glib/gmacros.h

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   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 Public
  15  * 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
  20 /*
  21  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  22  * file for a list of people on the GLib Team.  See the ChangeLog
  23  * files for a list of changes.  These files are distributed with
  24  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  25  */
  26
  27 /* This file must not include any other glib header file and must thus
  28  * not refer to variables from glibconfig.h
  29  */
  30
  31 #ifndef __G_MACROS_H__
  32 #define __G_MACROS_H__
  33
  34 /* We include stddef.h to get the system's definition of NULL
  35  */
  36 #include <stddef.h>
  37
  38 /* Here we provide G_GNUC_EXTENSION as an alias for __extension__,
  39  * where this is valid. This allows for warningless compilation of
  40  * "long long" types even in the presence of '-ansi -pedantic'.
  41  */
  42 #if     __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8)
  43 #  define G_GNUC_EXTENSION __extension__
  44 #else
  45 #  define G_GNUC_EXTENSION
  46 #endif
  47
  48 /* Provide macros to feature the GCC function attribute.
  49  */
  50 #if    __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
  51 #define G_GNUC_PURE                            \
  52   __attribute__((__pure__))
  53 #else
  54 #define G_GNUC_PURE
  55 #endif
  56
  57 #if     __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ > 4)
  58 #define G_GNUC_PRINTF( format_idx, arg_idx )    \
  59   __attribute__((__format__ (__printf__, format_idx, arg_idx)))
  60 #define G_GNUC_SCANF( format_idx, arg_idx )     \
  61   __attribute__((__format__ (__scanf__, format_idx, arg_idx)))
  62 #define G_GNUC_FORMAT( arg_idx )                \
  63   __attribute__((__format_arg__ (arg_idx)))
  64 #define G_GNUC_NORETURN                         \
  65   __attribute__((__noreturn__))
  66 #define G_GNUC_CONST                            \
  67   __attribute__((__const__))
  68 #define G_GNUC_UNUSED                           \
  69   __attribute__((__unused__))
  70 #define G_GNUC_NO_INSTRUMENT                    \
  71   __attribute__((__no_instrument_function__))
  72 #else   /* !__GNUC__ */
  73 #define G_GNUC_PRINTF( format_idx, arg_idx )
  74 #define G_GNUC_SCANF( format_idx, arg_idx )
  75 #define G_GNUC_FORMAT( arg_idx )
  76 #define G_GNUC_NORETURN
  77 #define G_GNUC_CONST
  78 #define G_GNUC_UNUSED
  79 #define G_GNUC_NO_INSTRUMENT
  80 #endif  /* !__GNUC__ */
  81
  82 #if    __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)
  83 #define G_GNUC_DEPRECATED                            \
  84   __attribute__((__deprecated__))
  85 #else
  86 #define G_GNUC_DEPRECATED
  87 #endif /* __GNUC__ */
  88
  89 /* Wrap the gcc __PRETTY_FUNCTION__ and __FUNCTION__ variables with
  90  * macros, so we can refer to them as strings unconditionally.
  91  */
  92 #if defined (__GNUC__) && (__GNUC__ < 3)
  93 #define G_GNUC_FUNCTION         __FUNCTION__
  94 #define G_GNUC_PRETTY_FUNCTION  __PRETTY_FUNCTION__
  95 #else   /* !__GNUC__ */
  96 #define G_GNUC_FUNCTION         ""
  97 #define G_GNUC_PRETTY_FUNCTION  ""
  98 #endif  /* !__GNUC__ */
  99
 100 #define G_STRINGIFY(macro_or_string)    G_STRINGIFY_ARG (macro_or_string)
 101 #define G_STRINGIFY_ARG(contents)       #contents
 102
 103 /* Provide a string identifying the current code position */
 104 #if defined(__GNUC__) && (__GNUC__ < 3) && !defined(__cplusplus)
 105 #  define G_STRLOC      __FILE__ ":" G_STRINGIFY (__LINE__) ":" __PRETTY_FUNCTION__ "()"
 106 #else
 107 #  define G_STRLOC      __FILE__ ":" G_STRINGIFY (__LINE__)
 108 #endif
 109
 110 /* Guard C code in headers, while including them from C++ */
 111 #ifdef  __cplusplus
 112 # define G_BEGIN_DECLS  extern "C" {
 113 # define G_END_DECLS    }
 114 #else
 115 # define G_BEGIN_DECLS
 116 # define G_END_DECLS
 117 #endif
 118
 119 /* Provide definitions for some commonly used macros.
 120  *  Some of them are only provided if they haven't already
 121  *  been defined. It is assumed that if they are already
 122  *  defined then the current definition is correct.
