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  * @Title: Varargs Value Collection
  25  *
  26  * The macros in this section provide the varargs parsing support needed
  27  * in variadic GObject functions such as g_object_new() or g_object_set().
  28  * They currently support the collection of integral types, floating point
  29  * types and pointers.
  30  */
  31 #ifndef __G_VALUE_COLLECTOR_H__
  32 #define __G_VALUE_COLLECTOR_H__
  33
  34 #include <glib-object.h>
  35
  36 G_BEGIN_DECLS
  37
  38 /* we may want to add aggregate types here some day, if requested
  39  * by users. the basic C types are covered already, everything
  40  * smaller than an int is promoted to an integer and floats are
  41  * always promoted to doubles for varargs call constructions.
  42  */
  43 enum    /*< skip >*/
  44 {
  45   G_VALUE_COLLECT_INT           = 'i',
  46   G_VALUE_COLLECT_LONG          = 'l',
  47   G_VALUE_COLLECT_INT64         = 'q',
  48   G_VALUE_COLLECT_DOUBLE        = 'd',
  49   G_VALUE_COLLECT_POINTER       = 'p'
  50 };
  51
  52
  53 /* vararg union holding actual values collected
  54  */
  55 /**
  56  * GTypeCValue:
  57  * @v_int: the field for holding integer values
  58  * @v_long: the field for holding long integer values
  59  * @v_int64: the field for holding 64 bit integer values
  60  * @v_double: the field for holding floating point values
  61  * @v_pointer: the field for holding pointers
  62  *
  63  * A union holding one collected value.
  64  */
  65 union _GTypeCValue
  66 {
  67   gint     v_int;
  68   glong    v_long;
  69   gint64   v_int64;
  70   gdouble  v_double;
  71   gpointer v_pointer;
  72 };
  73
  74 /**
  75  * G_VALUE_COLLECT_INIT:
  76  * @value: a #GValue return location. @value must contain only 0 bytes.
  77  * @_value_type: the #GType to use for @value.
  78  * @var_args: the va_list variable; it may be evaluated multiple times
  79  * @flags: flags which are passed on to the collect_value() function of
  80  *  the #GTypeValueTable of @value.
  81  * @__error: a #gchar** variable that will be modified to hold a g_new()
  82  *  allocated error messages if something fails
  83  *
  84  * Collects a variable argument value from a va_list. We have to
  85  * implement the varargs collection as a macro, because on some systems
  86  * va_list variables cannot be passed by reference.
  87  *
  88  * Since: 2.24
  89  */
  90 #define G_VALUE_COLLECT_INIT(value, _value_type, var_args, flags, __error)              \
  91 G_STMT_START {                                                                          \
  92   GValue *_val = (value);                                                               \
  93   guint _flags = (flags);                                                               \
  94   GTypeValueTable *_vtab = g_type_value_table_peek (_value_type);                       \
  95   gchar *_collect_format = _vtab->collect_format;                                       \
  96   GTypeCValue _cvalues[G_VALUE_COLLECT_FORMAT_MAX_LENGTH] = { { 0, }, };                \
  97   guint _n_values = 0;                                                                  \
  98                                                                                         \
  99   _val->g_type = _value_type;           /* value_meminit() from gvalue.c */             \
 100   while (*_collect_format)                                                              \
 101     {                                                                                   \
 102       GTypeCValue *_cvalue = _cvalues + _n_values++;                                    \
 103                                                                                         \
 104       switch (*_collect_format++)                                                       \
 105         {                                                                               \
 106         case G_VALUE_COLLECT_INT:                                                       \
 107           _cvalue->v_int = va_arg ((var_args), gint);                                   \
 108           break;                                                                        \
 109         case G_VALUE_COLLECT_LONG:                                                      \
 110           _cvalue->v_long = va_arg ((var_args), glong);                                 \
 111           break;                                                                        \
 112         case G_VALUE_COLLECT_INT64:                                                     \
 113           _cvalue->v_int64 = va_arg ((var_args), gint64);                               \
 114           break;                                                                        \
 115         case G_VALUE_COLLECT_DOUBLE:                                                    \
 116           _cvalue->v_double = va_arg ((var_args), gdouble);                             \
 117           break;                                                                        \
 118         case G_VALUE_COLLECT_POINTER:                                                   \
 119           _cvalue->v_pointer = va_arg ((var_args), gpointer);                           \
 120           break;                                                                        \
 121         default:                                                                        \
 122           g_assert_not_reached ();                                                      \
 123         }                                                                               \
 124     }                                                                                   \
 125   *(__error) = _vtab->collect_value (_val,                                              \
 126                                        _n_values,                                       \
 127                                        _cvalues,                                        \
 128                                        _flags);                                         \
 129 } G_STMT_END
 130
 131 /**
 132  * G_VALUE_COLLECT:
 133  * @value: a #GValue return location. @value is supposed to be initialized
 134  *  according to the value type to be collected
 135  * @var_args: the va_list variable; it may be evaluated multiple times
 136  * @flags: flags which are passed on to the collect_value() function of
 137  *  the #GTypeValueTable of @value.
 138  * @__error: a #gchar** variable that will be modified to hold a g_new()
 139  *  allocated error messages if something fails
 140  *
 141  * Collects a variable argument value from a va_list. We have to
 142  * implement the varargs collection as a macro, because on some systems
 143  * va_list variables cannot be passed by reference.
 144  *
 145  * Note: If you are creating the @value argument just before calling this macro,
 146  * you should use the #G_VALUE_COLLECT_INIT variant and pass the unitialized
 147  * #GValue. That variant is faster than #G_VALUE_COLLECT.
