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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 actuall values collected
55 */
56 /**
57 * GTypeCValue:
58 *
59 * A union holding one collected value.
60 */
61 union _GTypeCValue
62 {
63 gint v_int;
64 glong v_long;
65 gint64 v_int64;
66 gdouble v_double;
67 gpointer v_pointer;
68 };
70 /**
71 * G_VALUE_COLLECT:
72 * @value: a #GValue return location. @value is supposed to be initialized
73 * according to the value type to be collected
74 * @var_args: the va_list variable; it may be evaluated multiple times
75 * @flags: flags which are passed on to the collect_value() function of
76 * the #GTypeValueTable of @value.
77 * @__error: a #gchar** variable that will be modified to hold a g_new()
78 * allocated error messages if something fails
79 *
80 * Collects a variable argument value from a va_list. We have to
81 * implement the varargs collection as a macro, because on some systems
82 * va_list variables cannot be passed by reference.
83 */
84 #define G_VALUE_COLLECT(value, var_args, flags, __error) \
85 G_STMT_START { \
86 GValue *_value = (value); \
87 guint _flags = (flags); \
88 GType _value_type = G_VALUE_TYPE (_value); \
89 GTypeValueTable *_vtable = g_type_value_table_peek (_value_type); \
90 gchar *_collect_format = _vtable->collect_format; \
91 GTypeCValue _cvalues[G_VALUE_COLLECT_FORMAT_MAX_LENGTH] = { { 0, }, }; \
92 guint _n_values = 0; \
93 \
94 if (_vtable->value_free) \
95 _vtable->value_free (_value); \
97 memset (_value->data, 0, sizeof (_value->data)); \
98 while (*_collect_format) \
99 { \
100 GTypeCValue *_cvalue = _cvalues + _n_values++; \
101 \
102 switch (*_collect_format++) \
103 { \
104 case G_VALUE_COLLECT_INT: \
105 _cvalue->v_int = va_arg ((var_args), gint); \
106 break; \
107 case G_VALUE_COLLECT_LONG: \
108 _cvalue->v_long = va_arg ((var_args), glong); \
109 break; \
110 case G_VALUE_COLLECT_INT64: \
111 _cvalue->v_int64 = va_arg ((var_args), gint64); \
112 break; \
113 case G_VALUE_COLLECT_DOUBLE: \
114 _cvalue->v_double = va_arg ((var_args), gdouble); \
115 break; \
116 case G_VALUE_COLLECT_POINTER: \
117 _cvalue->v_pointer = va_arg ((var_args), gpointer); \
118 break; \
119 default: \
120 g_assert_not_reached (); \
121 } \
122 } \
123 *(__error) = _vtable->collect_value (_value, \
124 _n_values, \
125 _cvalues, \
126 _flags); \
127 } G_STMT_END
130 /**
131 * G_VALUE_LCOPY:
132 * @value: a #GValue return location. @value is supposed to be initialized
133 * according to the value type to be collected
134 * @var_args: the va_list variable; it may be evaluated multiple times
135 * @flags: flags which are passed on to the lcopy_value() function of
136 * the #GTypeValueTable of @value.
137 * @__error: a #gchar** variable that will be modified to hold a g_new()
138 * allocated error messages if something fails
139 *
140 * Collects a value's variable argument locations from a va_list. Usage is
141 * analogous to G_VALUE_COLLECT().
142 */
143 #define G_VALUE_LCOPY(value, var_args, flags, __error) \
144 G_STMT_START { \
145 const GValue *_value = (value); \
146 guint _flags = (flags); \
147 GType _value_type = G_VALUE_TYPE (_value); \
148 GTypeValueTable *_vtable = g_type_value_table_peek (_value_type); \
149 gchar *_lcopy_format = _vtable->lcopy_format; \
150 GTypeCValue _cvalues[G_VALUE_COLLECT_FORMAT_MAX_LENGTH] = { { 0, }, }; \
151 guint _n_values = 0; \
152 \
153 while (*_lcopy_format) \
154 { \
155 GTypeCValue *_cvalue = _cvalues + _n_values++; \
156 \
157 switch (*_lcopy_format++) \
158 { \
159 case G_VALUE_COLLECT_INT: \
160 _cvalue->v_int = va_arg ((var_args), gint); \
161 break; \
162 case G_VALUE_COLLECT_LONG: \
163 _cvalue->v_long = va_arg ((var_args), glong); \
164 break; \
165 case G_VALUE_COLLECT_INT64: \
166 _cvalue->v_int64 = va_arg ((var_args), gint64); \
167 break; \
168 case G_VALUE_COLLECT_DOUBLE: \
169 _cvalue->v_double = va_arg ((var_args), gdouble); \
170 break; \
171 case G_VALUE_COLLECT_POINTER: \
172 _cvalue->v_pointer = va_arg ((var_args), gpointer); \
173 break; \
174 default: \
175 g_assert_not_reached (); \
176 } \
177 } \
178 *(__error) = _vtable->lcopy_value (_value, \
179 _n_values, \
180 _cvalues, \
181 _flags); \
182 } G_STMT_END
185 /**
186 * G_VALUE_COLLECT_FORMAT_MAX_LENGTH:
187 *
188 * The maximal number of #GTypeCValue<!-- -->s which can be collected for a
189 * single #GValue.
190 */
191 #define G_VALUE_COLLECT_FORMAT_MAX_LENGTH (8)
193 G_END_DECLS