/* GStreamer

 * Copyright (C) 2003 David A. Schleef <ds@schleef.org>

 *

 * gststructure.c: lists of { GQuark, GValue } tuples

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library 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

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

/**

 * SECTION:gststructure

 * @title: GstStructure

 * @short_description: Generic structure containing fields of names and values

 * @see_also: #GstCaps, #GstMessage, #GstEvent, #GstQuery

 *

 * A #GstStructure is a collection of key/value pairs. The keys are expressed

 * as GQuarks and the values can be of any GType.

 *

 * In addition to the key/value pairs, a #GstStructure also has a name. The name

 * starts with a letter and can be filled by letters, numbers and any of "/-_.:".

 *

 * #GstStructure is used by various GStreamer subsystems to store information

 * in a flexible and extensible way. A #GstStructure does not have a refcount

 * because it usually is part of a higher level object such as #GstCaps,

 * #GstMessage, #GstEvent, #GstQuery. It provides a means to enforce mutability

 * using the refcount of the parent with the gst_structure_set_parent_refcount()

 * method.

 *

 * A #GstStructure can be created with gst_structure_new_empty() or

 * gst_structure_new(), which both take a name and an optional set of

 * key/value pairs along with the types of the values.

 *

 * Field values can be changed with gst_structure_set_value() or

 * gst_structure_set().

 *

 * Field values can be retrieved with gst_structure_get_value() or the more

 * convenient gst_structure_get_*() functions.

 *

 * Fields can be removed with gst_structure_remove_field() or

 * gst_structure_remove_fields().

 *

 * Strings in structures must be ASCII or UTF-8 encoded. Other encodings are

 * not allowed. Strings may be %NULL however.

 *

 * Be aware that the current #GstCaps / #GstStructure serialization into string

 * has limited support for nested #GstCaps / #GstStructure fields. It can only

 * support one level of nesting. Using more levels will lead to unexpected

 * behavior when using serialization features, such as gst_caps_to_string() or

 * gst_value_serialize() and their counterparts.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

/* FIXME 2.0: suppress warnings for deprecated API such as GValueArray

 * with newer GLib versions (>= 2.31.0) */

#define GLIB_DISABLE_DEPRECATION_WARNINGS

#include <string.h>

#include "gst_private.h"

#include "gstquark.h"

#include <gst/gst.h>

#include <gobject/gvaluecollector.h>

GST_DEBUG_CATEGORY_STATIC (gst_structure_debug);

#define GST_CAT_DEFAULT gst_structure_debug

typedef struct _GstStructureField GstStructureField;

struct _GstStructureField

{

  GQuark name;

  GValue value;

};

typedef struct

{

  GstStructure s;

  /* owned by parent structure, NULL if no parent */

  gint *parent_refcount;

  GArray *fields;

} GstStructureImpl;

#define GST_STRUCTURE_REFCOUNT(s) (((GstStructureImpl*)(s))->parent_refcount)

#define GST_STRUCTURE_FIELDS(s) (((GstStructureImpl*)(s))->fields)

#define GST_STRUCTURE_FIELD(structure, index) \

    &g_array_index(GST_STRUCTURE_FIELDS(structure), GstStructureField, (index))

#define IS_MUTABLE(structure) \

    (!GST_STRUCTURE_REFCOUNT(structure) || \

     g_atomic_int_get (GST_STRUCTURE_REFCOUNT(structure)) == 1)

#define IS_TAGLIST(structure) \

    (structure->name == GST_QUARK (TAGLIST))

static void gst_structure_set_field (GstStructure * structure,

    GstStructureField * field);

static GstStructureField *gst_structure_get_field (const GstStructure *

    structure, const gchar * fieldname);

static GstStructureField *gst_structure_id_get_field (const GstStructure *

    structure, GQuark field);

static void gst_structure_transform_to_string (const GValue * src_value,

    GValue * dest_value);

static GstStructure *gst_structure_copy_conditional (const GstStructure *

    structure);

GType _gst_structure_type = 0;

G_DEFINE_BOXED_TYPE (GstStructure, gst_structure,

    gst_structure_copy_conditional, gst_structure_free);

void

_priv_gst_structure_initialize (void)

{

  _gst_structure_type = gst_structure_get_type ();

  g_value_register_transform_func (_gst_structure_type, G_TYPE_STRING,

      gst_structure_transform_to_string);

  GST_DEBUG_CATEGORY_INIT (gst_structure_debug, "structure", 0,

      "GstStructure debug");

