/[pcre]/code/trunk/pcre_version.c
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revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC revision 199 by ph10, Tue Jul 31 14:39:09 2007 UTC
# Line 6  Line 6 
6  and semantics are as close as possible to those of the Perl 5 language.  and semantics are as close as possible to those of the Perl 5 language.
7    
8                         Written by Philip Hazel                         Written by Philip Hazel
9             Copyright (c) 1997-2005 University of Cambridge             Copyright (c) 1997-2007 University of Cambridge
10    
11  -----------------------------------------------------------------------------  -----------------------------------------------------------------------------
12  Redistribution and use in source and binary forms, with or without  Redistribution and use in source and binary forms, with or without
# Line 42  POSSIBILITY OF SUCH DAMAGE. Line 42  POSSIBILITY OF SUCH DAMAGE.
42  string that identifies the PCRE version that is in use. */  string that identifies the PCRE version that is in use. */
43    
44    
45    #ifdef HAVE_CONFIG_H
46    #include <config.h>
47    #endif
48    
49  #include "pcre_internal.h"  #include "pcre_internal.h"
50    
51    
# Line 49  string that identifies the PCRE version Line 53  string that identifies the PCRE version
53  *          Return version string                 *  *          Return version string                 *
54  *************************************************/  *************************************************/
55    
56    /* These macros are the standard way of turning unquoted text into C strings.
57    They allow macros like PCRE_MAJOR to be defined without quotes, which is
58    convenient for user programs that want to test its value. */
59    
60  #define STRING(a)  # a  #define STRING(a)  # a
61  #define XSTRING(s) STRING(s)  #define XSTRING(s) STRING(s)
62    
63  EXPORT const char *  /* A problem turned up with PCRE_PRERELEASE, which is defined empty for
64    production releases. Originally, it was used naively in this code:
65    
66      return XSTRING(PCRE_MAJOR)
67             "." XSTRING(PCRE_MINOR)
68                 XSTRING(PCRE_PRERELEASE)
69             " " XSTRING(PCRE_DATE);
70    
71    However, when PCRE_PRERELEASE is empty, this leads to an attempted expansion of
72    STRING(). The C standard states: "If (before argument substitution) any
73    argument consists of no preprocessing tokens, the behavior is undefined." It
74    turns out the gcc treats this case as a single empty string - which is what we
75    really want - but Visual C grumbles about the lack of an argument for the
76    macro. Unfortunately, both are within their rights. To cope with both ways of
77    handling this, I had resort to some messy hackery that does a test at run time.
78    I could find no way of detecting that a macro is defined as an empty string at
79    pre-processor time. This hack uses a standard trick for avoiding calling
80    the STRING macro with an empty argument when doing the test. */
81    
82    PCRE_EXP_DEFN const char *
83  pcre_version(void)  pcre_version(void)
84  {  {
85  return XSTRING(PCRE_MAJOR) "." XSTRING(PCRE_MINOR) " " XSTRING(PCRE_DATE);  return (XSTRING(Z PCRE_PRERELEASE)[1] == 0)?
86      XSTRING(PCRE_MAJOR.PCRE_MINOR PCRE_DATE) :
87      XSTRING(PCRE_MAJOR.PCRE_MINOR) XSTRING(PCRE_PRERELEASE PCRE_DATE);
88  }  }
89    
90  /* End of pcre_version.c */  /* End of pcre_version.c */
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