include/symcat.h

   1 /* Symbol concatenation utilities.
   2
   3    Copyright (C) 1998, 2000 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License along
  16    with this program; if not, write to the Free Software Foundation, Inc.,
  17    51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 #ifndef SYM_CAT_H
  20 #define SYM_CAT_H
  21
  22 #if defined (__STDC__) || defined (ALMOST_STDC) || defined (HAVE_STRINGIZE)
  23 #define CONCAT2(a,b)     a##b
  24 #define CONCAT3(a,b,c)   a##b##c
  25 #define CONCAT4(a,b,c,d) a##b##c##d
  26 #define STRINGX(s) #s
  27 #else
  28 /* Note one should never pass extra whitespace to the CONCATn macros,
  29    e.g. CONCAT2(foo, bar) because traditonal C will keep the space between
  30    the two labels instead of concatenating them.  Instead, make sure to
  31    write CONCAT2(foo,bar).  */
  32 #define CONCAT2(a,b)     a/**/b
  33 #define CONCAT3(a,b,c)   a/**/b/**/c
  34 #define CONCAT4(a,b,c,d) a/**/b/**/c/**/d
  35 #define STRINGX(s) "s"
  36 #endif
  37
  38 #define XCONCAT2(a,b)     CONCAT2(a,b)
  39 #define XCONCAT3(a,b,c)   CONCAT3(a,b,c)
  40 #define XCONCAT4(a,b,c,d) CONCAT4(a,b,c,d)
  41
  42 /* Note the layer of indirection here is typically used to allow
  43    stringification of the expansion of macros.  I.e. "#define foo
  44    bar", "XSTRING(foo)", to yield "bar".  Be aware that this only
  45    works for __STDC__, not for traditional C which will still resolve
  46    to "foo".  */
  47 #define XSTRING(s) STRINGX(s)
  48
  49 #endif /* SYM_CAT_H */