}

static GstStructure *

gst_structure_new_id_empty_with_size (GQuark quark, guint prealloc)

{

  GstStructureImpl *structure;

  structure = g_slice_new (GstStructureImpl);

  ((GstStructure *) structure)->type = _gst_structure_type;

  ((GstStructure *) structure)->name = quark;

  GST_STRUCTURE_REFCOUNT (structure) = NULL;

  GST_STRUCTURE_FIELDS (structure) =

      g_array_sized_new (FALSE, FALSE, sizeof (GstStructureField), prealloc);

  GST_TRACE ("created structure %p", structure);

  return GST_STRUCTURE_CAST (structure);

}

/**

 * gst_structure_new_id_empty:

 * @quark: name of new structure

 *

 * Creates a new, empty #GstStructure with the given name as a GQuark.

 *

 * Free-function: gst_structure_free

 *

 * Returns: (transfer full): a new, empty #GstStructure

 */

GstStructure *

gst_structure_new_id_empty (GQuark quark)

{

  g_return_val_if_fail (quark != 0, NULL);

  return gst_structure_new_id_empty_with_size (quark, 0);

}

#ifndef G_DISABLE_CHECKS

static gboolean

gst_structure_validate_name (const gchar * name)

{

  const gchar *s;

  g_return_val_if_fail (name != NULL, FALSE);

  if (G_UNLIKELY (!g_ascii_isalpha (*name))) {

    GST_WARNING ("Invalid character '%c' at offset 0 in structure name: %s",

        *name, name);

    return FALSE;

  }

  /* FIXME: test name string more */

  s = &name[1];

  while (*s && (g_ascii_isalnum (*s) || strchr ("/-_.:+", *s) != NULL))

    s++;

  if (G_UNLIKELY (*s != '\0')) {

    GST_WARNING ("Invalid character '%c' at offset %" G_GUINTPTR_FORMAT " in"

        " structure name: %s", *s, ((guintptr) s - (guintptr) name), name);

    return FALSE;

  }

  if (strncmp (name, "video/x-raw-", 12) == 0) {

    g_warning ("0.10-style raw video caps are being created. Should be "

        "video/x-raw,format=(string).. now.");

  } else if (strncmp (name, "audio/x-raw-", 12) == 0) {

    g_warning ("0.10-style raw audio caps are being created. Should be "

        "audio/x-raw,format=(string).. now.");

  }

  return TRUE;

}

#endif

/**

 * gst_structure_new_empty:

 * @name: name of new structure

 *

 * Creates a new, empty #GstStructure with the given @name.

 *

 * See gst_structure_set_name() for constraints on the @name parameter.

 *

 * Free-function: gst_structure_free

 *

 * Returns: (transfer full): a new, empty #GstStructure

 */

GstStructure *

gst_structure_new_empty (const gchar * name)

{

  g_return_val_if_fail (gst_structure_validate_name (name), NULL);

  return gst_structure_new_id_empty_with_size (g_quark_from_string (name), 0);

}

/**

 * gst_structure_new:

 * @name: name of new structure

 * @firstfield: name of first field to set

 * @...: additional arguments

 *

 * Creates a new #GstStructure with the given name.  Parses the

 * list of variable arguments and sets fields to the values listed.

 * Variable arguments should be passed as field name, field type,

 * and value.  Last variable argument should be %NULL.

 *

 * Free-function: gst_structure_free

 *

 * Returns: (transfer full): a new #GstStructure

 */

GstStructure *

gst_structure_new (const gchar * name, const gchar * firstfield, ...)

{

  GstStructure *structure;

  va_list varargs;

  va_start (varargs, firstfield);

  structure = gst_structure_new_valist (name, firstfield, varargs);

  va_end (varargs);

  return structure;

}

/**

 * gst_structure_new_valist:

 * @name: name of new structure

 * @firstfield: name of first field to set

 * @varargs: variable argument list

 *

 * Creates a new #GstStructure with the given @name.  Structure fields

 * are set according to the varargs in a manner similar to

 * gst_structure_new().

 *

 * See gst_structure_set_name() for constraints on the @name parameter.

