults;

}

/**

 * g_param_value_validate:

 * @pspec: a valid #GParamSpec

 * @value: a #GValue of correct type for @pspec

 *

 * Ensures that the contents of @value comply with the specifications

 * set out by @pspec. For example, a #GParamSpecInt might require

 * that integers stored in @value may not be smaller than -42 and not be

 * greater than +42. If @value contains an integer outside of this range,

 * it is modified accordingly, so the resulting value will fit into the

 * range -42 .. +42.

 *

 * Returns: whether modifying @value was necessary to ensure validity

 */

gboolean

g_param_value_validate (GParamSpec *pspec,

			GValue     *value)

{

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), FALSE);

  g_return_val_if_fail (G_IS_VALUE (value), FALSE);

  g_return_val_if_fail (PSPEC_APPLIES_TO_VALUE (pspec, value), FALSE);

  if (G_PARAM_SPEC_GET_CLASS (pspec)->value_validate)

    {

      GValue oval = *value;

      if (G_PARAM_SPEC_GET_CLASS (pspec)->value_validate (pspec, value) ||

	  memcmp (&oval.data, &value->data, sizeof (oval.data)))

	return TRUE;

    }

  return FALSE;

}

/**

 * g_param_value_convert:

 * @pspec: a valid #GParamSpec

 * @src_value: souce #GValue

 * @dest_value: destination #GValue of correct type for @pspec

 * @strict_validation: %TRUE requires @dest_value to conform to @pspec

 * without modifications

 *

 * Transforms @src_value into @dest_value if possible, and then

 * validates @dest_value, in order for it to conform to @pspec.  If

 * @strict_validation is %TRUE this function will only succeed if the

 * transformed @dest_value complied to @pspec without modifications.

 *

 * See also g_value_type_transformable(), g_value_transform() and

 * g_param_value_validate().

 *

 * Returns: %TRUE if transformation and validation were successful,

 *  %FALSE otherwise and @dest_value is left untouched.

 */

gboolean

g_param_value_convert (GParamSpec   *pspec,

		       const GValue *src_value,

		       GValue       *dest_value,

		       gboolean	     strict_validation)

{

  GValue tmp_value = G_VALUE_INIT;

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), FALSE);

  g_return_val_if_fail (G_IS_VALUE (src_value), FALSE);

  g_return_val_if_fail (G_IS_VALUE (dest_value), FALSE);

  g_return_val_if_fail (PSPEC_APPLIES_TO_VALUE (pspec, dest_value), FALSE);

  /* better leave dest_value untouched when returning FALSE */

  g_value_init (&tmp_value, G_VALUE_TYPE (dest_value));

  if (g_value_transform (src_value, &tmp_value) &&

      (!g_param_value_validate (pspec, &tmp_value) || !strict_validation))

    {

      g_value_unset (dest_value);

      /* values are relocatable */

      memcpy (dest_value, &tmp_value, sizeof (tmp_value));

      return TRUE;

    }

  else

    {

      g_value_unset (&tmp_value);

      return FALSE;

    }

}

/**

 * g_param_values_cmp:

 * @pspec: a valid #GParamSpec

 * @value1: a #GValue of correct type for @pspec

 * @value2: a #GValue of correct type for @pspec

 *

 * Compares @value1 with @value2 according to @pspec, and return -1, 0 or +1,

 * if @value1 is found to be less than, equal to or greater than @value2,

 * respectively.

