-/* $Cambridge: exim/src/src/pcre/pcre_version.c,v 1.1 2005/06/15 08:57:10 ph10 Exp $ */
+/* $Cambridge: exim/src/src/pcre/pcre_version.c,v 1.4 2007/01/23 15:08:45 ph10 Exp $ */
/*************************************************
* Perl-Compatible Regular Expressions *
and semantics are as close as possible to those of the Perl 5 language.
Written by Philip Hazel
- Copyright (c) 1997-2005 University of Cambridge
+ Copyright (c) 1997-2006 University of Cambridge
-----------------------------------------------------------------------------
Redistribution and use in source and binary forms, with or without
* Return version string *
*************************************************/
+/* These macros are the standard way of turning unquoted text into C strings.
+They allow macros like PCRE_MAJOR to be defined without quotes, which is
+convenient for user programs that want to test its value. */
+
#define STRING(a) # a
#define XSTRING(s) STRING(s)
-EXPORT const char *
+/* A problem turned up with PCRE_PRERELEASE, which is defined empty for
+production releases. Originally, it was used naively in this code:
+
+ return XSTRING(PCRE_MAJOR)
+ "." XSTRING(PCRE_MINOR)
+ XSTRING(PCRE_PRERELEASE)
+ " " XSTRING(PCRE_DATE);
+
+However, when PCRE_PRERELEASE is empty, this leads to an attempted expansion of
+STRING(). The C standard states: "If (before argument substitution) any
+argument consists of no preprocessing tokens, the behavior is undefined." It
+turns out the gcc treats this case as a single empty string - which is what we
+really want - but Visual C grumbles about the lack of an argument for the
+macro. Unfortunately, both are within their rights. To cope with both ways of
+handling this, I had resort to some messy hackery that does a test at run time.
+I could find no way of detecting that a macro is defined as an empty string at
+pre-processor time. This hack uses a standard trick for avoiding calling
+the STRING macro with an empty argument when doing the test. */
+
+PCRE_DATA_SCOPE const char *
pcre_version(void)
{
-return XSTRING(PCRE_MAJOR) "." XSTRING(PCRE_MINOR) " " XSTRING(PCRE_DATE);
+return (XSTRING(Z PCRE_PRERELEASE)[1] == 0)?
+ XSTRING(PCRE_MAJOR.PCRE_MINOR PCRE_DATE) :
+ XSTRING(PCRE_MAJOR.PCRE_MINOR) XSTRING(PCRE_PRERELEASE PCRE_DATE);
}
/* End of pcre_version.c */