regexmatcher.hpp

Go to the documentation of this file.

//==================================================================================================
/// \file
/// This header file is part of module \alib_strings of the \aliblong.
///
/// \emoji :copyright: 2013-2024 A-Worx GmbH, Germany.
/// Published under \ref mainpage_license "Boost Software License".
//==================================================================================================
#ifndef HPP_ALIB_STRINGS_UTIL_REGEXMATCHER
#define HPP_ALIB_STRINGS_UTIL_REGEXMATCHER 1
#pragma once
#include "alib/strings/cstring.hpp"
 
#if ALIB_FEAT_BOOST_REGEX && (!ALIB_CHARACTERS_WIDE || ALIB_CHARACTERS_NATIVE_WCHAR)
 
namespace alib {  namespace strings { namespace util  {
 
//==================================================================================================
/// This utility class wraps \https{boost::regex library,www.boost.org} and interfaces
/// \alib_strings with it.
///
/// The availability of the class is dependent on compiler symbol \ref ALIB_FEAT_BOOST_REGEX
/// which has to be \c true, and in parallel either \ref ALIB_CHARACTERS_WIDE is \c false or
/// \ref ALIB_CHARACTERS_NATIVE_WCHAR equals \c true.
///
/// Method #Compile accepts the pattern string and compiles it to \b boost::regex.
/// Subsequent invocations of #Match will then use the compiled regular expression for testing
/// a given string.
///
/// The syntax of the regular expressions is compatible to
/// \https{Perl Regular Expressions,perldoc.perl.org/perlretut.html}.
///
/// \note
///   This is a very basic wrapper that supports just the <b>bare minimum of the features</b>
///   available in the original \b boost::regex library.
///   I.e, the expression syntax is fixed to be \e Perl-compatible and no string replacement
///   features or even match positioning are available.
//==================================================================================================
class RegexMatcher
{
    protected:
        /// This is the internal regex matcher. Yes, a nasty \c reinterpret_cast is performed in the
        /// compilation unit. This is for avoiding the inclusion of external headers with \alib
        /// headers at the expense of an otherwise unnecessary heap allocation.
        void*           boostRegex                                                        = nullptr;
 
    public:
        //==========================================================================================
        /// Constructs a RegexMatcher to work on a given string. Passes the optional parameters
        /// to method #Compile.
        ///
        /// @param  pattern      The string pattern to match.
        ///                      Defaults to \b NULL_STRING to allow parameterless construction,
        ///                      with later invocation of #Compile.
        //==========================================================================================
        RegexMatcher( const String& pattern= NULL_STRING  )
        {
            Compile( pattern );
        }
 
        //==========================================================================================
        /// Destructor.
        //==========================================================================================
        ALIB_API
        ~RegexMatcher();
 
    public:
        //==========================================================================================
        /// Resets this object to use the given pattern.
        ///
        /// @param  pattern      The string pattern to match.
        //==========================================================================================
        ALIB_API
        void Compile( const String& pattern );
 
        //==========================================================================================
        /// Tests if given \p{haystack} matches the actual pattern.
        /// If #Compile was not invoked or an empty pattern string was given, \c true is returned.
        ///
        /// @param haystack  The string to test.
        /// @return \c true if given \p{haystack} matches the actual pattern, \c false otherwise.
        //==========================================================================================
        ALIB_API
        bool   Match( const String& haystack );
 
}; // class RegexMatcher
 
}} // namespace alib[::strings::util]
 
/// Type alias in namespace \b alib.
using     RegexMatcher=     strings::util::RegexMatcher;
 
} // namespace [alib]
 
#endif // ALIB_FEAT_BOOST_REGEX && (!ALIB_CHARACTERS_WIDE || ALIB_CHARACTERS_NATIVE_WCHAR)
#endif // HPP_ALIB_STRINGS_UTIL_REGEXMATCHER