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1 /* GObject - GLib Type, Object, Parameter and Signal Library
2 * Copyright (C) 1998-1999, 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 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, write to the
16 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
17 * Boston, MA 02111-1307, USA.
18 *
19 * gvaluecollector.h: GValue varargs stubs
20 */
21 /**
22 * SECTION:value_collection
23 * @Short_description: Converting varargs to generic values
24 * @See_also:#GValueTable
25 * @Title: Varargs Value Collection
26 *
27 * The macros in this section provide the varargs parsing support needed
28 * in variadic GObject functions such as g_object_new() or g_object_set().
29 * They currently support the collection of integral types, floating point
30 * types and pointers.
31 */
32 #ifndef __G_VALUE_COLLECTOR_H__
33 #define __G_VALUE_COLLECTOR_H__
35 #include <glib-object.h>
37 G_BEGIN_DECLS
39 /* we may want to add aggregate types here some day, if requested
40 * by users. the basic C types are covered already, everything
41 * smaller than an int is promoted to an integer and floats are
42 * always promoted to doubles for varargs call constructions.
43 */
45 {
51 };
54 /* vararg union holding actual values collected
55 */
56 /**
57 * GTypeCValue:
58 * @v_int: the field for holding integer values
59 * @v_long: the field for holding long integer values
60 * @v_int64: the field for holding 64 bit integer values
61 * @v_double: the field for holding floating point values
62 * @v_pointer: the field for holding pointers
63 *
64 * A union holding one collected value.
65 */
66 union _GTypeCValue
67 {
68 gint v_int;
69 glong v_long;
70 gint64 v_int64;
71 gdouble v_double;
72 gpointer v_pointer;
73 };
75 /**
76 * G_VALUE_COLLECT_INIT:
77 * @value: a #GValue return location. @value must contain only 0 bytes.
78 * @_value_type: the #GType to use for @value.
79 * @var_args: the va_list variable; it may be evaluated multiple times
80 * @flags: flags which are passed on to the collect_value() function of
81 * the #GTypeValueTable of @value.
82 * @__error: a #gchar** variable that will be modified to hold a g_new()
83 * allocated error messages if something fails
84 *
85 * Collects a variable argument value from a va_list. We have to
86 * implement the varargs collection as a macro, because on some systems
87 * va_list variables cannot be passed by reference.
88 *
89 * Since: 2.24
90 */
91 #define G_VALUE_COLLECT_INIT(value, _value_type, var_args, flags, __error) \
92 G_STMT_START { \
93 GValue *_val = (value); \
94 guint _flags = (flags); \
95 GTypeValueTable *_vtab = g_type_value_table_peek (_value_type); \
96 gchar *_collect_format = _vtab->collect_format; \
97 GTypeCValue _cvalues[G_VALUE_COLLECT_FORMAT_MAX_LENGTH] = { { 0, }, }; \
98 guint _n_values = 0; \
99 \
101 while (*_collect_format) \
102 { \
103 GTypeCValue *_cvalue = _cvalues + _n_values++; \
104 \
105 switch (*_collect_format++) \
106 { \
107 case G_VALUE_COLLECT_INT: \
108 _cvalue->v_int = va_arg ((var_args), gint); \
109 break; \
110 case G_VALUE_COLLECT_LONG: \
111 _cvalue->v_long = va_arg ((var_args), glong); \
112 break; \
113 case G_VALUE_COLLECT_INT64: \
114 _cvalue->v_int64 = va_arg ((var_args), gint64); \
115 break; \
116 case G_VALUE_COLLECT_DOUBLE: \
117 _cvalue->v_double = va_arg ((var_args), gdouble); \
118 break; \
119 case G_VALUE_COLLECT_POINTER: \
120 _cvalue->v_pointer = va_arg ((var_args), gpointer); \
121 break; \
122 default: \
123 g_assert_not_reached (); \
124 } \
125 } \
126 *(__error) = _vtab->collect_value (_val, \
127 _n_values, \
128 _cvalues, \
129 _flags); \
130 } G_STMT_END
132 /**
133 * G_VALUE_COLLECT:
134 * @value: a #GValue return location. @value is supposed to be initialized
135 * according to the value type to be collected
136 * @var_args: the va_list variable; it may be evaluated multiple times
137 * @flags: flags which are passed on to the collect_value() function of
138 * the #GTypeValueTable of @value.