 *

 * Returns: -1, 0 or +1, for a less than, equal to or greater than result

 */

gint

g_param_values_cmp (GParamSpec   *pspec,

		    const GValue *value1,

		    const GValue *value2)

{

  gint cmp;

  /* param_values_cmp() effectively does: value1 - value2

   * so the return values are:

   * -1)  value1 < value2

   *  0)  value1 == value2

   *  1)  value1 > value2

   */

  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), 0);

  g_return_val_if_fail (G_IS_VALUE (value1), 0);

  g_return_val_if_fail (G_IS_VALUE (value2), 0);

  g_return_val_if_fail (PSPEC_APPLIES_TO_VALUE (pspec, value1), 0);

  g_return_val_if_fail (PSPEC_APPLIES_TO_VALUE (pspec, value2), 0);

  cmp = G_PARAM_SPEC_GET_CLASS (pspec)->values_cmp (pspec, value1, value2);

  return CLAMP (cmp, -1, 1);

}

static void

value_param_init (GValue *value)

{

  value->data[0].v_pointer = NULL;

}

static void

value_param_free_value (GValue *value)

{

  if (value->data[0].v_pointer)

    g_param_spec_unref (value->data[0].v_pointer);

}

static void

value_param_copy_value (const GValue *src_value,

			GValue       *dest_value)

{

  if (src_value->data[0].v_pointer)

    dest_value->data[0].v_pointer = g_param_spec_ref (src_value->data[0].v_pointer);

  else

    dest_value->data[0].v_pointer = NULL;

}

static void

value_param_transform_value (const GValue *src_value,

			     GValue       *dest_value)

{

  if (src_value->data[0].v_pointer &&

      g_type_is_a (G_PARAM_SPEC_TYPE (dest_value->data[0].v_pointer), G_VALUE_TYPE (dest_value)))

    dest_value->data[0].v_pointer = g_param_spec_ref (src_value->data[0].v_pointer);

  else

    dest_value->data[0].v_pointer = NULL;

}

static gpointer

value_param_peek_pointer (const GValue *value)

{

  return value->data[0].v_pointer;

}

static gchar*

value_param_collect_value (GValue      *value,

			   guint        n_collect_values,

			   GTypeCValue *collect_values,

			   guint        collect_flags)

{

  if (collect_values[0].v_pointer)

    {

      GParamSpec *param = collect_values[0].v_pointer;

      if (param->g_type_instance.g_class == NULL)

	return g_strconcat ("invalid unclassed param spec pointer for value type '",

			    G_VALUE_TYPE_NAME (value),

			    "'",

			    NULL);

      else if (!g_value_type_compatible (G_PARAM_SPEC_TYPE (param), G_VALUE_TYPE (value)))

	return g_strconcat ("invalid param spec type '",

			    G_PARAM_SPEC_TYPE_NAME (param),

			    "' for value type '",

			    G_VALUE_TYPE_NAME (value),

			    "'",

			    NULL);

      value->data[0].v_pointer = g_param_spec_ref (param);

    }

  else

    value->data[0].v_pointer = NULL;

  return NULL;

}

static gchar*

value_param_lcopy_value (const GValue *value,

			 guint         n_collect_values,

			 GTypeCValue  *collect_values,

			 guint         collect_flags)

{

  GParamSpec **param_p = collect_values[0].v_pointer;

  if (!param_p)

    return g_strdup_printf ("value location for '%s' passed as NULL", G_VALUE_TYPE_NAME (value));

  if (!value->data[0].v_pointer)

    *param_p = NULL;

  else if (collect_flags & G_VALUE_NOCOPY_CONTENTS)

    *param_p = value->data[0].v_pointer;

  else

    *param_p = g_param_spec_ref (value->data[0].v_pointer);

  return NULL;

}

/* --- param spec pool --- */

/**

 * GParamSpecPool:

 *

 * A #GParamSpecPool maintains a collection of #GParamSpecs which can be

 * quickly accessed by owner and name. The implementation of the #GObject property

 * system uses such a pool to store the #GParamSpecs of the properties all object

 * types.

 */

struct _GParamSpecPool

{

  GMutex       mutex;

  gboolean     type_prefixing;

  GHashTable  *hash_table;

};

static guint

param_spec_pool_hash (gconstpointer key_spec)

{

  const GParamSpec *key = key_spec;

  const gchar *p;

  guint h = key->owner_type;

  for (p = key->name; *p; p++)