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 #if defined(G_DISABLE_SINGLE_INCLUDES) && !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)
  32 #error "Only <glib.h> can be included directly."
  33 #endif
  34
  35 #ifndef __G_MACROS_H__
  36 #define __G_MACROS_H__
  37
  38 /* We include stddef.h to get the system's definition of NULL
  39  */
  40 #include <stddef.h>
  41
  42 /* Here we provide G_GNUC_EXTENSION as an alias for __extension__,
  43  * where this is valid. This allows for warningless compilation of
  44  * "long long" types even in the presence of '-ansi -pedantic'.
  45  */
  46 #if     __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8)
  47 #  define G_GNUC_EXTENSION __extension__
  48 #else
  49 #  define G_GNUC_EXTENSION
  50 #endif
  51
  52 /* Provide macros to feature the GCC function attribute.
  53  */
  54 #if    __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
  55 #define G_GNUC_PURE                            \
  56   __attribute__((__pure__))
  57 #define G_GNUC_MALLOC                           \
  58   __attribute__((__malloc__))
  59 #else
  60 #define G_GNUC_PURE
  61 #define G_GNUC_MALLOC
  62 #endif
  63
  64 #if     __GNUC__ >= 4
  65 #define G_GNUC_NULL_TERMINATED __attribute__((__sentinel__))
  66 #else
  67 #define G_GNUC_NULL_TERMINATED
  68 #endif
  69
  70 #if     (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
  71 #define G_GNUC_ALLOC_SIZE(x) __attribute__((__alloc_size__(x)))
  72 #define G_GNUC_ALLOC_SIZE2(x,y) __attribute__((__alloc_size__(x,y)))
  73 #else
  74 #define G_GNUC_ALLOC_SIZE(x)
  75 #define G_GNUC_ALLOC_SIZE2(x,y)
  76 #endif
  77
  78 #if     __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ > 4)
  79 #define G_GNUC_PRINTF( format_idx, arg_idx )    \
  80   __attribute__((__format__ (__printf__, format_idx, arg_idx)))
  81 #define G_GNUC_SCANF( format_idx, arg_idx )     \
  82   __attribute__((__format__ (__scanf__, format_idx, arg_idx)))
  83 #define G_GNUC_FORMAT( arg_idx )                \
  84   __attribute__((__format_arg__ (arg_idx)))
  85 #define G_GNUC_NORETURN                         \
  86   __attribute__((__noreturn__))
  87 #define G_GNUC_CONST                            \
  88   __attribute__((__const__))
  89 #define G_GNUC_UNUSED                           \
  90   __attribute__((__unused__))
  91 #define G_GNUC_NO_INSTRUMENT                    \
  92   __attribute__((__no_instrument_function__))
  93 #else   /* !__GNUC__ */
  94 #define G_GNUC_PRINTF( format_idx, arg_idx )
  95 #define G_GNUC_SCANF( format_idx, arg_idx )
  96 #define G_GNUC_FORMAT( arg_idx )
  97 #define G_GNUC_NORETURN
  98 #define G_GNUC_CONST
  99 #define G_GNUC_UNUSED
 100 #define G_GNUC_NO_INSTRUMENT
 101 #endif  /* !__GNUC__ */
 102
 103 #if    __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)
 104 #define G_GNUC_DEPRECATED                            \
 105   __attribute__((__deprecated__))
 106 #else
 107 #define G_GNUC_DEPRECATED
 108 #endif /* __GNUC__ */
 109
 110 #if    __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
 111 #define G_GNUC_DEPRECATED_FOR(f)                        \
 112   __attribute__((deprecated("Use " #f " instead")))
 113 #else
 114 #define G_GNUC_DEPRECATED_FOR(f)        G_GNUC_DEPRECATED
 115 #endif /* __GNUC__ */
 116
 117 #if     __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 3)
 118 #  define G_GNUC_MAY_ALIAS __attribute__((may_alias))
 119 #else
 120 #  define G_GNUC_MAY_ALIAS
 121 #endif
 122
 123 #if    __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
 124 #define G_GNUC_WARN_UNUSED_RESULT               \
 125   __attribute__((warn_unused_result))
 126 #else
 127 #define G_GNUC_WARN_UNUSED_RESULT
 128 #endif /* __GNUC__ */
 129
 130 #ifndef G_DISABLE_DEPRECATED
 131 /* Wrap the gcc __PRETTY_FUNCTION__ and __FUNCTION__ variables with
 132  * macros, so we can refer to them as strings unconditionally.
