2000-09-26 11:48:28 +00:00
|
|
|
<!DOCTYPE HTML PUBLIC "-//w3c//dtd html 4.0 transitional//en">
|
|
|
|
|
|
|
|
|
|
<HTML>
|
|
|
|
|
|
|
|
|
|
<HEAD>
|
|
|
|
|
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
|
|
|
|
|
<META NAME="Template"
|
|
|
|
|
CONTENT="C:\PROGRAM FILES\MICROSOFT OFFICE\OFFICE\html.dot">
|
|
|
|
|
<META NAME="GENERATOR" CONTENT="Mozilla/4.5 [en] (Win98; I) [Netscape]">
|
|
|
|
|
<TITLE>Regex++ - FAQ</TITLE>
|
|
|
|
|
</HEAD>
|
|
|
|
|
|
|
|
|
|
<BODY BGCOLOR="#FFFFFF" LINK="#0000FF" VLINK="#800080">
|
|
|
|
|
<TABLE BORDER="0" CELLSPACING="0" CELLPADDING="7" WIDTH="100%">
|
|
|
|
|
<TR>
|
|
|
|
|
<TD VALIGN="TOP" WIDTH="50%"> <H3>
|
2000-09-26 19:02:50 +00:00
|
|
|
<IMG SRC="../../c++boost.gif" HEIGHT="86" WIDTH="276" ALT="C++ Boost"></H3>
|
2000-09-26 11:48:28 +00:00
|
|
|
</TD>
|
|
|
|
|
<TD VALIGN="TOP" WIDTH="50%"> <CENTER>
|
|
|
|
|
<H3> Regex++, FAQ.</H3>
|
|
|
|
|
</CENTER>
|
|
|
|
|
<CENTER>
|
|
|
|
|
<I>(version 3.01, 18 April 2000)</I>
|
|
|
|
|
</CENTER>
|
|
|
|
|
<PRE><I>Copyright (c) 1998-2000
|
|
|
|
|
Dr John Maddock
|
|
|
|
|
|
|
|
|
|
Permission to use, copy, modify, distribute and sell this software
|
|
|
|
|
and its documentation for any purpose is hereby granted without fee,
|
|
|
|
|
provided that the above copyright notice appear in all copies and
|
|
|
|
|
that both that copyright notice and this permission notice appear
|
|
|
|
|
in supporting documentation. Dr John Maddock makes no representations
|
|
|
|
|
about the suitability of this software for any purpose.
|
|
|
|
|
It is provided "as is" without express or implied warranty.</I></PRE>
|
|
|
|
|
|
|
|
|
|
</TD>
|
|
|
|
|
</TR>
|
|
|
|
|
</TABLE>
|
|
|
|
|
<P><FONT COLOR="#FF0000">Q. Configure says that my compiler is unable to merge
|
|
|
|
|
template instances, what does this mean?</FONT> </P>
|
|
|
|
|
<P>A. When you compile template code, you can end up with the same template
|
|
|
|
|
instances in multiple translation units - this will lead to link time errors
|
|
|
|
|
unless your compiler/linker is smart enough to merge these template instances
|
|
|
|
|
into a single record in the executable file. If you see this warning after
|
|
|
|
|
running configure, then you can still link to libregex++.a if: </P>
|
|
|
|
|
<OL>
|
|
|
|
|
<LI> You use only the low-level template classes (reg_expression<>
|
|
|
|
|
match_results<> etc), from a single translation unit, and use no other part
|
|
|
|
|
of regex++.</LI>
|
|
|
|
|
<LI> You use only the POSIX API functions (regcomp regexec etc), and no other
|
|
|
|
|
part of regex++.</LI>
|
|
|
|
|
<LI> You use only the high level class RegEx, and no other part of regex++.
|
|
|
|
|
</LI>
|
|
|
|
|
</OL>
|
|
|
|
|
Another option is to create a master include file, which #include's all the
|
|
|
|
|
regex++ source files, and all the source files in which you use regex++. You
|
|
|
|
|
then compile and link this master file as a single translation unit. <P><FONT
|
|
|
|
|
COLOR="#FF0000">Q. Configure says that my compiler is unable to merge template
|
|
|
|
|
instances from archive files, what does this mean?</FONT> </P>
|
|
|
|
|
<P>A. When you compile template code, you can end up with the same template
|
|
|
|
|
instances in multiple translation units - this will lead to link time errors
|
|
|
|
|
unless your compiler/linker is smart enough to merge these template instances
|
|
|
|
|
into a single record in the executable file. Some compilers are able to do this
|
|
|
|
|
for normal .cpp or .o files, but fail if the object file has been placed in a
|
|
|
|
|
library archive. If you see this warning after running configure, then you can
|
|
|
|
|
still link to libregex++.a if: </P>
|
|
|
|
|
<OL>
|
|
|
|
|
<LI> You use only the low-level template classes (reg_expression<>
|
|
|
|
|
match_results<> etc), and use no other part of regex++.</LI>
|
|
|
|
|
<LI> You use only the POSIX API functions (regcomp regexec etc), and no other
|
|
|
|
|
part of regex++.</LI>
|
|
|
|
|
<LI> You use only the high level class RegEx, and no other part of regex++.
|
|
|
|
|
</LI>
|
|
|
|
|
</OL>
|
|
|
|
|
Another option is to add the regex++ source files directly to your project
|
|
|
|
|
instead of linking to libregex++.a, generally you should do this only if you
|
|
|
|
|
are getting link time errors with libregex++.a. <P><FONT COLOR="#FF0000">Q.
