glib/pcre/pcre_version.c

   1 /*************************************************
   2 *      Perl-Compatible Regular Expressions       *
   3 *************************************************/
   4
   5 /* PCRE is a library of functions to support regular expressions whose syntax
   6 and semantics are as close as possible to those of the Perl 5 language.
   7
   8                        Written by Philip Hazel
   9            Copyright (c) 1997-2012 University of Cambridge
  10
  11 -----------------------------------------------------------------------------
  12 Redistribution and use in source and binary forms, with or without
  13 modification, are permitted provided that the following conditions are met:
  14
  15     * Redistributions of source code must retain the above copyright notice,
  16       this list of conditions and the following disclaimer.
  17
  18     * Redistributions in binary form must reproduce the above copyright
  19       notice, this list of conditions and the following disclaimer in the
  20       documentation and/or other materials provided with the distribution.
  21
  22     * Neither the name of the University of Cambridge nor the names of its
  23       contributors may be used to endorse or promote products derived from
  24       this software without specific prior written permission.
  25
  26 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  27 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  30 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  31 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  32 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  33 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  34 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  35 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  36 POSSIBILITY OF SUCH DAMAGE.
  37 -----------------------------------------------------------------------------
  38 */
  39
  40
  41 /* This module contains the external function pcre_version(), which returns a
  42 string that identifies the PCRE version that is in use. */
  43
  44
  45 #include "config.h"
  46
  47 #include "pcre_internal.h"
  48
  49
  50 /*************************************************
  51 *          Return version string                 *
  52 *************************************************/
  53
  54 /* These macros are the standard way of turning unquoted text into C strings.
  55 They allow macros like PCRE_MAJOR to be defined without quotes, which is
  56 convenient for user programs that want to test its value. */
  57
  58 #define STRING(a)  # a
  59 #define XSTRING(s) STRING(s)
  60
  61 /* A problem turned up with PCRE_PRERELEASE, which is defined empty for
  62 production releases. Originally, it was used naively in this code:
  63
  64   return XSTRING(PCRE_MAJOR)
  65          "." XSTRING(PCRE_MINOR)
  66              XSTRING(PCRE_PRERELEASE)
  67          " " XSTRING(PCRE_DATE);
  68
  69 However, when PCRE_PRERELEASE is empty, this leads to an attempted expansion of
  70 STRING(). The C standard states: "If (before argument substitution) any
  71 argument consists of no preprocessing tokens, the behavior is undefined." It
  72 turns out the gcc treats this case as a single empty string - which is what we
  73 really want - but Visual C grumbles about the lack of an argument for the
  74 macro. Unfortunately, both are within their rights. To cope with both ways of
  75 handling this, I had resort to some messy hackery that does a test at run time.
  76 I could find no way of detecting that a macro is defined as an empty string at
  77 pre-processor time. This hack uses a standard trick for avoiding calling
  78 the STRING macro with an empty argument when doing the test. */
  79
  80 #ifdef COMPILE_PCRE8
  81 PCRE_EXP_DEFN const char * PCRE_CALL_CONVENTION
  82 pcre_version(void)
  83 #else
  84 PCRE_EXP_DEFN const char * PCRE_CALL_CONVENTION
  85 pcre16_version(void)
  86 #endif
  87 {
  88 return (XSTRING(Z PCRE_PRERELEASE)[1] == 0)?
  89   XSTRING(PCRE_MAJOR.PCRE_MINOR PCRE_DATE) :
  90   XSTRING(PCRE_MAJOR.PCRE_MINOR) XSTRING(PCRE_PRERELEASE PCRE_DATE);
  91 }
  92
  93 /* End of pcre_version.c */