 133  * usage not-recommended since gcc-3.0
 134  */
 135 #if defined (__GNUC__) && (__GNUC__ < 3)
 136 #define G_GNUC_FUNCTION         __FUNCTION__
 137 #define G_GNUC_PRETTY_FUNCTION  __PRETTY_FUNCTION__
 138 #else   /* !__GNUC__ */
 139 #define G_GNUC_FUNCTION         ""
 140 #define G_GNUC_PRETTY_FUNCTION  ""
 141 #endif  /* !__GNUC__ */
 142 #endif  /* !G_DISABLE_DEPRECATED */
 143
 144 #define G_STRINGIFY(macro_or_string)    G_STRINGIFY_ARG (macro_or_string)
 145 #define G_STRINGIFY_ARG(contents)       #contents
 146
 147 #define G_PASTE_ARGS(identifier1,identifier2) identifier1 ## identifier2
 148 #define G_PASTE(identifier1,identifier2)      G_PASTE_ARGS (identifier1, identifier2)
 149 #define G_STATIC_ASSERT(expr) typedef struct { char Compile_Time_Assertion[(expr) ? 1 : -1]; } G_PASTE (_GStaticAssert_, __LINE__)
 150
 151 /* Provide a string identifying the current code position */
 152 #if defined(__GNUC__) && (__GNUC__ < 3) && !defined(__cplusplus)
 153 #  define G_STRLOC      __FILE__ ":" G_STRINGIFY (__LINE__) ":" __PRETTY_FUNCTION__ "()"
 154 #else
 155 #  define G_STRLOC      __FILE__ ":" G_STRINGIFY (__LINE__)
 156 #endif
 157
 158 /* Provide a string identifying the current function, non-concatenatable */
 159 #if defined (__GNUC__)
 160 #  define G_STRFUNC     ((const char*) (__PRETTY_FUNCTION__))
 161 #elif defined (__STDC_VERSION__) && __STDC_VERSION__ >= 19901L
 162 #  define G_STRFUNC     ((const char*) (__func__))
 163 #else
 164 #  define G_STRFUNC     ((const char*) ("???"))
 165 #endif
 166
 167 /* Guard C code in headers, while including them from C++ */
 168 #ifdef  __cplusplus
 169 # define G_BEGIN_DECLS  extern "C" {
 170 # define G_END_DECLS    }
 171 #else
 172 # define G_BEGIN_DECLS
 173 # define G_END_DECLS
 174 #endif
 175
 176 /* Provide definitions for some commonly used macros.
 177  *  Some of them are only provided if they haven't already
 178  *  been defined. It is assumed that if they are already
 179  *  defined then the current definition is correct.
 180  */
 181 #ifndef NULL
 182 #  ifdef __cplusplus
 183 #    define NULL        (0L)
 184 #  else /* !__cplusplus */
 185 #    define NULL        ((void*) 0)
 186 #  endif /* !__cplusplus */
 187 #endif
 188
 189 #ifndef FALSE
 190 #define FALSE   (0)
 191 #endif
 192
 193 #ifndef TRUE
 194 #define TRUE    (!FALSE)
 195 #endif
 196
 197 #undef  MAX
 198 #define MAX(a, b)  (((a) > (b)) ? (a) : (b))
 199
 200 #undef  MIN
 201 #define MIN(a, b)  (((a) < (b)) ? (a) : (b))
 202
 203 #undef  ABS
 204 #define ABS(a)     (((a) < 0) ? -(a) : (a))
 205
 206 #undef  CLAMP
 207 #define CLAMP(x, low, high)  (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))
 208
 209 /* Count the number of elements in an array. The array must be defined
 210  * as such; using this with a dynamically allocated array will give
 211  * incorrect results.
