1 /* GObject - GLib Type, Object, Parameter and Signal Library
2 * Copyright (C) 1997-1999, 2000-2001 Tim Janik and Red Hat, Inc.
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General
15 * Public License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
17 * Boston, MA 02111-1307, USA.
19 * gvalue.h: generic GValue functions
24 #if !defined (__GLIB_GOBJECT_H_INSIDE__) && !defined (GOBJECT_COMPILATION)
25 #error "Only <glib-object.h> can be included directly."
28 #include <gobject/gtype.h>
32 /* --- type macros --- */
35 * @type: A #GType value.
37 * Checks whether the passed in type ID can be used for g_value_init().
38 * That is, this macro checks whether this type provides an implementation
39 * of the #GTypeValueTable functions required for a type to create a #GValue of.
41 * Returns: Whether @type is suitable as a #GValue type.
43 #define G_TYPE_IS_VALUE(type) (g_type_check_is_value_type (type))
46 * @value: A #GValue structure.
48 * Checks if @value is a valid and initialized #GValue structure.
50 * Returns: %TRUE on success.
52 #define G_IS_VALUE(value) (G_TYPE_CHECK_VALUE (value))
55 * @value: A #GValue structure.
57 * Get the type identifier of @value.
59 * Returns: the #GType.
61 #define G_VALUE_TYPE(value) (((GValue*) (value))->g_type)
64 * @value: A #GValue structure.
66 * Gets the type name of @value.
68 * Returns: the type name.
70 #define G_VALUE_TYPE_NAME(value) (g_type_name (G_VALUE_TYPE (value)))
73 * @value: A #GValue structure.
74 * @type: A #GType value.
76 * Checks if @value holds (or contains) a value of @type.
77 * This macro will also check for @value != %NULL and issue a
78 * warning if the check fails.
80 * Returns: %TRUE if @value holds the @type.
82 #define G_VALUE_HOLDS(value,type) (G_TYPE_CHECK_VALUE_TYPE ((value), (type)))
85 /* --- typedefs & structures --- */
88 * @src_value: Source value.
89 * @dest_value: Target value.
91 * The type of value transformation functions which can be registered with
92 * g_value_register_transform_func().
94 typedef void (*GValueTransform
) (const GValue
*src_value
,
99 * An opaque structure used to hold different types of values.
100 * The data within the structure has protected scope: it is accessible only
101 * to functions within a #GTypeValueTable structure, or implementations of
102 * the g_value_*() API. That is, code portions which implement new fundamental
104 * #GValue users cannot make any assumptions about how data is stored
105 * within the 2 element @data union, and the @g_type member should
106 * only be accessed through the G_VALUE_TYPE() macro.
113 /* public for GTypeValueTable methods */
128 /* --- prototypes --- */
129 GLIB_AVAILABLE_IN_ALL
130 GValue
* g_value_init (GValue
*value
,
132 GLIB_AVAILABLE_IN_ALL
133 void g_value_copy (const GValue
*src_value
,
135 GLIB_AVAILABLE_IN_ALL
136 GValue
* g_value_reset (GValue
*value
);
137 GLIB_AVAILABLE_IN_ALL
138 void g_value_unset (GValue
*value
);
139 GLIB_AVAILABLE_IN_ALL
140 void g_value_set_instance (GValue
*value
,
144 /* --- private --- */
145 GLIB_AVAILABLE_IN_ALL
146 gboolean
g_value_fits_pointer (const GValue
*value
);
147 GLIB_AVAILABLE_IN_ALL
148 gpointer
g_value_peek_pointer (const GValue
*value
);
151 /* --- implementation details --- */
152 GLIB_AVAILABLE_IN_ALL
153 gboolean
g_value_type_compatible (GType src_type
,
155 GLIB_AVAILABLE_IN_ALL
156 gboolean
g_value_type_transformable (GType src_type
,
158 GLIB_AVAILABLE_IN_ALL
159 gboolean
g_value_transform (const GValue
*src_value
,
161 GLIB_AVAILABLE_IN_ALL
162 void g_value_register_transform_func (GType src_type
,
164 GValueTransform transform_func
);
167 * G_VALUE_NOCOPY_CONTENTS:
169 * If passed to G_VALUE_COLLECT(), allocated data won't be copied
170 * but used verbatim. This does not affect ref-counted types like
173 #define G_VALUE_NOCOPY_CONTENTS (1 << 27)
178 * A #GValue must be initialized before it can be used.
179 * This macro can be used as initializer instead of an explicit
180 * <literal>{ 0 }</literal> when declaring a variable,
181 * but it cannot be assigned to a variable.
184 * GValue value = G_VALUE_INIT;
189 #define G_VALUE_INIT { 0, { { 0 } } }
194 #endif /* __G_VALUE_H__ */