1 /* GObject - GLib Type, Object, Parameter and Signal Library 2 * Copyright (C) 1997-1999, 2000-2001 Tim Janik and Red Hat, Inc. 3 * 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 2.1 of the License, or (at your option) any later version. 8 * 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. 13 * 14 * You should have received a copy of the GNU Lesser General 15 * Public License along with this library; if not, see <http://www.gnu.org/licenses/>. 16 * 17 * gvalue.h: generic GValue functions 18 */ 19 #ifndef __G_VALUE_H__ 20 #define __G_VALUE_H__ 21 22 #if !defined (__GLIB_GOBJECT_H_INSIDE__) && !defined (GOBJECT_COMPILATION) 23 #error "Only <glib-object.h> can be included directly." 24 #endif 25 26 #include <gobject/gtype.h> 27 28 G_BEGIN_DECLS 29 30 /* --- type macros --- */ 31 /** 32 * G_TYPE_IS_VALUE: 33 * @type: A #GType value. 34 * 35 * Checks whether the passed in type ID can be used for g_value_init(). 36 * That is, this macro checks whether this type provides an implementation 37 * of the #GTypeValueTable functions required for a type to create a #GValue of. 38 * 39 * Returns: Whether @type is suitable as a #GValue type. 40 */ 41 #define G_TYPE_IS_VALUE(type) (g_type_check_is_value_type (type)) 42 /** 43 * G_IS_VALUE: 44 * @value: A #GValue structure. 45 * 46 * Checks if @value is a valid and initialized #GValue structure. 47 * 48 * Returns: %TRUE on success. 49 */ 50 #define G_IS_VALUE(value) (G_TYPE_CHECK_VALUE (value)) 51 /** 52 * G_VALUE_TYPE: 53 * @value: A #GValue structure. 54 * 55 * Get the type identifier of @value. 56 * 57 * Returns: the #GType. 58 */ 59 #define G_VALUE_TYPE(value) (((GValue*) (value))->g_type) 60 /** 61 * G_VALUE_TYPE_NAME: 62 * @value: A #GValue structure. 63 * 64 * Gets the type name of @value. 65 * 66 * Returns: the type name. 67 */ 68 #define G_VALUE_TYPE_NAME(value) (g_type_name (G_VALUE_TYPE (value))) 69 /** 70 * G_VALUE_HOLDS: 71 * @value: A #GValue structure. 72 * @type: A #GType value. 73 * 74 * Checks if @value holds (or contains) a value of @type. 75 * This macro will also check for @value != %NULL and issue a 76 * warning if the check fails. 77 * 78 * Returns: %TRUE if @value holds the @type. 79 */ 80 #define G_VALUE_HOLDS(value,type) (G_TYPE_CHECK_VALUE_TYPE ((value), (type))) 81 82 83 /* --- typedefs & structures --- */ 84 /** 85 * GValueTransform: 86 * @src_value: Source value. 87 * @dest_value: Target value. 88 * 89 * The type of value transformation functions which can be registered with 90 * g_value_register_transform_func(). 91 * 92 * @dest_value will be initialized to the correct destination type. 93 */ 94 typedef void (*GValueTransform) (const GValue *src_value, 95 GValue *dest_value); 96 /** 97 * GValue: 98 * 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 103 * types. 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. 107 */ 108 struct _GValue 109 { 110 /*< private >*/ 111 GType g_type; 112 113 /* public for GTypeValueTable methods */ 114 union { 115 gint v_int; 116 guint v_uint; 117 glong v_long; 118 gulong v_ulong; 119 gint64 v_int64; 120 guint64 v_uint64; 121 gfloat v_float; 122 gdouble v_double; 123 gpointer v_pointer; 124 } data[2]; 125 }; 126 127 128 /* --- prototypes --- */ 129 GLIB_AVAILABLE_IN_ALL 130 GValue* g_value_init (GValue *value, 131 GType g_type); 132 GLIB_AVAILABLE_IN_ALL 133 void g_value_copy (const GValue *src_value, 134 GValue *dest_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, 141 gpointer instance); 142 GLIB_AVAILABLE_IN_2_42 143 void g_value_init_from_instance (GValue *value, 144 gpointer instance); 145 146 147 /* --- private --- */ 148 GLIB_AVAILABLE_IN_ALL 149 gboolean g_value_fits_pointer (const GValue *value); 150 GLIB_AVAILABLE_IN_ALL 151 gpointer g_value_peek_pointer (const GValue *value); 152 153 154 /* --- implementation details --- */ 155 GLIB_AVAILABLE_IN_ALL 156 gboolean g_value_type_compatible (GType src_type, 157 GType dest_type); 158 GLIB_AVAILABLE_IN_ALL 159 gboolean g_value_type_transformable (GType src_type, 160 GType dest_type); 161 GLIB_AVAILABLE_IN_ALL 162 gboolean g_value_transform (const GValue *src_value, 163 GValue *dest_value); 164 GLIB_AVAILABLE_IN_ALL 165 void g_value_register_transform_func (GType src_type, 166 GType dest_type, 167 GValueTransform transform_func); 168 169 /** 170 * G_VALUE_NOCOPY_CONTENTS: 171 * 172 * If passed to G_VALUE_COLLECT(), allocated data won't be copied 173 * but used verbatim. This does not affect ref-counted types like 174 * objects. This does not affect usage of g_value_copy(), the data will 175 * be copied if it is not ref-counted. 176 */ 177 #define G_VALUE_NOCOPY_CONTENTS (1 << 27) 178 179 /** 180 * G_VALUE_INTERNED_STRING: 181 * 182 * For string values, indicates that the string contained is canonical and will 183 * exist for the duration of the process. See g_value_set_interned_string(). 184 * 185 * Since: 2.66 186 */ 187 #define G_VALUE_INTERNED_STRING (1 << 28) GLIB_AVAILABLE_MACRO_IN_2_66 188 189 /** 190 * G_VALUE_INIT: 191 * 192 * A #GValue must be initialized before it can be used. This macro can 193 * be used as initializer instead of an explicit `{ 0 }` when declaring 194 * a variable, but it cannot be assigned to a variable. 195 * 196 * |[ 197 * GValue value = G_VALUE_INIT; 198 * ]| 199 * 200 * Since: 2.30 201 */ 202 #define G_VALUE_INIT { 0, { { 0 } } } 203 204 205 G_END_DECLS 206 207 #endif /* __G_VALUE_H__ */ 208