139 * @__error: a #gchar** variable that will be modified to hold a g_new()
140 * allocated error messages if something fails
141 *
142 * Collects a variable argument value from a va_list. We have to
143 * implement the varargs collection as a macro, because on some systems
144 * va_list variables cannot be passed by reference.
145 *
146 * Note: If you are creating the @value argument just before calling this macro,
147 * you should use the #G_VALUE_COLLECT_INIT variant and pass the unitialized
148 * #GValue. That variant is faster than #G_VALUE_COLLECT.
149 */
150 #define G_VALUE_COLLECT(value, var_args, flags, __error) G_STMT_START { \
151 GValue *_value = (value); \
152 GType _value_type = G_VALUE_TYPE (_value); \
153 GTypeValueTable *_vtable = g_type_value_table_peek (_value_type); \
154 \
155 if (_vtable->value_free) \
156 _vtable->value_free (_value); \
157 memset (_value->data, 0, sizeof (_value->data)); \
158 \
159 G_VALUE_COLLECT_INIT(value, _value_type, var_args, flags, __error); \
160 } G_STMT_END
162 /**
163 * G_VALUE_LCOPY:
164 * @value: a #GValue return location. @value is supposed to be initialized
165 * according to the value type to be collected
166 * @var_args: the va_list variable; it may be evaluated multiple times
167 * @flags: flags which are passed on to the lcopy_value() function of
168 * the #GTypeValueTable of @value.
169 * @__error: a #gchar** variable that will be modified to hold a g_new()
170 * allocated error messages if something fails
171 *
172 * Collects a value's variable argument locations from a va_list. Usage is
173 * analogous to G_VALUE_COLLECT().
174 */
175 #define G_VALUE_LCOPY(value, var_args, flags, __error) \
176 G_STMT_START { \
177 const GValue *_value = (value); \
178 guint _flags = (flags); \
179 GType _value_type = G_VALUE_TYPE (_value); \
180 GTypeValueTable *_vtable = g_type_value_table_peek (_value_type); \
181 gchar *_lcopy_format = _vtable->lcopy_format; \
182 GTypeCValue _cvalues[G_VALUE_COLLECT_FORMAT_MAX_LENGTH] = { { 0, }, }; \
183 guint _n_values = 0; \
184 \
185 while (*_lcopy_format) \
186 { \
187 GTypeCValue *_cvalue = _cvalues + _n_values++; \
188 \
189 switch (*_lcopy_format++) \
190 { \
191 case G_VALUE_COLLECT_INT: \
192 _cvalue->v_int = va_arg ((var_args), gint); \
193 break; \
194 case G_VALUE_COLLECT_LONG: \
195 _cvalue->v_long = va_arg ((var_args), glong); \
196 break; \
197 case G_VALUE_COLLECT_INT64: \
198 _cvalue->v_int64 = va_arg ((var_args), gint64); \
199 break; \
200 case G_VALUE_COLLECT_DOUBLE: \
201 _cvalue->v_double = va_arg ((var_args), gdouble); \
202 break; \
203 case G_VALUE_COLLECT_POINTER: \
204 _cvalue->v_pointer = va_arg ((var_args), gpointer); \
205 break; \
206 default: \
207 g_assert_not_reached (); \
208 } \
209 } \
210 *(__error) = _vtable->lcopy_value (_value, \
211 _n_values, \
212 _cvalues, \
213 _flags); \
214 } G_STMT_END
217 /**
218 * G_VALUE_COLLECT_FORMAT_MAX_LENGTH:
219 *
220 * The maximal number of #GTypeCValue<!-- -->s which can be collected for a
221 * single #GValue.
222 */
223 #define G_VALUE_COLLECT_FORMAT_MAX_LENGTH (8)
225 G_END_DECLS