Add GstStructure and GstValue

Original commit message from CVS:
Add GstStructure and GstValue

gst/Makefile.am

@@ -112,6 +112,7 @@ libgstreamer_@GST_MAJORMINOR@_la_SOURCES =		\
 	gstqueue.c		\
 	gstquery.c		\
 	gstscheduler.c		\
+	gststructure.c		\
 	gstsystemclock.c	\
 	gstthread.c		\
 	gstthreaddummy.c	\
@@ -121,6 +122,7 @@ libgstreamer_@GST_MAJORMINOR@_la_SOURCES =		\
 	$(GST_URI_SRC)		\
 	gsturitype.c		\
 	gstutils.c		\
+	gstvalue.c		\
 	$(GST_REGISTRY_SRC)	\
 	gstregistrypool.c	\
 	$(GST_PARSE_SRC)	\
@@ -173,6 +175,7 @@ gst_headers =			\
 	gstqueue.h		\
 	gstquery.h		\
 	gstscheduler.h		\
+	gststructure.h		\
 	gstsystemclock.h	\
 	gstthread.h		\
 	gsttrace.h		\
@@ -182,6 +185,7 @@ gst_headers =			\
 	gsturi.h		\
 	gsturitype.h		\
 	gstutils.h		\
+	gstvalue.h		\
 	gstregistry.h		\
 	gstregistrypool.h	\
 	gstparse.h		\

gst/gst.c

@@ -526,6 +526,8 @@ init_post (void)
   _gst_plugin_register_static (&plugin_desc);
  
   _gst_cpu_initialize (_gst_enable_cpu_opt);
+  _gst_structure_initialize ();
+  _gst_value_initialize ();
   _gst_props_initialize ();
   _gst_caps_initialize ();
   _gst_plugin_initialize ();

gst/gst.h

@@ -44,6 +44,7 @@
 #include <gst/gsttypefind.h>
 #include <gst/gstautoplug.h>
 #include <gst/gstcaps.h>
+#include <gst/gststructure.h>
 #include <gst/gstprops.h>
 #include <gst/gstplugin.h>
 #include <gst/gsturi.h>
@@ -56,6 +57,7 @@
 #include <gst/gstclock.h>
 #include <gst/gstsystemclock.h>
 #include <gst/gstinterface.h>
+#include <gst/gstvalue.h>
 