 *

 * Free-function: gst_structure_free

 *

 * Returns: (transfer full): a new #GstStructure

 */

GstStructure *

gst_structure_new_valist (const gchar * name,

    const gchar * firstfield, va_list varargs)

{

  GstStructure *structure;

  structure = gst_structure_new_empty (name);

  if (structure)

    gst_structure_set_valist (structure, firstfield, varargs);

  return structure;

}

/**

 * gst_structure_set_parent_refcount:

 * @structure: a #GstStructure

 * @refcount: (in): a pointer to the parent's refcount

 *

 * Sets the parent_refcount field of #GstStructure. This field is used to

 * determine whether a structure is mutable or not. This function should only be

 * called by code implementing parent objects of #GstStructure, as described in

 * the MT Refcounting section of the design documents.

 *

 * Returns: %TRUE if the parent refcount could be set.

 */

gboolean

gst_structure_set_parent_refcount (GstStructure * structure, gint * refcount)

{

  g_return_val_if_fail (structure != NULL, FALSE);

  /* if we have a parent_refcount already, we can only clear

   * if with a NULL refcount */

  if (GST_STRUCTURE_REFCOUNT (structure)) {

    if (refcount != NULL) {

      g_return_val_if_fail (refcount == NULL, FALSE);

      return FALSE;

    }

  } else {

    if (refcount == NULL) {

      g_return_val_if_fail (refcount != NULL, FALSE);

      return FALSE;

    }

  }

  GST_STRUCTURE_REFCOUNT (structure) = refcount;

  return TRUE;

}

/**

 * gst_structure_copy:

 * @structure: a #GstStructure to duplicate

 *

 * Duplicates a #GstStructure and all its fields and values.

 *

 * Free-function: gst_structure_free

 *

 * Returns: (transfer full): a new #GstStructure.

 */

GstStructure *

gst_structure_copy (const GstStructure * structure)

{

  GstStructure *new_structure;

  GstStructureField *field;

  guint i, len;

  g_return_val_if_fail (structure != NULL, NULL);

  len = GST_STRUCTURE_FIELDS (structure)->len;

  new_structure = gst_structure_new_id_empty_with_size (structure->name, len);

  for (i = 0; i < len; i++) {

    GstStructureField new_field = { 0 };

    field = GST_STRUCTURE_FIELD (structure, i);

    new_field.name = field->name;

    gst_value_init_and_copy (&new_field.value, &field->value);

    g_array_append_val (GST_STRUCTURE_FIELDS (new_structure), new_field);

  }

  GST_CAT_TRACE (GST_CAT_PERFORMANCE, "doing copy %p -> %p",

      structure, new_structure);

  return new_structure;

}

/**

 * gst_structure_free:

 * @structure: (in) (transfer full): the #GstStructure to free

 *

 * Frees a #GstStructure and all its fields and values. The structure must not

 * have a parent when this function is called.

 */

void

gst_structure_free (GstStructure * structure)

{

  GstStructureField *field;

  guint i, len;

  g_return_if_fail (structure != NULL);

  g_return_if_fail (GST_STRUCTURE_REFCOUNT (structure) == NULL);

  len = GST_STRUCTURE_FIELDS (structure)->len;

  for (i = 0; i < len; i++) {

    field = GST_STRUCTURE_FIELD (structure, i);

    if (G_IS_VALUE (&field->value)) {

      g_value_unset (&field->value);

    }

  }

  g_array_free (GST_STRUCTURE_FIELDS (structure), TRUE);

#ifdef USE_POISONING

  memset (structure, 0xff, sizeof (GstStructure));

#endif

  GST_TRACE ("free structure %p", structure);

  g_slice_free1 (sizeof (GstStructureImpl), structure);

}

/**

 * gst_structure_get_name:

 * @structure: a #GstStructure

 *

 * Get the name of @structure as a string.

 *

 * Returns: the name of the structure.

 */

const gchar *

gst_structure_get_name (const GstStructure * structure)

{

  g_return_val_if_fail (structure != NULL, NULL);

  return g_quark_to_string (structure->name);

}

/**

 * gst_structure_has_name:

 * @structure: a #GstStructure

 * @name: structure name to check for

 *

 * Checks if the structure has the given name

 *

 * Returns: %TRUE if @name matches the name of the structure.

 */

gboolean

gst_structure_has_name (const GstStructure * structure, const gchar * name)

{

  const gchar *structure_name;

  g_return_val_if_fail (structure != NULL, FALSE);

  g_return_val_if_fail (name != NULL, FALSE);

  /* getting the string is cheap and comparing short strings is too

   * should be faster than getting the quark for name and comparing the quarks

   */

  structure_name = g_quark_to_string (structure->name);

  return (structure_name && strcmp (structure_name, name) == 0);

}

/**

 * gst_structure_get_name_id:

 * @structure: a #GstStructure

 *

 * Get the name of @structure as a GQuark.