 148  */
 149 #define G_VALUE_COLLECT(value, var_args, flags, __error) G_STMT_START {                 \
 150   GValue *_value = (value);                                                             \
 151   GType _value_type = G_VALUE_TYPE (_value);                                            \
 152   GTypeValueTable *_vtable = g_type_value_table_peek (_value_type);                     \
 153                                                                                         \
 154   if (_vtable->value_free)                                                              \
 155     _vtable->value_free (_value);                                                       \
 156   memset (_value->data, 0, sizeof (_value->data));                                      \
 157                                                                                         \
 158   G_VALUE_COLLECT_INIT(value, _value_type, var_args, flags, __error);                   \
 159 } G_STMT_END
 160
 161 #define G_VALUE_COLLECT_SKIP(_value_type, var_args)                                     \
 162 G_STMT_START {                                                                          \
 163   GTypeValueTable *_vtable = g_type_value_table_peek (_value_type);                     \
 164   gchar *_collect_format = _vtable->collect_format;                                     \
 165                                                                                         \
 166   while (*_collect_format)                                                              \
 167     {                                                                                   \
 168       switch (*_collect_format++)                                                       \
 169         {                                                                               \
 170         case G_VALUE_COLLECT_INT:                                                       \
 171           va_arg ((var_args), gint);                                                    \
 172           break;                                                                        \
 173         case G_VALUE_COLLECT_LONG:                                                      \
 174           va_arg ((var_args), glong);                                                   \
 175           break;                                                                        \
 176         case G_VALUE_COLLECT_INT64:                                                     \
 177           va_arg ((var_args), gint64);                                                  \
 178           break;                                                                        \
 179         case G_VALUE_COLLECT_DOUBLE:                                                    \
 180           va_arg ((var_args), gdouble);                                                 \
 181           break;                                                                        \
 182         case G_VALUE_COLLECT_POINTER:                                                   \
 183           va_arg ((var_args), gpointer);                                                \
 184           break;                                                                        \
 185         default:                                                                        \
 186           g_assert_not_reached ();                                                      \
 187         }                                                                               \
 188     }                                                                                   \
 189 } G_STMT_END
 190
 191 /**
 192  * G_VALUE_LCOPY:
 193  * @value: a #GValue return location. @value is supposed to be initialized
 194  *  according to the value type to be collected
 195  * @var_args: the va_list variable; it may be evaluated multiple times
 196  * @flags: flags which are passed on to the lcopy_value() function of
 197  *  the #GTypeValueTable of @value.
 198  * @__error: a #gchar** variable that will be modified to hold a g_new()
 199  *  allocated error messages if something fails
 200  *
 201  * Collects a value's variable argument locations from a va_list. Usage is
 202  * analogous to G_VALUE_COLLECT().
 203  */
 204 #define G_VALUE_LCOPY(value, var_args, flags, __error)                                  \
 205 G_STMT_START {                                                                          \
 206   const GValue *_value = (value);                                                       \
 207   guint _flags = (flags);                                                               \
 208   GType _value_type = G_VALUE_TYPE (_value);                                            \
 209   GTypeValueTable *_vtable = g_type_value_table_peek (_value_type);                     \
 210   gchar *_lcopy_format = _vtable->lcopy_format;                                         \
 211   GTypeCValue _cvalues[G_VALUE_COLLECT_FORMAT_MAX_LENGTH] = { { 0, }, };                \
 212   guint _n_values = 0;                                                                  \
 213                                                                                         \
 214   while (*_lcopy_format)                                                                \
 215     {                                                                                   \
 216       GTypeCValue *_cvalue = _cvalues + _n_values++;                                    \
 217                                                                                         \
 218       switch (*_lcopy_format++)                                                         \
 219         {                                                                               \
 220         case G_VALUE_COLLECT_INT:                                                       \
 221           _cvalue->v_int = va_arg ((var_args), gint);                                   \
 222           break;                                                                        \
 223         case G_VALUE_COLLECT_LONG:                                                      \
 224           _cvalue->v_long = va_arg ((var_args), glong);                                 \
 225           break;                                                                        \
 226         case G_VALUE_COLLECT_INT64:                                                     \
 227           _cvalue->v_int64 = va_arg ((var_args), gint64);                               \
 228           break;                                                                        \
 229         case G_VALUE_COLLECT_DOUBLE:                                                    \
 230           _cvalue->v_double = va_arg ((var_args), gdouble);                             \
 231           break;                                                                        \
 232         case G_VALUE_COLLECT_POINTER:                                                   \
 233           _cvalue->v_pointer = va_arg ((var_args), gpointer);                           \
 234           break;                                                                        \
 235         default:                                                                        \
 236           g_assert_not_reached ();                                                      \
 237         }                                                                               \
 238     }                                                                                   \
 239   *(__error) = _vtable->lcopy_value (_value,                                            \
 240                                      _n_values,                                         \
 241                                      _cvalues,                                          \
 242                                      _flags);                                           \
 243 } G_STMT_END
 244
 245
 246 /**
 247  * G_VALUE_COLLECT_FORMAT_MAX_LENGTH:
 248  *
 249  * The maximal number of #GTypeCValue<!-- -->s which can be collected for a
 250  * single #GValue.
 251  */
 252 #define G_VALUE_COLLECT_FORMAT_MAX_LENGTH       (8)
 253
 254 G_END_DECLS
 255
 256 #endif /* __G_VALUE_COLLECTOR_H__ */