 #include <gst/gstparse.h>
 #include <gst/gstregistry.h>

gst/gststructure.c

@@ -0,0 +1,853 @@
+/* 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <string.h>
+
+#include <gst/gst.h>
+#include <gobject/gvaluecollector.h>
+
+//#define G_TYPE_FOURCC G_TYPE_FLOAT
+
+static GType _gst_structure_type;
+
+static void _gst_structure_transform_to_string(const GValue *src_value,
+    GValue *dest_value);
+
+static void _gst_structure_value_init (GValue *value);
+static void _gst_structure_value_free (GValue *value);
+static void _gst_structure_value_copy (const GValue *src, GValue *dest);
+static gpointer _gst_structure_value_peek_pointer (const GValue *value);
+
+
+GType gst_structure_get_type(void)
+{
+  return _gst_structure_type;
+}
+
+void _gst_structure_initialize(void)
+{
+  static GTypeValueTable type_value_table = {
+    _gst_structure_value_init,
+    _gst_structure_value_free,
+    _gst_structure_value_copy,
+    _gst_structure_value_peek_pointer,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+  };
+  static GTypeInfo structure_info = {
+    0,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    0, /* sizeof(GstStructure), */
+    0,
+    NULL, /* _gst_structure_init, */
+    &type_value_table,
+  };
+
+  _gst_structure_type = g_type_register_static(G_TYPE_BOXED, "GstStructure",
+      &structure_info, 0);
+#if 0
+  _gst_structure_type = g_boxed_type_register_static("GstStructure",
+      (GBoxedCopyFunc) gst_structure_dup,
+      (GBoxedFreeFunc) gst_structure_free);
+#endif
+
+  g_value_register_transform_func(_gst_structure_type, G_TYPE_STRING,
+      _gst_structure_transform_to_string);
+}
+
+/**
+ * gst_structure_empty_new:
+ * @name: name of new structure
+ *
+ * Creates a new, empty #GstStructure with the given name.
+ *
+ * Returns: a new, empty #GstStructure
+ */
+GstStructure *gst_structure_empty_new(const gchar *name)
+{
+  GstStructure *structure;
+
+  g_return_val_if_fail(name != NULL, NULL);
+
+  structure = g_new0(GstStructure, 1);
+  structure->name = g_quark_from_string(name);
+  structure->fields = g_array_new(FALSE,TRUE,sizeof(GstStructureField));
+
+  return structure;
+}
+
+/**
+ * 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.
+ *
+ * Returns: a new #GstStructure
+ */
+GstStructure *gst_structure_new(const gchar *name,
+    const gchar *firstfield, ...)
+{
+  GstStructure *structure;
+  va_list varargs;
+
+  g_return_val_if_fail(name != NULL, NULL);
+
+  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
+ * @varags: 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.
+ *
+ * Returns: a new #GstStructure
+ */
+GstStructure *gst_structure_new_valist(const gchar *name,
+    const gchar *firstfield, va_list varargs)
+{
+  GstStructure *structure;
+
+  g_return_val_if_fail(name != NULL, NULL);
+
+  structure = gst_structure_empty_new(name);
+  gst_structure_set_valist(structure, firstfield, varargs);
+
+  return structure;
+}
+
+/**
+ * gst_structure_dup:
+ * @structure: a #GstStructure to duplicate
+ *
+ * Duplicates a #GstStructure and all its fields and values.
+ *
+ * Returns: a new #GstStructure.
+ */
+GstStructure *gst_structure_dup(GstStructure *structure)
+{
+  GstStructure *new_structure;
+  GstStructureField *field;
+  int i;
+
+  g_return_val_if_fail(structure != NULL, NULL);
+
+  new_structure = gst_structure_empty_new(g_quark_to_string(structure->name));
+  new_structure->fields = g_array_set_size(new_structure->fields,
+      structure->fields->len);
+  new_structure->name = structure->name;
+
+  for(i=0;i<structure->fields->len;i++){
+    GstStructureField new_field = { 0 };
+
+    field = GST_STRUCTURE_FIELD(structure, i);
+
+    new_field.name = field->name;
+    g_value_init(&new_field.value, G_VALUE_TYPE(&field->value));
+    g_value_copy(&field->value, &new_field.value);
+
+    g_array_append_val(new_structure->fields, new_field);
+  }
+
+  return structure;
+}
+
+/**
+ * gst_structure_free: 
+ * @structure: the #GstStructure to free
+ *