 *

 * Returns: the quark representing the name of the structure.

 */

GQuark

gst_structure_get_name_id (const GstStructure * structure)

{

  g_return_val_if_fail (structure != NULL, 0);

  return structure->name;

}

/**

 * gst_structure_set_name:

 * @structure: a #GstStructure

 * @name: the new name of the structure

 *

 * Sets the name of the structure to the given @name.  The string

 * provided is copied before being used. It must not be empty, start with a

 * letter and can be followed by letters, numbers and any of "/-_.:".

 */

void

gst_structure_set_name (GstStructure * structure, const gchar * name)

{

  g_return_if_fail (structure != NULL);

  g_return_if_fail (IS_MUTABLE (structure));

  g_return_if_fail (gst_structure_validate_name (name));

  structure->name = g_quark_from_string (name);

}

static inline void

gst_structure_id_set_value_internal (GstStructure * structure, GQuark field,

    const GValue * value)

{

  GstStructureField gsfield = { 0, {0,} };

  gsfield.name = field;

  gst_value_init_and_copy (&gsfield.value, value);

  gst_structure_set_field (structure, &gsfield);

}

/**

 * gst_structure_id_set_value:

 * @structure: a #GstStructure

 * @field: a #GQuark representing a field

 * @value: the new value of the field

 *

 * Sets the field with the given GQuark @field to @value.  If the field

 * does not exist, it is created.  If the field exists, the previous

 * value is replaced and freed.

 */

void

gst_structure_id_set_value (GstStructure * structure,

    GQuark field, const GValue * value)

{

  g_return_if_fail (structure != NULL);

  g_return_if_fail (G_IS_VALUE (value));

  g_return_if_fail (IS_MUTABLE (structure));

  gst_structure_id_set_value_internal (structure, field, value);

}

/**

 * gst_structure_set_value:

 * @structure: a #GstStructure

 * @fieldname: the name of the field to set

 * @value: the new value of the field

 *

 * Sets the field with the given name @field to @value.  If the field

 * does not exist, it is created.  If the field exists, the previous

 * value is replaced and freed.

 */

void

gst_structure_set_value (GstStructure * structure,

    const gchar * fieldname, const GValue * value)

{

  g_return_if_fail (structure != NULL);

  g_return_if_fail (fieldname != NULL);

  g_return_if_fail (G_IS_VALUE (value));

  g_return_if_fail (IS_MUTABLE (structure));

  gst_structure_id_set_value_internal (structure,

      g_quark_from_string (fieldname), value);

}

static inline void

gst_structure_id_take_value_internal (GstStructure * structure, GQuark field,

    GValue * value)

{

  GstStructureField gsfield = { 0, {0,} };

  gsfield.name = field;

  gsfield.value = *value;

  gst_structure_set_field (structure, &gsfield);

  /* we took ownership */

#ifdef USE_POISONING

  memset (value, 0, sizeof (GValue));

#else

  value->g_type = G_TYPE_INVALID;

#endif

}

/**

 * gst_structure_id_take_value:

 * @structure: a #GstStructure

 * @field: a #GQuark representing a field

 * @value: (transfer full): the new value of the field

 *

 * Sets the field with the given GQuark @field to @value.  If the field

 * does not exist, it is created.  If the field exists, the previous

 * value is replaced and freed.

 */

void

gst_structure_id_take_value (GstStructure * structure, GQuark field,

    GValue * value)

{

  g_return_if_fail (structure != NULL);

  g_return_if_fail (G_IS_VALUE (value));

  g_return_if_fail (IS_MUTABLE (structure));

  gst_structure_id_take_value_internal (structure, field, value);

}

/**

 * gst_structure_take_value:

 * @structure: a #GstStructure

 * @fieldname: the name of the field to set

 * @value: (transfer full): the new value of the field

 *

 * Sets the field with the given name @field to @value.  If the field

 * does not exist, it is created.  If the field exists, the previous

 * value is replaced and freed. The function will take ownership of @value.

