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 #define G_GNUC_MALLOC                           \
  54   __attribute__((__malloc__))
  55 #else
  56 #define G_GNUC_PURE
  57 #define G_GNUC_MALLOC
  58 #endif
  59
  60 #if     __GNUC__ >= 4
  61 #define G_GNUC_NULL_TERMINATED __attribute__((__sentinel__))
  62 #else
  63 #define G_GNUC_NULL_TERMINATED
  64 #endif
  65
  66 #if     __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ > 4)
  67 #define G_GNUC_PRINTF( format_idx, arg_idx )    \
  68   __attribute__((__format__ (__printf__, format_idx, arg_idx)))
  69 #define G_GNUC_SCANF( format_idx, arg_idx )     \
  70   __attribute__((__format__ (__scanf__, format_idx, arg_idx)))
  71 #define G_GNUC_FORMAT( arg_idx )                \
  72   __attribute__((__format_arg__ (arg_idx)))
  73 #define G_GNUC_NORETURN                         \
  74   __attribute__((__noreturn__))
  75 #define G_GNUC_CONST                            \
  76   __attribute__((__const__))
  77 #define G_GNUC_UNUSED                           \
  78   __attribute__((__unused__))
  79 #define G_GNUC_NO_INSTRUMENT                    \
  80   __attribute__((__no_instrument_function__))
  81 #else   /* !__GNUC__ */
  82 #define G_GNUC_PRINTF( format_idx, arg_idx )
  83 #define G_GNUC_SCANF( format_idx, arg_idx )
  84 #define G_GNUC_FORMAT( arg_idx )
  85 #define G_GNUC_NORETURN
  86 #define G_GNUC_CONST
  87 #define G_GNUC_UNUSED
  88 #define G_GNUC_NO_INSTRUMENT
  89 #endif  /* !__GNUC__ */
  90
  91 #if    __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)
  92 #define G_GNUC_DEPRECATED                            \
  93   __attribute__((__deprecated__))
  94 #else
  95 #define G_GNUC_DEPRECATED
  96 #endif /* __GNUC__ */
  97
  98 #if     __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 3)
  99 #  define G_GNUC_MAY_ALIAS __attribute__((may_alias))
 100 #else
 101 #  define G_GNUC_MAY_ALIAS
 102 #endif
 103
 104 #if    __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
 105 #define G_GNUC_WARN_UNUSED_RESULT               \
 106   __attribute__((warn_unused_result))
 107 #else
 108 #define G_GNUC_WARN_UNUSED_RESULT
 109 #endif /* __GNUC__ */
 110
 111 #ifndef G_DISABLE_DEPRECATED
 112 /* Wrap the gcc __PRETTY_FUNCTION__ and __FUNCTION__ variables with
 113  * macros, so we can refer to them as strings unconditionally.
 114  * usage not-recommended since gcc-3.0
 115  */
 116 #if defined (__GNUC__) && (__GNUC__ < 3)
 117 #define G_GNUC_FUNCTION         __FUNCTION__
 118 #define G_GNUC_PRETTY_FUNCTION  __PRETTY_FUNCTION__
 119 #else   /* !__GNUC__ */
 120 #define G_GNUC_FUNCTION         ""
 121 #define G_GNUC_PRETTY_FUNCTION  ""
 122 #endif  /* !__GNUC__ */
 123 #endif  /* !G_DISABLE_DEPRECATED */
 124
 125 #define G_STRINGIFY(macro_or_string)    G_STRINGIFY_ARG (macro_or_string)
 126 #define G_STRINGIFY_ARG(contents)       #contents
 127
 128 /* Provide a string identifying the current code position */
 129 #if defined(__GNUC__) && (__GNUC__ < 3) && !defined(__cplusplus)
 130 #  define G_STRLOC      __FILE__ ":" G_STRINGIFY (__LINE__) ":" __PRETTY_FUNCTION__ "()"
 131 #else
 132 #  define G_STRLOC      __FILE__ ":" G_STRINGIFY (__LINE__)
 133 #endif
 134
 135 /* Provide a string identifying the current function, non-concatenatable */
 136 #if defined (__GNUC__)
 137 #  define G_STRFUNC     ((const char*) (__PRETTY_FUNCTION__))
 138 #elif defined (G_HAVE_ISO_VARARGS)
 139 #  define G_STRFUNC     ((const char*) (__func__))
 140 #else
 141 #  define G_STRFUNC     ((const char*) ("???"))
 142 #endif
 143
 144 /* Guard C code in headers, while including them from C++ */
 145 #ifdef  __cplusplus
 146 # define G_BEGIN_DECLS  extern "C" {
 147 # define G_END_DECLS    }
 148 #else
 149 # define G_BEGIN_DECLS
 150 # define G_END_DECLS
 151 #endif
 152
 153 /* Provide definitions for some commonly used macros.
 154  *  Some of them are only provided if they haven't already
 155  *  been defined. It is assumed that if they are already
 156  *  defined then the current definition is correct.