+ * Frees a #GstStructure and all its fields and values.
+ */
+void gst_structure_free(GstStructure *structure)
+{
+  GstStructureField *field;
+  int i;
+
+  return;
+
+  g_return_if_fail(structure != NULL);
+
+  for(i=0;i<structure->fields->len;i++){
+    field = GST_STRUCTURE_FIELD(structure, i);
+
+    if(G_IS_VALUE(&field->value)){
+      g_value_unset(&field->value);
+    }
+  }
+  g_free(structure);
+}
+
+/**
+ * gst_structure_get_name:
+ * @structure: a #GstStructure
+ *
+ * Accessor fuction.
+ *
+ * Returns: the name of the structure.
+ */
+const gchar *gst_structure_get_name(GstStructure *structure)
+{
+  g_return_val_if_fail(structure != NULL, NULL);
+
+  return g_quark_to_string(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.
+ */
+void gst_structure_set_name(GstStructure *structure, const gchar *name)
+{
+  g_return_if_fail(structure != NULL);
+  g_return_if_fail(name != NULL);
+
+  structure->name = g_quark_from_string(name);
+}
+
+/**
+ * gst_structure_id_set_value:
+ * @structure: a #GstStructure
+ * @field_id: a #GQuark representing a field
+ * @value: the new value of the field
+ *
+ * Sets the field with the given ID to the provided value.  If the field
+ * does not exist, it is created.  If the field exists, the previous
+ * value is freed.
+ */
+void gst_structure_id_set_value(GstStructure *structure, GQuark fieldname,
+    GValue *value)
+{
+  GstStructureField field = { 0 };
+
+  g_return_if_fail(structure != NULL);
+  g_return_if_fail(G_IS_VALUE(value));
+
+  field.name = fieldname;
+  g_value_init(&field.value, G_TYPE_INT);
+  g_value_copy(value, &field.value);
+
+  gst_structure_set_field(structure, &field);
+}
+
+/**
+ * gst_structure_set_value:
+ * @structure: a #GstStructure
+ * @field: the name of the field to set
+ * @value: the new value of the field
+ *
+ * Sets the field with the given name to the provided value.  If the field
+ * does not exist, it is created.  If the field exists, the previous
+ * value is freed.
+ */
+void gst_structure_set_value(GstStructure *structure, const gchar *field,
+    GValue *value)
+{
+  g_return_if_fail(structure != NULL);
+  g_return_if_fail(field != NULL);
+  g_return_if_fail(G_IS_VALUE(value));
+
+  gst_structure_id_set_value(structure, g_quark_from_string(field), value);
+}
+
+/**
+ * gst_structure_set:
+ * @structure: a #GstStructure
+ * @field: the name of the field to set
+ * @...: variable arguments
+ *
+ * Parses the variable arguments and sets fields accordingly.
+ * Variable arguments should be in the form field name, field type
+ * (as a GType), value.  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);
+
+  va_start(varargs, field);
+
+  gst_structure_set_valist(structure,field,varargs);
+
+  va_end(varargs);
+}
+
+/**
+ * gst_structure_set:
+ * @structure: a #GstStructure
+ * @field: 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)
+{
+  GType type;
+  int i;
+  double d;
+  char *s;
+
+  g_return_if_fail(structure != NULL);
+
+  while(fieldname){
+    GstStructureField field = { 0 };
+
+    field.name = g_quark_from_string(fieldname);
+
+    type = va_arg (varargs, GType); 
+
+    switch(type){
+      case G_TYPE_INT:
+	i = va_arg(varargs, int);
+        g_value_init(&field.value, G_TYPE_INT);
+        g_value_set_int(&field.value, i);
+	break;
+      case G_TYPE_DOUBLE:
+	d = va_arg(varargs, double);
+        g_value_init(&field.value, G_TYPE_DOUBLE);
+        g_value_set_double(&field.value, d);
+	break;
+#if 0
+      case GST_TYPE_FOURCC:
+	i = va_arg(varargs, int);
+        g_value_init(&field.value, G_TYPE_FOURCC);
+        gst_value_set_fourcc(&field.value, i);
+	break;
+#endif
+      case G_TYPE_BOOLEAN:
+	i = va_arg(varargs, int);
+        g_value_init(&field.value, G_TYPE_BOOLEAN);
+        g_value_set_boolean(&field.value, i);
+	break;
+      case G_TYPE_STRING:
+	s = va_arg(varargs, char *);
+        g_value_init(&field.value, G_TYPE_STRING);
+        g_value_set_string(&field.value, s);
+	break;
+      default:
+	g_assert_not_reached();
+	break;
+    }
+
+    gst_structure_set_field(structure, &field);
+
+    fieldname = va_arg (varargs, gchar *);
+  }
+}
+
+/**
+ * gst_structure_set_field:
+ * @structure: a #GstStructure
+ * @field: the #GstStructureField to set
+ *
+ * Sets a field in the structure.  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.
+ *
+ * This function is intended mainly for internal use.  The function
+ * #gst_structure_set() is recommended instead of this one.
+ */
+void gst_structure_set_field(GstStructure *structure, GstStructureField *field)
+{
+  GstStructureField *f;
+  int i;
+
+  for(i=0;i<structure->fields->len;i++){
+    f = GST_STRUCTURE_FIELD(structure, i);
+
+    if(f->name == field->name){
+      g_value_unset(&f->value);
+      memcpy(f,field,sizeof(GstStructureField));
+      return;
+    }
+  }
+
+  g_array_append_val(structure->fields, *field);
+}
+
+/**
+ * gst_structure_id_get_field:
+ * @structure: a #GstStructure
+ * @field_id: the GQuark of the field to get
+ *
+ * Gets the specified field from the structure.  If there is no
+ * field with the given ID, NULL is returned.
+ *
+ * Returns: the #GstStructureField with the given ID
+ */
+GstStructureField *gst_structure_id_get_field(GstStructure *structure,
+    GQuark field_id)
+{
+  GstStructureField *field;
+  int i;
+
+  g_return_val_if_fail(structure != NULL, NULL);
+
+  for(i=0;i<structure->fields->len;i++){
+    field = GST_STRUCTURE_FIELD(structure, i);
+
+    if(field->name == field_id) return field;
+  }
+
+  return NULL;
+}
+
+/**
+ * gst_structure_get_field:
+ * @structure: a #GstStructure
+ * @fieldname: the name of the field to get
+ *
+ * Gets the specified field from the structure.  If there is no
+ * field with the given ID, NULL is returned.
+ *
+ * Returns: the #GstStructureField with the given name
+ */
+GstStructureField *
+gst_structure_get_field(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:
+ * @structure: a #GstStructure
+ * @fieldname: the name of the field to get
+ *
+ * Accessor function.
+ *
+ * Returns: the #GValue corresponding to the field with the given name.
+ */
+const GValue *
+gst_structure_get(GstStructure *structure, const gchar *fieldname)
+{
+  GstStructureField *field;
+
+  g_return_val_if_fail(structure != NULL, NULL);
+  g_return_val_if_fail(fieldname != NULL, NULL);
+
+  field = gst_structure_get_field(structure, fieldname);
+  if(field == NULL) return NULL;
+
+  return &field->value;
+}
+
+/**
+ * gst_structure_remove_field:
+ * @structure: a #GstStructure
+ * @fieldname: the name of the field to remove
+ *
+ * Removes the field with the given name.  If the field with the given
+ * name does not exist, the structure is unchanged.
+ */
+void
+gst_structure_remove_field(GstStructure *structure, const gchar *fieldname)
+{
+  GstStructureField *field;
+  GQuark id;
+  int i;
+
+  g_return_if_fail(structure != NULL);
+  g_return_if_fail(fieldname != NULL);
+
+  id = g_quark_from_string(fieldname);
+
+  for(i=0;i<structure->fields->len;i++){
+    field = GST_STRUCTURE_FIELD(structure, i);
+
+    if(field->name == id){
+      if(G_IS_VALUE(&field->value)){
+        g_value_unset(&field->value);
+      }
+      structure->fields = g_array_remove_index(structure->fields, i);
+      return;
+    }
+  }
+}
+
+/**
+ * gst_structure_get_field_type:
+ * @structure: a #GstStructure
+ * @fieldname: the name of the field
+ *
+ * Finds the field with the given name, and returns the type of the
+ * value it contains.  If the field is not found, G_TYPE_NONE is
+ * returned.
+ *
+ * Returns: the #GValue of the field
+ */
+GType
+gst_structure_get_field_type(GstStructure *structure, const gchar *fieldname)
+{
+  GstStructureField *field;
+
+  g_return_val_if_fail(structure != NULL, G_TYPE_NONE);
+  g_return_val_if_fail(fieldname != NULL, G_TYPE_NONE);
+
+  field = gst_structure_get_field(structure, fieldname);
+  if(field == NULL) return G_TYPE_NONE;
+
+  return G_VALUE_TYPE(&field->value);
+}
+
+/**