 */

void

gst_structure_take_value (GstStructure * structure, const gchar * fieldname,

    GValue * value)

{

  g_return_if_fail (structure != NULL);

  g_return_if_fail (fieldname != NULL);

  g_return_if_fail (G_IS_VALUE (value));

  g_return_if_fail (IS_MUTABLE (structure));

  gst_structure_id_take_value_internal (structure,

      g_quark_from_string (fieldname), value);

}

static void

gst_structure_set_valist_internal (GstStructure * structure,

    const gchar * fieldname, va_list varargs)

{

  gchar *err = NULL;

  GType type;

  while (fieldname) {

    GstStructureField field = { 0 };

    field.name = g_quark_from_string (fieldname);

    type = va_arg (varargs, GType);

    G_VALUE_COLLECT_INIT (&field.value, type, varargs, 0, &err;;

    if (G_UNLIKELY (err)) {

      g_critical ("%s", err);

      return;

    }

    gst_structure_set_field (structure, &field);

    fieldname = va_arg (varargs, gchar *);

  }

}

/**

 * gst_structure_set:

 * @structure: a #GstStructure

 * @fieldname: the name of the field to set

 * @...: variable arguments

 *

 * Parses the variable arguments and sets fields accordingly. Fields that

 * weren't already part of the structure are added as needed.

 * Variable arguments should be in the form field name, field type

 * (as a GType), value(s).  The last variable argument should be %NULL.

 */

void

gst_structure_set (GstStructure * structure, const gchar * field, ...)

{

  va_list varargs;

  g_return_if_fail (structure != NULL);

  g_return_if_fail (IS_MUTABLE (structure) || field == NULL);

  va_start (varargs, field);

  gst_structure_set_valist_internal (structure, field, varargs);

  va_end (varargs);

}

/**

 * gst_structure_set_valist:

 * @structure: a #GstStructure

 * @fieldname: the name of the field to set

 * @varargs: variable arguments

 *

 * va_list form of gst_structure_set().

 */

void

gst_structure_set_valist (GstStructure * structure,

    const gchar * fieldname, va_list varargs)

{

  g_return_if_fail (structure != NULL);

  g_return_if_fail (IS_MUTABLE (structure));

  gst_structure_set_valist_internal (structure, fieldname, varargs);

}

static void

gst_structure_id_set_valist_internal (GstStructure * structure,

    GQuark fieldname, va_list varargs)

{

  gchar *err = NULL;

  GType type;

  while (fieldname) {

    GstStructureField field = { 0 };

    field.name = fieldname;

    type = va_arg (varargs, GType);

    G_VALUE_COLLECT_INIT (&field.value, type, varargs, 0, &err;;

    if (G_UNLIKELY (err)) {

      g_critical ("%s", err);

      return;

    }

    gst_structure_set_field (structure, &field);

    fieldname = va_arg (varargs, GQuark);

  }

}

/**

 * gst_structure_id_set:

 * @structure: a #GstStructure

 * @fieldname: the GQuark for the name of the field to set

 * @...: variable arguments

 *

 * Identical to gst_structure_set, except that field names are

 * passed using the GQuark for the field name. This allows more efficient

 * setting of the structure if the caller already knows the associated

 * quark values.

 * The last variable argument must be %NULL.

 */

void

gst_structure_id_set (GstStructure * structure, GQuark field, ...)

{

  va_list varargs;

  g_return_if_fail (structure != NULL);

  va_start (varargs, field);

  gst_structure_id_set_valist_internal (structure, field, varargs);

  va_end (varargs);

}

/**

 * gst_structure_id_set_valist:

 * @structure: a #GstStructure

 * @fieldname: the name of the field to set

 * @varargs: variable arguments

 *

 * va_list form of gst_structure_id_set().

 */

void

gst_structure_id_set_valist (GstStructure * structure,

    GQuark fieldname, va_list varargs)

{

  g_return_if_fail (structure != NULL);

  g_return_if_fail (IS_MUTABLE (structure));

  gst_structure_id_set_valist_internal (structure, fieldname, varargs);

}

/**

 * gst_structure_new_id:

 * @name_quark: name of new structure

 * @field_quark: the GQuark for the name of the field to set

 * @...: variable arguments

 *

 * Creates a new #GstStructure with the given name as a GQuark, followed by

 * fieldname quark, GType, argument(s) "triplets" in the same format as

 * gst_structure_id_set(). Basically a convenience wrapper around

 * gst_structure_new_id_empty() and gst_structure_id_set().

 *

 * The last variable argument must be %NULL (or 0).

 *

 * Free-function: gst_structure_free

 *

 * Returns: (transfer full): a new #GstStructure

 */

GstStructure *

gst_structure_new_id (GQuark name_quark, GQuark field_quark, ...)