|
|
|
|
|
Configure says that my compiler can't merge templates containing switch
|
|
|
|
|
statements, what does this mean?</FONT> </P>
|
|
|
|
|
<P>A. Some compilers can't merge templates that contain static data - this
|
|
|
|
|
includes switch statements which implicitly generate static data as well as
|
|
|
|
|
code. Principally this affects the egcs compiler - but note gcc 2.81 also
|
|
|
|
|
suffers from this problem - the compiler will compile and link the code - but
|
|
|
|
|
the code will not run because the code and the static data it uses have become
|
|
|
|
|
separated. The default behaviour of regex++ is to try and fix this problem by
|
|
|
|
|
declaring "problem" templates inside unnamed namespaces, so that the
|
|
|
|
|
templates have internal linkage. Note that this can result in a great deal of
|
|
|
|
|
code bloat. If the compiler doesn't support namespaces, or if code bloat
|
|
|
|
|
becomes a problem, then follow the guidelines above for placing all the
|
|
|
|
|
templates used in a single translation unit, and edit jm_opt.h so that
|
|
|
|
|
BOOST_RE_NO_TEMPLATE_SWITCH_MERGE is no longer defined. </P>
|
|
|
|
|
<P><FONT COLOR="#FF0000">Q. I can't get regex++ to work with escape characters,
|
|
|
|
|
what's going on?</FONT> </P>
|
|
|
|
|
<P>A. If you embed regular expressions in C++ code, then remember that escape
|
|
|
|
|
characters are processed twice: once by the C++ compiler, and once by the
|
|
|
|
|
regex++ expression compiler, so to pass the regular expression \d+ to regex++,
|
|
|
|
|
you need to embed "\\d+" in your code. Likewise to match a literal
|
|
|
|
|
backslash you will need to embed "\\\\" in your code. </P>
|
|
|
|
|
<P><FONT COLOR="#FF0000">Q. Why don't character ranges work properly?</FONT>
|
|
|
|
|
<BR>
|
|
|
|
|
A. The POSIX standard specifies that character range expressions are locale
|
|
|
|
|
sensitive - so for example the expression [A-Z] will match any collating
|
|
|
|
|
element that collates between 'A' and 'Z'. That means that for most locales
|
|
|
|
|
other than "C" or "POSIX", [A-Z] would match the single
|
|
|
|
|
character 't' for example, which is not what most people expect - or at least
|
|
|
|
|
not what most people have come to expect from regular expression engines. For
|
|
|
|
|
this reason, the default behaviour of regex++ is to turn locale sensitive
|
|
|
|
|
collation off by setting the regbase::nocollate compile time flag (this is set
|
|
|
|
|
by regbase::normal). However if you set a non-default compile time flag - for
|
|
|
|
|
example regbase::extended or regbase::basic, then locale dependent collation
|
|
|
|
|
will be enabled, this also applies to the POSIX API functions which use either
|
|
|
|
|
regbase::extended or regbase::basic internally, in the latter case use
|
|
|
|
|
REG_NOCOLLATE in combination with either REG_BASIC or REG_EXTENDED when
|
|
|
|
|
invoking regcomp if you don't want locale sensitive collation. <I>[Note - when
|
|
|
|
|
regbase::nocollate in effect, the library behaves "as if" the
|
|
|
|
|
LC_COLLATE locale category were always "C", regardless of what its
|
|
|
|
|
actually set to - end note</I>]. </P>
|
|
|
|
|
<P><FONT COLOR="#FF0000"> Q. Why can't I use the "convenience"
|
|
|
|
|
versions of query_match/reg_search/reg_grep/reg_format/reg_merge?</FONT> </P>
|
|
|
|
|
<P>A. These versions may or may not be available depending upon the
|
|
|
|
|
capabilities of your compiler, the rules determining the format of these
|
|
|
|
|
functions are quite complex - and only the versions visible to a standard
|
|
|
|
|
compliant compiler are given in the help. To find out what your compiler
|
|
|
|
|
supports, run <boost/regex.hpp> through your C++ pre-processor, and
|
|
|
|
|
search the output file for the function that you are interested in. </P>
|
|
|
|
|
<P><FONT COLOR="#FF0000">Q. Why are there no throw specifications on any of the
|
|
|
|
|
functions? What exceptions can the library throw?</FONT> </P>
|
|
|
|
|
<P>A. Not all compilers support (or honor) throw specifications, others support
|
|
|
|
|
them but with reduced efficiency. Throw specifications may be added at a later
|
|
|
|
|
date as compilers begin to handle this better. The library should throw only
|
|
|
|
|
three types of exception: boost::bad_expression can be thrown by reg_expression
|
|
|
|
|
when compiling a regular expression; boost::bad_pattern can be thrown by the
|
|
|
|
|
class sub_match's conversion operators; finally std::bad_alloc can be thrown by
|
|
|
|
|
just about any of the functions in this library. <BR>
|
|
|
|
|
</P>
|
|
|
|
|
<HR>
|
|
|
|
|
<P><I>Copyright <A HREF="mailto:John_Maddock@compuserve.com">Dr John
|
|
|
|
|
Maddock</A> 1998-2000 all rights reserved.</I> </P>
|
|
|
|
|
</BODY>
|
|
|
|
|
</HTML>
|
|
|
|
|
|