+ * gst_structure_n_fields:
+ * @structure: a #GstStructure
+ *
+ * Accessor function.
+ *
+ * Returns: the number of fields in the structure
+ */
+gint
+gst_structure_n_fields(GstStructure *structure)
+{
+  g_return_val_if_fail(structure != NULL, 0);
+
+  return structure->fields->len;
+}
+
+/**
+ * gst_structure_has_field:
+ * @structure: a #GstStructure
+ * @fieldname: the name of a field
+ *
+ * Accessor function.
+ *
+ * Returns: TRUE if the structure contains a field with the given name
+ */
+gboolean
+gst_structure_has_field(GstStructure *structure, const gchar *fieldname)
+{
+  GstStructureField *field;
+
+  g_return_val_if_fail(structure != NULL, 0);
+  g_return_val_if_fail(fieldname != NULL, 0);
+
+  field = gst_structure_get_field(structure, fieldname);
+
+  return (field != NULL);
+}
+
+/**
+ * gst_structure_has_field:
+ * @structure: a #GstStructure
+ * @fieldname: the name of a field
+ * @type: the type of a value
+ *
+ * Accessor function.
+ *
+ * Returns: TRUE if the structure contains a field with the given name and type
+ */
+gboolean
+gst_structure_has_field_typed(GstStructure *structure, const gchar *fieldname,
+    GType type)
+{
+  GstStructureField *field;
+
+  g_return_val_if_fail(structure != NULL, 0);
+  g_return_val_if_fail(fieldname != NULL, 0);
+
+  field = gst_structure_get_field(structure, fieldname);
+  if(field == NULL) return FALSE;
+
+  return (G_VALUE_TYPE(&field->value) == type);
+}
+
+
+/* utility functions */
+
+/**
+ * gst_structure_get_boolean:
+ * @structure: a #GstStructure
+ * @fieldname: the name of a field
+ * @ptr: a pointer to a #gboolean to set
+ *
+ * Sets the boolean pointed to by @ptr corresponding to the value of the
+ * given field.  Caller is responsible for making sure the field exists
+ * and has the correct type.
+ *
+ * Returns: TRUE if the value could be set correctly
+ */
+gboolean
+gst_structure_get_boolean(GstStructure *structure, const gchar *fieldname,
+    gboolean *value)
+{
+  GstStructureField *field;
+
+  g_return_val_if_fail(structure != NULL, FALSE);
+  g_return_val_if_fail(fieldname != NULL, FALSE);
+
+  field = gst_structure_get_field(structure, fieldname);
+
+  if(field == NULL) return FALSE;
+  if(!G_VALUE_HOLDS_BOOLEAN(&field->value))return FALSE;
+
+  *value = g_value_get_boolean(&field->value);
+
+  return TRUE;
+}
+
+/**
+ * gst_structure_get_int:
+ * @structure: a #GstStructure
+ * @fieldname: the name of a field
+ * @ptr: a pointer to an int to set
+ *
+ * Sets the int pointed to by @ptr corresponding to the value of the
+ * given field.  Caller is responsible for making sure the field exists
+ * and has the correct type.
+ *
+ * Returns: TRUE if the value could be set correctly
+ */
+gboolean
+gst_structure_get_int(GstStructure *structure, const gchar *fieldname,
+    gint *value)
+{
+  GstStructureField *field;
+
+  g_return_val_if_fail(structure != NULL, FALSE);
+  g_return_val_if_fail(fieldname != NULL, FALSE);
+  g_return_val_if_fail(value != NULL, FALSE);
+
+  field = gst_structure_get_field(structure, fieldname);
+
+  if(field == NULL) return FALSE;
+  if(!G_VALUE_HOLDS_INT(&field->value))return FALSE;
+
+  *value = g_value_get_int(&field->value);
+
+  return TRUE;
+}
+
+/**
+ * gst_structure_get_fourcc:
+ * @structure: a #GstStructure
+ * @fieldname: the name of a field
+ * @ptr: a pointer to a #GstFourcc to set
+ *
+ * Sets the #GstFourcc pointed to by @ptr corresponding to the value of the
+ * given field.  Caller is responsible for making sure the field exists
+ * and has the correct type.
+ *
+ * Returns: TRUE if the value could be set correctly
+ */
+gboolean
+gst_structure_get_fourcc(GstStructure *structure, const gchar *fieldname,
+    guint32 *value)
+{
+  GstStructureField *field;
+
+  g_return_val_if_fail(structure != NULL, FALSE);
+  g_return_val_if_fail(fieldname != NULL, FALSE);
+  g_return_val_if_fail(value != NULL, FALSE);
+
+  field = gst_structure_get_field(structure, fieldname);
+
+  if(field == NULL) return FALSE;
