gobject/gvaluecollector.h

   1 /* GObject - GLib Type, Object, Parameter and Signal Library
   2  * Copyright (C) 1998, 1999, 2000 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
  25 #ifdef __cplusplus
  26 extern "C" {
  27 #endif /* __cplusplus */
  28
  29
  30 /* we may want to add aggregate types here some day, if requested
  31  * by users. the basic C types are covered already, everything
  32  * smaller than an int is promoted to an integer and floats are
  33  * always promoted to doubles for varargs call constructions.
  34  */
  35 enum    /*< skip >*/
  36 {
  37   G_VALUE_COLLECT_NONE,
  38   G_VALUE_COLLECT_INT,
  39   G_VALUE_COLLECT_LONG,
  40   G_VALUE_COLLECT_DOUBLE,
  41   G_VALUE_COLLECT_POINTER
  42 };
  43
  44 union _GTypeCValue
  45 {
  46   gint     v_int;
  47   glong    v_long;
  48   gdouble  v_double;
  49   gpointer v_pointer;
  50 };
  51
  52
  53 /* G_VALUE_COLLECT() collects a variable argument value
  54  * from a va_list. we have to implement the varargs collection as a
  55  * macro, because on some systems va_list variables cannot be passed
  56  * by reference.
  57  * value is supposed to be initialized according to the value
  58  * type to be collected.
  59  * var_args is the va_list variable and may be evaluated multiple times.
  60  * __error is a gchar** variable that will be modified to hold a g_new()
  61  * allocated error messages if something fails.
  62  */
  63 #define G_VALUE_COLLECT(value, var_args, __error)                                       \
  64 G_STMT_START {                                                                          \
  65   GValue *_value = (value);                                                             \
  66   GTypeValueTable *_vtable = g_type_value_table_peek (G_VALUE_TYPE (_value));           \
  67   gchar *_error_msg = NULL;                                                             \
  68   guint _collect_type = _vtable->collect_type;                                          \
  69   guint _nth_value = 0;                                                                 \
  70                                                                                         \
  71   g_value_reset (_value);                                                               \
  72   while (_collect_type && !_error_msg)                                                  \
  73     {                                                                                   \
  74       GTypeCValue _cvalue = { 0, };                                                     \
  75                                                                                         \
  76       switch (_collect_type)                                                            \
  77         {                                                                               \
  78         case G_VALUE_COLLECT_INT:                                                       \
  79           _cvalue.v_int = va_arg ((var_args), gint);                                    \
  80           break;                                                                        \
  81         case G_VALUE_COLLECT_LONG:                                                      \
  82           _cvalue.v_long = va_arg ((var_args), glong);                                  \
  83           break;                                                                        \
  84         case G_VALUE_COLLECT_DOUBLE:                                                    \
  85           _cvalue.v_double = va_arg ((var_args), gdouble);                              \
  86           break;                                                                        \
  87         case G_VALUE_COLLECT_POINTER:                                                   \
  88           _cvalue.v_pointer = va_arg ((var_args), gpointer);                            \
  89           break;                                                                        \
  90         default:                                                                        \
  91           _error_msg  = g_strdup_printf ("%s: invalid collect type (%d) used for %s",   \
  92                                          G_STRLOC,                                      \
  93                                          _collect_type,                                 \
  94                                          "G_VALUE_COLLECT()");                          \
  95           continue;                                                                     \
  96         }                                                                               \
  97       _error_msg = _vtable->collect_value (_value,                                      \
  98                                            _nth_value++,                                \
  99                                            &_collect_type,                              \
 100                                            &_cvalue);                                   \
 101     }                                                                                   \
 102   *(__error) = _error_msg;                                                              \
 103 } G_STMT_END
 104
 105
 106 /* G_VALUE_LCOPY() collects a value's variable argument
 107  * locations from a va_list. usage is analogous to G_VALUE_COLLECT().
 108  */
 109 #define G_VALUE_LCOPY(value, var_args, __error)                                         \
 110 G_STMT_START {                                                                          \
 111   GValue *_value = (value);                                                             \
 112   GTypeValueTable *_vtable = g_type_value_table_peek (G_VALUE_TYPE (_value));           \
 113   gchar *_error_msg = NULL;                                                             \
 114   guint _lcopy_type = _vtable->lcopy_type;                                              \
 115   guint _nth_value = 0;                                                                 \
 116                                                                                         \
 117   while (_lcopy_type && !_error_msg)                                                    \
 118     {                                                                                   \
 119       GTypeCValue _cvalue = { 0, };                                                     \
 120                                                                                         \
 121       switch (_lcopy_type)                                                              \
 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           _error_msg  = g_strdup_printf ("%s: invalid collect type (%d) used for %s",   \
 137                                          G_STRLOC,                                      \
 138                                          _lcopy_type,                                   \
 139                                          "G_VALUE_LCOPY()");                            \
 140           continue;                                                                     \
 141         }                                                                               \
 142       _error_msg = _vtable->lcopy_value (_value,                                        \
 143                                          _nth_value++,                                  \
 144                                          &_lcopy_type,                                  \
 145                                          &_cvalue);                                     \
 146     }                                                                                   \
 147   *(__error) = _error_msg;                                                              \
 148 } G_STMT_END
 149
 150
 151
 152 #ifdef __cplusplus
 153 }
 154 #endif /* __cplusplus */
 155
 156 #endif /* __G_VALUE_COLLECTOR_H__ */