 157  */
 158 #ifndef NULL
 159 #  ifdef __cplusplus
 160 #    define NULL        (0L)
 161 #  else /* !__cplusplus */
 162 #    define NULL        ((void*) 0)
 163 #  endif /* !__cplusplus */
 164 #endif
 165
 166 #ifndef FALSE
 167 #define FALSE   (0)
 168 #endif
 169
 170 #ifndef TRUE
 171 #define TRUE    (!FALSE)
 172 #endif
 173
 174 #undef  MAX
 175 #define MAX(a, b)  (((a) > (b)) ? (a) : (b))
 176
 177 #undef  MIN
 178 #define MIN(a, b)  (((a) < (b)) ? (a) : (b))
 179
 180 #undef  ABS
 181 #define ABS(a)     (((a) < 0) ? -(a) : (a))
 182
 183 #undef  CLAMP
 184 #define CLAMP(x, low, high)  (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))
 185
 186 /* Count the number of elements in an array. The array must be defined
 187  * as such; using this with a dynamically allocated array will give
 188  * incorrect results.
 189  */
 190 #define G_N_ELEMENTS(arr)               (sizeof (arr) / sizeof ((arr)[0]))
 191
 192 /* Macros by analogy to GINT_TO_POINTER, GPOINTER_TO_INT
 193  */
 194 #define GPOINTER_TO_SIZE(p)     ((gsize) (p))
 195 #define GSIZE_TO_POINTER(s)     ((gpointer) (gsize) (s))
 196
 197 /* Provide convenience macros for handling structure
 198  * fields through their offsets.
 199  */
 200 #define G_STRUCT_OFFSET(struct_type, member)    \
 201     ((glong) ((guint8*) &((struct_type*) 0)->member))
 202 #define G_STRUCT_MEMBER_P(struct_p, struct_offset)   \
 203     ((gpointer) ((guint8*) (struct_p) + (glong) (struct_offset)))
 204 #define G_STRUCT_MEMBER(member_type, struct_p, struct_offset)   \
 205     (*(member_type*) G_STRUCT_MEMBER_P ((struct_p), (struct_offset)))
 206
 207 /* Provide simple macro statement wrappers (adapted from Perl):
 208  *  G_STMT_START { statements; } G_STMT_END;
 209  *  can be used as a single statement, as in
 210  *  if (x) G_STMT_START { ... } G_STMT_END; else ...
 211  *
 212  *  When GCC is compiling C code in non-ANSI mode, it will use the
 213  *  compiler __extension__ to wrap the statements wihin `({' and '})' braces.
 214  *  When compiling on platforms where configure has defined
 215  *  HAVE_DOWHILE_MACROS, statements will be wrapped with `do' and `while (0)'.
 216  *  For any other platforms (SunOS4 is known to have this issue), wrap the
 217  *  statements with `if (1)' and `else (void) 0'.
 218  */
 219 #if !(defined (G_STMT_START) && defined (G_STMT_END))
 220 # if defined (__GNUC__) && !defined (__STRICT_ANSI__) && !defined (__cplusplus)
 221 #  define G_STMT_START (void) __extension__ (
 222 #  define G_STMT_END )
 223 # else /* !(__GNUC__ && !__STRICT_ANSI__ && !__cplusplus) */
 224 #  if defined (HAVE_DOWHILE_MACROS)
 225 #   define G_STMT_START do
 226 #   define G_STMT_END while (0)
 227 #  else /* !HAVE_DOWHILE_MACROS */
 228 #   define G_STMT_START if (1)
 229 #   define G_STMT_END else (void) 0
 230 #  endif /* !HAVE_DOWHILE_MACROS */
 231 # endif /* !(__GNUC__ && !__STRICT_ANSI__ && !__cplusplus) */
 232 #endif
 233
 234 /* Allow the app programmer to select whether or not return values
 235  * (usually char*) are const or not.  Don't try using this feature for
 236  * functions with C++ linkage.
 237  */
 238 #ifdef G_DISABLE_CONST_RETURNS
 239 #define G_CONST_RETURN
 240 #else
 241 #define G_CONST_RETURN const
 242 #endif
 243
 244 /*
 245  * The G_LIKELY and G_UNLIKELY macros let the programmer give hints to
 246  * the compiler about the expected result of an expression. Some compilers
 247  * can use this information for optimizations.
 248  *
 249  * The _G_BOOLEAN_EXPR macro is intended to trigger a gcc warning when
 250  * putting assignments in g_return_if_fail ().
 251  */
 252 #if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
 253 #define _G_BOOLEAN_EXPR(expr)                   \
 254  __extension__ ({                               \
 255    int _g_boolean_var_;                         \
 256    if (expr)                                    \
 257       _g_boolean_var_ = 1;                      \
 258    else                                         \
 259       _g_boolean_var_ = 0;                      \
 260    _g_boolean_var_;                             \
 261 })
 262 #define G_LIKELY(expr) (__builtin_expect (_G_BOOLEAN_EXPR(expr), 1))
 263 #define G_UNLIKELY(expr) (__builtin_expect (_G_BOOLEAN_EXPR(expr), 0))
 264 #else
 265 #define G_LIKELY(expr) (expr)
 266 #define G_UNLIKELY(expr) (expr)
 267 #endif
 268
 269 #endif /* __G_MACROS_H__ */