+  if(!G_VALUE_HOLDS_UINT(&field->value))return FALSE;
+
+  *value = g_value_get_uint(&field->value);
+
+  return TRUE;
+}
+
+/**
+ * gst_structure_get_double:
+ * @structure: a #GstStructure
+ * @fieldname: the name of a field
+ * @ptr: a pointer to a #GstFourcc to set
+ *
+ * Sets the double pointed to by @ptr corresponding to the value of the
+ * given field.  Caller is responsible for making sure the field exists
+ * and has the correct type.
+ *
+ * Returns: TRUE if the value could be set correctly
+ */
+gboolean gst_structure_get_double(GstStructure *structure,
+    const gchar *fieldname, gdouble *value)
+{
+  GstStructureField *field;
+
+  g_return_val_if_fail(structure != NULL, FALSE);
+  g_return_val_if_fail(fieldname != NULL, FALSE);
+  g_return_val_if_fail(value != NULL, FALSE);
+
+  field = gst_structure_get_field(structure, fieldname);
+
+  if(field == NULL) return FALSE;
+  if(!G_VALUE_HOLDS_DOUBLE(&field->value))return FALSE;
+
+  *value = g_value_get_double(&field->value);
+
+  return TRUE;
+}
+
+/**
+ * gst_structure_get_string:
+ * @structure: a #GstStructure
+ * @fieldname: the name of a field
+ * @ptr: a pointer to a #GstFourcc to set
+ *
+ * Finds the field corresponding to @fieldname, and returns the string
+ * contained in the field's value.  Caller is responsible for making
+ * sure the field exists and has the correct type.
+ *
+ * The string should not be modified, and remains valid until the next
+ * call to a gst_structure_*() function with the given structure.
+ *
+ * Returns: a pointer to the string
+ */
+const gchar *
+gst_structure_get_string(GstStructure *structure, const gchar *fieldname)
+{
+  GstStructureField *field;
+
+  g_return_val_if_fail(structure != NULL, NULL);
+  g_return_val_if_fail(fieldname != NULL, NULL);
+
+  field = gst_structure_get_field(structure, fieldname);
+
+  if(field == NULL) return FALSE;
+  if(!G_VALUE_HOLDS_STRING(&field->value))return FALSE;
+
+  return g_value_get_string(&field->value);
+}
+
+/**
+ * gst_structure_to_string:
+ * @structure: a #GstStructure
+ *
+ * Converts @structure to a human-readable representation.
+ * 
+ * Returns: a pointer to string allocated by g_malloc()
+ */
+gchar *
+gst_structure_to_string(GstStructure *structure)
+{
+  GstStructureField *field;
+  GString *s;
+  int i;
+
+  g_return_val_if_fail(structure != NULL, NULL);
+
+  s = g_string_new("");
+  g_string_append_printf(s, "\"%s\"", g_quark_to_string(structure->name));
+  for(i=0;i<structure->fields->len;i++){
+    GValue s_val = { 0 };
+
+    field = GST_STRUCTURE_FIELD(structure, i);
+
+    g_value_init(&s_val, G_TYPE_STRING);
+
+    g_value_transform(&field->value, &s_val);
+    g_string_append_printf(s, ", %s:%s", g_quark_to_string(field->name),
+	g_value_get_string(&s_val));
+    g_value_unset(&s_val);
+  }
+  return g_string_free(s, FALSE);
+}
+
+/**
+ * gst_structure_from_string:
+ * @structure: a #GstStructure
+ *
+ * Creates a #GstStructure from a string representation.
+ * 
+ * Returns: a new #GstStructure
+ */
+GstStructure *
+gst_structure_from_string (const gchar *string)
+{
+  /* FIXME */
+
+  g_return_val_if_fail(string != NULL, NULL);
+
+  g_assert_not_reached();
+
+  return NULL;
+}
+
+static void
+_gst_structure_transform_to_string(const GValue *src_value, GValue *dest_value)
+{
+  g_return_if_fail(src_value != NULL);
+  g_return_if_fail(dest_value != NULL);
+
+  dest_value->data[0].v_pointer =
+    gst_structure_to_string (src_value->data[0].v_pointer);
+}
+
+
+static void _gst_structure_value_init (GValue *value)
+{
+  value->data[0].v_pointer = gst_structure_empty_new("");
+}
+
+static void _gst_structure_value_free (GValue *value)
+{
+  gst_structure_free(value->data[0].v_pointer);
+
+}
+
+static void _gst_structure_value_copy (const GValue *src, GValue *dest)
+{
+  dest->data[0].v_pointer = gst_structure_dup(src->data[0].v_pointer);
+}
+
+static gpointer _gst_structure_value_peek_pointer (const GValue *value)
+{
+  return value->data[0].v_pointer;
+}
+