{

  GstStructure *s;

  va_list varargs;

  g_return_val_if_fail (name_quark != 0, NULL);

  g_return_val_if_fail (field_quark != 0, NULL);

  s = gst_structure_new_id_empty (name_quark);

  va_start (varargs, field_quark);

  gst_structure_id_set_valist_internal (s, field_quark, varargs);

  va_end (varargs);

  return s;

}

#if GST_VERSION_NANO == 1

#define GIT_G_WARNING g_warning

#else

#define GIT_G_WARNING GST_WARNING

#endif

/* If the structure currently contains a field with the same name, it is

 * replaced with the provided field. Otherwise, the field is added to the

 * structure. The field's value is not deeply copied.

 */

static void

gst_structure_set_field (GstStructure * structure, GstStructureField * field)

{

  GstStructureField *f;

  GType field_value_type;

  guint i, len;

  len = GST_STRUCTURE_FIELDS (structure)->len;

  field_value_type = G_VALUE_TYPE (&field->value);

  if (field_value_type == G_TYPE_STRING) {

    const gchar *s;

    s = g_value_get_string (&field->value);

    /* only check for NULL strings in taglists, as they are allowed in message

     * structs, e.g. error message debug strings */

    if (G_UNLIKELY (IS_TAGLIST (structure) && (s == NULL || *s == '\0'))) {

      if (s == NULL) {

        GIT_G_WARNING ("Trying to set NULL string on field '%s' on taglist. "

            "Please file a bug.", g_quark_to_string (field->name));

        g_value_unset (&field->value);

        return;

      } else {

        /* empty strings never make sense */

        GIT_G_WARNING ("Trying to set empty string on taglist field '%s'. "

            "Please file a bug.", g_quark_to_string (field->name));

        g_value_unset (&field->value);

        return;

      }

    } else if (G_UNLIKELY (s != NULL && !g_utf8_validate (s, -1, NULL))) {

      g_warning ("Trying to set string on %s field '%s', but string is not "

          "valid UTF-8. Please file a bug.",

          IS_TAGLIST (structure) ? "taglist" : "structure",

          g_quark_to_string (field->name));

      g_value_unset (&field->value);

      return;

    }

  } else if (G_UNLIKELY (field_value_type == G_TYPE_DATE)) {

    const GDate *d;

    d = g_value_get_boxed (&field->value);

    /* only check for NULL GDates in taglists, as they might make sense

     * in other, generic structs */

    if (G_UNLIKELY ((IS_TAGLIST (structure) && d == NULL))) {

      GIT_G_WARNING ("Trying to set NULL GDate on field '%s' on taglist. "

          "Please file a bug.", g_quark_to_string (field->name));

      g_value_unset (&field->value);

      return;

    } else if (G_UNLIKELY (d != NULL && !g_date_valid (d))) {

      g_warning

          ("Trying to set invalid GDate on %s field '%s'. Please file a bug.",

          IS_TAGLIST (structure) ? "taglist" : "structure",

          g_quark_to_string (field->name));

      g_value_unset (&field->value);

      return;

    }

  }

  for (i = 0; i < len; i++) {

    f = GST_STRUCTURE_FIELD (structure, i);

    if (G_UNLIKELY (f->name == field->name)) {

      g_value_unset (&f->value);

      memcpy (f, field, sizeof (GstStructureField));

      return;

    }

  }

  g_array_append_val (GST_STRUCTURE_FIELDS (structure), *field);

}

/* If there is no field with the given ID, NULL is returned.

 */

static GstStructureField *

gst_structure_id_get_field (const GstStructure * structure, GQuark field_id)

{

  GstStructureField *field;

  guint i, len;

  len = GST_STRUCTURE_FIELDS (structure)->len;

  for (i = 0; i < len; i++) {

    field = GST_STRUCTURE_FIELD (structure, i);

    if (G_UNLIKELY (field->name == field_id))

      return field;

  }

  return NULL;

}

/* If there is no field with the given ID, NULL is returned.

 */

static GstStructureField *

gst_structure_get_field (const GstStructure * structure,

    const gchar * fieldname)

{

  g_return_val_if_fail (structure != NULL, NULL);

  g_return_val_if_fail (fieldname != NULL, NULL);

  return gst_structure_id_get_field (structure,

      g_quark_from_string (fieldname));

}

/**

 * gst_structure_get_value:

 * @structure: a #GstStructure

 * @fieldname: the name of the field to get

 *

 * Get the value of the field with name @fieldname.