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 /**
  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__
  34
  35 #include <glib-object.h>
  36
  37 G_BEGIN_DECLS
  38
  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  */
  44 enum    /*< skip >*/
  45 {
  46   G_VALUE_COLLECT_INT           = 'i',
  47   G_VALUE_COLLECT_LONG          = 'l',
  48   G_VALUE_COLLECT_INT64         = 'q',
  49   G_VALUE_COLLECT_DOUBLE        = 'd',
  50   G_VALUE_COLLECT_POINTER       = 'p'
  51 };
  52
  53
  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 };
  69
  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);                                                       \
  96   _value->g_type = _value_type;         /* value_meminit() from gvalue.c */             \
  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
 128
 129
 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
 183
 184
 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)
 192
 193 G_END_DECLS
 194
 195 #endif /* __G_VALUE_COLLECTOR_H__ */