gst/gststructure.h

@@ -0,0 +1,104 @@
+/* GStreamer
+ * Copyright (C) <2003> David A. Schleef <ds@schleef.org>
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GST_STRUCTURE_H__
+#define __GST_STRUCTURE_H__
+
+#include <gst/gstconfig.h>
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+typedef struct _GstStructure GstStructure;
+typedef struct _GstStructureField GstStructureField;
+
+struct _GstStructure {
+  int len;
+
+  GQuark name;
+
+  GArray *fields;
+};
+
+struct _GstStructureField {
+  GQuark name;
+  GValue value;
+};
+
+#define GST_STRUCTURE_FIELD(structure, index) \
+    &g_array_index((structure)->fields, GstStructureField, (index))
+
+GType gst_structure_get_type(void);
+void _gst_structure_initialize(void);
+
+GstStructure *gst_structure_empty_new(const gchar *name);
+GstStructure *gst_structure_new(const gchar *name,
+    const gchar *firstfield, ...);
+GstStructure *gst_structure_new_valist(const gchar *name,
+    const gchar *firstfield, va_list varargs);
+GstStructure *gst_structure_dup(GstStructure *structure);
+void gst_structure_free(GstStructure *structure);
+
+const gchar *gst_structure_get_name(GstStructure *structure);
+void gst_structure_set_name(GstStructure *structure, const gchar *name);
+void gst_structure_set_field(GstStructure *structure,
+    GstStructureField *field);
+
+void gst_structure_id_set_value(GstStructure *structure, GQuark field,
+    GValue *value);
+void gst_structure_set_value(GstStructure *structure, const gchar *field,
+    GValue *value);
+void gst_structure_set(GstStructure *structure, const gchar *field, ...);
+void gst_structure_set_valist(GstStructure *structure, const gchar *field,
+    va_list varargs);
+const GValue *gst_structure_get(GstStructure *structure, const gchar *field);
+GstStructureField *gst_structure_get_field(GstStructure *structure,
+        const gchar *fieldname);
+GstStructureField *gst_structure_id_get_field(GstStructure *structure,
+        GQuark fieldname);
+void gst_structure_remove_field(GstStructure *structure, const gchar *field);
+
+GType gst_structure_get_field_type(GstStructure *structure,
+    const gchar *field);
+gint gst_structure_n_fields(GstStructure *structure);
+gboolean gst_structure_has_field(GstStructure *structure, const gchar *field);
+gboolean gst_structure_has_field_typed(GstStructure *structure,
+    const gchar *field, GType type);
+
+/* utility functions */
+
+gboolean gst_structure_get_boolean(GstStructure *structure, const gchar *field,
+    gboolean *value);
+gboolean gst_structure_get_int(GstStructure *structure, const gchar *field,
+    gint *value);
+gboolean gst_structure_get_fourcc(GstStructure *structure, const gchar *field,
+    guint32 *value);
+gboolean gst_structure_get_double(GstStructure *structure, const gchar *field,
+    gdouble *value);
+const gchar *gst_structure_get_string(GstStructure *structure,
+    const gchar *field);
+
+gchar * gst_structure_to_string(GstStructure *structure);
+GstStructure * gst_structure_from_string (const gchar *string);
+
+
+G_END_DECLS
+
+#endif
+

