gobject/gvaluecollector.h

   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 #ifndef __G_VALUE_COLLECTOR_H__
  22 #define __G_VALUE_COLLECTOR_H__
  23
  24 G_BEGIN_DECLS
  25
  26 /* we may want to add aggregate types here some day, if requested
  27  * by users. the basic C types are covered already, everything
  28  * smaller than an int is promoted to an integer and floats are
  29  * always promoted to doubles for varargs call constructions.
  30  */
  31 enum    /*< skip >*/
  32 {
  33   G_VALUE_COLLECT_INT           = 'i',
  34   G_VALUE_COLLECT_LONG          = 'l',
  35   G_VALUE_COLLECT_DOUBLE        = 'd',
  36   G_VALUE_COLLECT_POINTER       = 'p'
  37 };
  38
  39
  40 /* vararg union holding actuall values collected
  41  */
  42 union _GTypeCValue
  43 {
  44   gint     v_int;
  45   glong    v_long;
  46   gdouble  v_double;
  47   gpointer v_pointer;
  48 };
  49
  50
  51 /* G_VALUE_COLLECT() collects a variable argument value
  52  * from a va_list. we have to implement the varargs collection as a
  53  * macro, because on some systems va_list variables cannot be passed
  54  * by reference.
  55  * value is supposed to be initialized according to the value
  56  * type to be collected.
  57  * var_args is the va_list variable and may be evaluated multiple times.
  58  * __error is a gchar** variable that will be modified to hold a g_new()
  59  * allocated error messages if something fails.
  60  */
  61 #define G_VALUE_COLLECT(value, var_args, flags, __error)                                \
  62 G_STMT_START {                                                                          \
  63   GValue *_value = (value);                                                             \
  64   guint _flags = (flags);                                                               \
  65   GType _value_type = G_VALUE_TYPE (_value);                                            \
  66   GTypeValueTable *_vtable = g_type_value_table_peek (_value_type);                     \
  67   gchar *_collect_format = _vtable->collect_format;                                     \
  68   GTypeCValue _cvalues[G_VALUE_COLLECT_FORMAT_MAX_LENGTH] = { { 0, }, };                \
  69   guint _n_values = 0;                                                                  \
  70                                                                                         \
  71   if (_vtable->value_free)                                                              \
  72     _vtable->value_free (_value);                                                       \
  73   _value->g_type = _value_type;         /* value_meminit() from gvalue.c */             \
  74   memset (_value->data, 0, sizeof (_value->data));                                      \
  75   while (*_collect_format)                                                              \
  76     {                                                                                   \
  77       GTypeCValue *_cvalue = _cvalues + _n_values++;                                    \
  78                                                                                         \
  79       switch (*_collect_format++)                                                       \
  80         {                                                                               \
  81         case G_VALUE_COLLECT_INT:                                                       \
  82           _cvalue->v_int = va_arg ((var_args), gint);                                   \
  83           break;                                                                        \
  84         case G_VALUE_COLLECT_LONG:                                                      \
  85           _cvalue->v_long = va_arg ((var_args), glong);                                 \
  86           break;                                                                        \
  87         case G_VALUE_COLLECT_DOUBLE:                                                    \
  88           _cvalue->v_double = va_arg ((var_args), gdouble);                             \
  89           break;                                                                        \
  90         case G_VALUE_COLLECT_POINTER:                                                   \
  91           _cvalue->v_pointer = va_arg ((var_args), gpointer);                           \
  92           break;                                                                        \
  93         default:                                                                        \
  94           g_assert_not_reached ();                                                      \
  95         }                                                                               \
  96     }                                                                                   \
  97   *(__error) = _vtable->collect_value (_value,                                          \
  98                                        _n_values,                                       \
  99                                        _cvalues,                                        \
 100                                        _flags);                                         \
 101 } G_STMT_END
 102
 103
 104 /* G_VALUE_LCOPY() collects a value's variable argument
 105  * locations from a va_list. usage is analogous to G_VALUE_COLLECT().
 106  */
 107 #define G_VALUE_LCOPY(value, var_args, flags, __error)                                  \
 108 G_STMT_START {                                                                          \
 109   const GValue *_value = (value);                                                       \
 110   guint _flags = (flags);                                                               \
 111   GType _value_type = G_VALUE_TYPE (_value);                                            \
 112   GTypeValueTable *_vtable = g_type_value_table_peek (_value_type);                     \
 113   gchar *_lcopy_format = _vtable->lcopy_format;                                         \
 114   GTypeCValue _cvalues[G_VALUE_COLLECT_FORMAT_MAX_LENGTH] = { { 0, }, };                \
 115   guint _n_values = 0;                                                                  \
 116                                                                                         \
 117   while (*_lcopy_format)                                                                \
 118     {                                                                                   \
 119       GTypeCValue *_cvalue = _cvalues + _n_values++;                                    \
 120                                                                                         \
 121       switch (*_lcopy_format++)                                                         \
 122         {                                                                               \
 123         case G_VALUE_COLLECT_INT:                                                       \
 124           _cvalue->v_int = va_arg ((var_args), gint);                                   \
 125           break;                                                                        \
 126         case G_VALUE_COLLECT_LONG:                                                      \
 127           _cvalue->v_long = va_arg ((var_args), glong);                                 \
 128           break;                                                                        \
 129         case G_VALUE_COLLECT_DOUBLE:                                                    \
 130           _cvalue->v_double = va_arg ((var_args), gdouble);                             \
 131           break;                                                                        \
 132         case G_VALUE_COLLECT_POINTER:                                                   \
 133           _cvalue->v_pointer = va_arg ((var_args), gpointer);                           \
 134           break;                                                                        \
 135         default:                                                                        \
 136           g_assert_not_reached ();                                                      \
 137         }                                                                               \
 138     }                                                                                   \
 139   *(__error) = _vtable->lcopy_value (_value,                                            \
 140                                      _n_values,                                         \
 141                                      _cvalues,                                          \
 142                                      _flags);                                           \
 143 } G_STMT_END
 144
 145
 146 #define G_VALUE_COLLECT_FORMAT_MAX_LENGTH       (8)
 147
 148 G_END_DECLS
 149
 150 #endif /* __G_VALUE_COLLECTOR_H__ */