 123  */
 124 #ifndef NULL
 125 #  ifdef __cplusplus
 126 #    define NULL        (0L)
 127 #  else /* !__cplusplus */
 128 #    define NULL        ((void*) 0)
 129 #  endif /* !__cplusplus */
 130 #endif
 131
 132 #ifndef FALSE
 133 #define FALSE   (0)
 134 #endif
 135
 136 #ifndef TRUE
 137 #define TRUE    (!FALSE)
 138 #endif
 139
 140 #undef  MAX
 141 #define MAX(a, b)  (((a) > (b)) ? (a) : (b))
 142
 143 #undef  MIN
 144 #define MIN(a, b)  (((a) < (b)) ? (a) : (b))
 145
 146 #undef  ABS
 147 #define ABS(a)     (((a) < 0) ? -(a) : (a))
 148
 149 #undef  CLAMP
 150 #define CLAMP(x, low, high)  (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))
 151
 152 /* Count the number of elements in an array. The array must be defined
 153  * as such; using this with a dynamically allocated array will give
 154  * incorrect results.
 155  */
 156 #define G_N_ELEMENTS(arr)               (sizeof (arr) / sizeof ((arr)[0]))
 157
 158 /* Macros by analogy to GINT_TO_POINTER, GPOINTER_TO_INT
 159  */
 160 #define GPOINTER_TO_SIZE(p)     ((gsize) (p))
 161 #define GSIZE_TO_POINTER(s)     ((gpointer) (gsize) (s))
 162
 163 /* Provide convenience macros for handling structure
 164  * fields through their offsets.
 165  */
 166 #define G_STRUCT_OFFSET(struct_type, member)    \
 167     ((glong) ((guint8*) &((struct_type*) 0)->member))
 168 #define G_STRUCT_MEMBER_P(struct_p, struct_offset)   \
 169     ((gpointer) ((guint8*) (struct_p) + (glong) (struct_offset)))
 170 #define G_STRUCT_MEMBER(member_type, struct_p, struct_offset)   \
 171     (*(member_type*) G_STRUCT_MEMBER_P ((struct_p), (struct_offset)))
 172
 173 /* Provide simple macro statement wrappers (adapted from Perl):
 174  *  G_STMT_START { statements; } G_STMT_END;
 175  *  can be used as a single statement, as in
 176  *  if (x) G_STMT_START { ... } G_STMT_END; else ...
 177  *
 178  *  For gcc we will wrap the statements within `({' and `})' braces.
 179  *  For SunOS they will be wrapped within `if (1)' and `else (void) 0',
 180  *  and otherwise within `do' and `while (0)'.
 181  */
 182 #if !(defined (G_STMT_START) && defined (G_STMT_END))
 183 #  if defined (__GNUC__) && !defined (__STRICT_ANSI__) && !defined (__cplusplus)
 184 #    define G_STMT_START        (void)(
 185 #    define G_STMT_END          )
 186 #  else
 187 #    if (defined (sun) || defined (__sun__))
 188 #      define G_STMT_START      if (1)
 189 #      define G_STMT_END        else (void)0
 190 #    else
 191 #      define G_STMT_START      do
 192 #      define G_STMT_END        while (0)
 193 #    endif
 194 #  endif
 195 #endif
 196
 197 /* Allow the app programmer to select whether or not return values
 198  * (usually char*) are const or not.  Don't try using this feature for
 199  * functions with C++ linkage.
 200  */
 201 #ifdef G_DISABLE_CONST_RETURNS
 202 #define G_CONST_RETURN
 203 #else
 204 #define G_CONST_RETURN const
 205 #endif
 206
 207 /*
 208  * The G_LIKELY and G_UNLIKELY macros let the programmer give hints to
 209  * the compiler about the expected result of an expression. Some compilers
 210  * can use this information for optimizations.
 211  *
 212  * The _G_BOOLEAN_EXPR macro is intended to trigger a gcc warning when
 213  * putting assignments in g_return_if_fail ().
 214  */
 215 #if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
 216 #define _G_BOOLEAN_EXPR(expr)                   \
 217  __extension__ ({                               \
 218    int _g_boolean_var_;                         \
 219    if (expr)                                    \
 220       _g_boolean_var_ = 1;                      \
 221    else                                         \
 222       _g_boolean_var_ = 0;                      \
 223    _g_boolean_var_;                             \
 224 })
 225 #define G_LIKELY(expr) (__builtin_expect (_G_BOOLEAN_EXPR(expr), 1))
 226 #define G_UNLIKELY(expr) (__builtin_expect (_G_BOOLEAN_EXPR(expr), 0))
 227 #else
 228 #define G_LIKELY(expr) (expr)
 229 #define G_UNLIKELY(expr) (expr)
 230 #endif
 231
 232 #endif /* __G_MACROS_H__ */