Perl Compatible Regular Expressions for Xbase++

The PCRE library is a set of functions that implement regular expression pattern matching using the same syntax and semantics as Perl 5. This DLL makes the powerful regular expression technology available for Xbase++. There is a sophisticated object oriented API as well as an easy to use functional interface available. This API-Implementation is further called pcre2.

Object oriented API

cRegexp()

Class for pcre2.

class methods

:new( <sPattern> ) Creates an instance of the cRegexp class. If the parameter <sPattern> is given the pattern is compiled immediately. This has the same effect as: oRe := cRegexp():new() followed by oRe:compile( <sPattern> ).

:compile( <sPattern> ) compiles the <sPattern> for further matching. An empty string is returned on success, an errormessage on failure. By calling :match() with different subjects they can be matched without compiling the pattern for every match, which boosts performance for repeating matches with the same pattern.

:clear() The method :clear() is part of the life cycle of the cRegexp-object and releases the system resources requested using the method :compile(). The object remains in existence and can later be reused with :compile() again. The :clear() should be called before a block which contains a compiled cRegexp-object is left to avoid memory leakage.

:match( <sSubject> ) Matches the given <sSubject> with the compiled pattern and returns an array of strings on matching success and an empty array on mismatch. The first array element is the complete maching part of <sSubject>. If there are bracket-catching subelements in the pattern, these substrings go into the following arrayelements accordingly.

:select( <aSubject> ) Matches all elements of the array <aSubject> with the compiled pattern and returns an array consisting only of the matching elements from <aSubject>.

:error() Returns the last error from compile() or new() and an empty string on success.

:version() Returns the used PCRE2 version as a string.

Functional API

regexpmatch( <sPattern>, <sSubject> ) Matches <sSubject> against <sPattern> and returns the same array as described in :match(). The whole livecycle of the cRegexp-object (new, compile, match, clear) is handled by the function - this is easy to use.

Example

  #pragma library( "pcre2.lib" )

  oHello := cRegexp():new( "hello (\w*)" )
  aSubs := oHello:match( "say hello Foo you fool" )
  sGreeted := aSubs[2] // <- "Foo"

  aSubs := regexpmatch( "hello (\w*)", "say hello Foo you fool" )
  sGreeted := aSubs[2] // <- "Foo"

Deployment

Files

pcre2.dll The DLL with the pcre2-routines from https://pcre.org/. This file must be installed in <Alaska 2.0 base directory>\xpp20\lib, <Alaska 2.0 base directory> usually is "C:\Program Files\Alaska Software". This file also must be delivered along with the applications runtime dlls as described in Xbase++ docs "Deployment of Xbase++ applications": "For simplicity, an Xbase++ application should be deployed with all the runtime files contained in the xpp<xx>\runtime folder". This file contains the BSD-licensed code from pcre.org and can be freely distributed.

pcre2.lib The import library is needed by the Xbase++-linker ALINK.EXE and should be also installed in <Alaska 2.0 base directory>\xpp20\lib. This file is only needed at link-time of the application.

pcre2.obj This is the C-API-interface from Xbase to pcre2 and is needed by the Xbase++-linker to build the application. It must be copied into the project-directory and added to the projects target with "Add existing file ...".This file is only needed at link-time of the application.

Copyright

The interface pcre2.obj is Copyright Axel Reinhold
The library pcre2.dll contains PCRE2 from http://pcre.org/ with BSD license.

Demo version

The Demoversion <arxpcre2d.10.x.y.z-x86.zip> returns only 400 matches. After that "no match" is always returned. Ask for a unlimited licensed version of pcre2 by mail to axel@toarx.de

Disclaimer

This interface library is supplied without any warranties of any kind, and you use it entirely at your own risk.