gst/gstvalue.c

@@ -0,0 +1,217 @@
+/* GStreamer
+ * Copyright (C) <2003> David A. Schleef <ds@schleef.org>
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gst/gst.h>
+#include <gobject/gvaluecollector.h>
+
+
+GType gst_type_fourcc;
+GType gst_type_int_range;
+GType gst_type_double_range;
+
+static void 
+gst_value_init_fourcc (GValue *value)
+{
+  value->data[0].v_long = 0;
+}
+
+static void
+gst_value_copy_fourcc (const GValue *src_value, GValue *dest_value)
+{
+  dest_value->data[0].v_long = src_value->data[0].v_long;
+}
+
+static gchar *
+gst_value_collect_fourcc (GValue *value, guint n_collect_values,
+    GTypeCValue *collect_values, guint collect_flags)
+{
+  value->data[0].v_long = collect_values[0].v_long;
+
+  return NULL;
+}
+
+static gchar *
+gst_value_lcopy_fourcc (const GValue *value, guint n_collect_values,
+    GTypeCValue *collect_values, guint collect_flags)
+{
+  guint32 *fourcc_p = collect_values[0].v_pointer;
+
+  if (!fourcc_p)
+    return g_strdup_printf ("value location for `%s' passed as NULL",
+	G_VALUE_TYPE_NAME (value));
+
+  *fourcc_p = value->data[0].v_long;
+
+  return NULL;
+}
+
+void
+gst_value_set_fourcc (GValue *value, guint32 fourcc)
+{
+  g_return_if_fail (GST_VALUE_HOLDS_FOURCC (value));
+
+  value->data[0].v_long = fourcc;
+}
+
+guint32
+gst_value_get_fourcc (const GValue *value)
+{
+  g_return_val_if_fail (GST_VALUE_HOLDS_FOURCC (value), 0);
+
+  return value->data[0].v_long;
+}
+
+/* int range */
+
+static void 
+gst_value_init_int_range (GValue *value)
+{
+  value->data[0].v_long = 0;
+}
+
+static void
+gst_value_copy_int_range (const GValue *src_value, GValue *dest_value)
+{
+  dest_value->data[0].v_long = src_value->data[0].v_long;
+}
+
+static gchar *
+gst_value_collect_int_range (GValue *value, guint n_collect_values,
+    GTypeCValue *collect_values, guint collect_flags)
+{
+  value->data[0].v_long = collect_values[0].v_long;
+
+  return NULL;
+}
+
+static gchar *
+gst_value_lcopy_int_range (const GValue *value, guint n_collect_values,
+    GTypeCValue *collect_values, guint collect_flags)
+{
+  guint32 *int_range_p = collect_values[0].v_pointer;
+
+  if (!int_range_p)
+    return g_strdup_printf ("value location for `%s' passed as NULL",
+	G_VALUE_TYPE_NAME (value));
+
+  *int_range_p = value->data[0].v_long;
+
+  return NULL;
+}
+
+void
+gst_value_set_int_range (GValue *value, int start, int end)
+{
+  g_return_if_fail (GST_VALUE_HOLDS_FOURCC (value));
+
+  value->data[0].v_long = start;
+  value->data[1].v_long = end;
+}
+
+int
+gst_value_get_int_range_start (const GValue *value)
+{
+  g_return_val_if_fail (GST_VALUE_HOLDS_FOURCC (value), 0);
+
+  return value->data[0].v_long;
+}
+
+int
+gst_value_get_int_range_end (const GValue *value)
+{
+  g_return_val_if_fail (GST_VALUE_HOLDS_FOURCC (value), 0);
+
+  return value->data[1].v_long;
+}
+
+static void
+gst_value_transform_fourcc_string (const GValue *src_value,
+    GValue *dest_value)
+{
+  dest_value->data[0].v_pointer = g_strdup_printf(GST_FOURCC_FORMAT,
+      GST_FOURCC_ARGS(src_value->data[0].v_long));
+}
+
+static void
+gst_value_transform_int_range_string (const GValue *src_value,
+    GValue *dest_value)
+{
+  dest_value->data[0].v_pointer = g_strdup_printf("[%d,%d]",
+      (int)src_value->data[0].v_long, (int)src_value->data[1].v_long);
+}
+
+
+void
+_gst_value_initialize (void)
+{
+  GTypeInfo info = {
+    0,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    0,
+    0,
+    NULL,
+    NULL,
+  };
+  //const GTypeFundamentalInfo finfo = { G_TYPE_FLAG_DERIVABLE, };
+
+  {
+    static const GTypeValueTable value_table = {
+      gst_value_init_fourcc,
+      NULL,
+      gst_value_copy_fourcc,
+      NULL,
+      "i",
+      gst_value_collect_fourcc,
+      "p",
+      gst_value_lcopy_fourcc
+    };
+    info.value_table = &value_table;
+    gst_type_fourcc = g_type_register_static (G_TYPE_BOXED, "GstFourcc", &info, 0);
+  }
+
+  {
+    static const GTypeValueTable value_table = {
+      gst_value_init_int_range,
+      NULL,
+      gst_value_copy_int_range,
+      NULL,
+      "i",
+      gst_value_collect_int_range,
+      "p",
+      gst_value_lcopy_int_range
+    };
+    info.value_table = &value_table;
+    gst_type_int_range = g_type_register_static (G_TYPE_BOXED, "GstIntRange", &info, 0);
+  }
+
+  g_value_register_transform_func (GST_TYPE_FOURCC, G_TYPE_STRING,
+      gst_value_transform_fourcc_string);
+  g_value_register_transform_func (GST_TYPE_INT_RANGE, G_TYPE_STRING,
+      gst_value_transform_int_range_string);
+}
+
+

gst/gstvalue.h

@@ -0,0 +1,54 @@
+/* GStreamer
+ * Copyright (C) <2003> David A. Schleef <ds@schleef.org>
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GST_VALUE_H__
+#define __GST_VALUE_H__
+
+#include <gst/gstconfig.h>
+
+G_BEGIN_DECLS
+
+#define GST_VALUE_HOLDS_FOURCC(x) TRUE
+
+#define GST_TYPE_FOURCC gst_type_fourcc
+#define GST_TYPE_INT_RANGE gst_type_int_range
+#define GST_TYPE_DOUBLE_RANGE gst_type_double_range
+
+extern GType gst_type_fourcc;
+extern GType gst_type_int_range;
+extern GType gst_type_double_range;
+
+void gst_value_set_fourcc (GValue *value, guint32 fourcc);
+guint32 gst_value_get_fourcc (const GValue *value);
+
+void gst_value_set_int_range (GValue *value, int start, int end);
+int gst_value_get_int_range_start (const GValue *value);
+int gst_value_get_int_range_end (const GValue *value);
+
+void gst_value_set_double_range (GValue *value, double start, double end);
+double gst_value_get_double_range_start (const GValue *value);
+double gst_value_get_double_range_end (const GValue *value);
+
+void _gst_value_initialize (void);
+
+G_END_DECLS
+
+#endif
+
+