 212  */
 213 #define G_N_ELEMENTS(arr)               (sizeof (arr) / sizeof ((arr)[0]))
 214
 215 /* Macros by analogy to GINT_TO_POINTER, GPOINTER_TO_INT
 216  */
 217 #define GPOINTER_TO_SIZE(p)     ((gsize) (p))
 218 #define GSIZE_TO_POINTER(s)     ((gpointer) (gsize) (s))
 219
 220 /* Provide convenience macros for handling structure
 221  * fields through their offsets.
 222  */
 223
 224 #if defined(__GNUC__)  && __GNUC__ >= 4
 225 #  define G_STRUCT_OFFSET(struct_type, member) \
 226       ((glong) offsetof (struct_type, member))
 227 #else
 228 #  define G_STRUCT_OFFSET(struct_type, member)  \
 229       ((glong) ((guint8*) &((struct_type*) 0)->member))
 230 #endif
 231
 232 #define G_STRUCT_MEMBER_P(struct_p, struct_offset)   \
 233     ((gpointer) ((guint8*) (struct_p) + (glong) (struct_offset)))
 234 #define G_STRUCT_MEMBER(member_type, struct_p, struct_offset)   \
 235     (*(member_type*) G_STRUCT_MEMBER_P ((struct_p), (struct_offset)))
 236
 237 /* Provide simple macro statement wrappers:
 238  *   G_STMT_START { statements; } G_STMT_END;
 239  * This can be used as a single statement, like:
 240  *   if (x) G_STMT_START { ... } G_STMT_END; else ...
 241  * This intentionally does not use compiler extensions like GCC's '({...})' to
 242  * avoid portability issue or side effects when compiled with different compilers.
 243  */
 244 #if !(defined (G_STMT_START) && defined (G_STMT_END))
 245 #  define G_STMT_START  do
 246 #  define G_STMT_END    while (0)
 247 #endif
 248
 249 /* Allow the app programmer to select whether or not return values
 250  * (usually char*) are const or not.  Don't try using this feature for
 251  * functions with C++ linkage.
 252  */
 253 #ifdef G_DISABLE_CONST_RETURNS
 254 #define G_CONST_RETURN
 255 #else
 256 #define G_CONST_RETURN const
 257 #endif
 258
 259 /*
 260  * The G_LIKELY and G_UNLIKELY macros let the programmer give hints to
 261  * the compiler about the expected result of an expression. Some compilers
 262  * can use this information for optimizations.
 263  *
 264  * The _G_BOOLEAN_EXPR macro is intended to trigger a gcc warning when
 265  * putting assignments in g_return_if_fail ().
 266  */
 267 #if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
 268 #define _G_BOOLEAN_EXPR(expr)                   \
 269  __extension__ ({                               \
 270    int _g_boolean_var_;                         \
 271    if (expr)                                    \
 272       _g_boolean_var_ = 1;                      \
 273    else                                         \
 274       _g_boolean_var_ = 0;                      \
 275    _g_boolean_var_;                             \
 276 })
 277 #define G_LIKELY(expr) (__builtin_expect (_G_BOOLEAN_EXPR(expr), 1))
 278 #define G_UNLIKELY(expr) (__builtin_expect (_G_BOOLEAN_EXPR(expr), 0))
 279 #else
 280 #define G_LIKELY(expr) (expr)
 281 #define G_UNLIKELY(expr) (expr)
 282 #endif
 283
 284 #endif /* __G_MACROS_H__ */