EVOLUTION-MANAGER

Edit File: alternative.hpp

/*=============================================================================
    Copyright (c) 1998-2003 Joel de Guzman
    Copyright (c) 2001 Daniel Nuffer
    Copyright (c) 2002 Hartmut Kaiser
    http://spirit.sourceforge.net/

Distributed under the Boost Software License, Version 1.0. (See accompanying
  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#if !defined(BOOST_SPIRIT_ALTERNATIVE_HPP)
#define BOOST_SPIRIT_ALTERNATIVE_HPP

#include <boost/spirit/home/classic/namespace.hpp>
#include <boost/spirit/home/classic/core/parser.hpp>
#include <boost/spirit/home/classic/core/primitives/primitives.hpp>
#include <boost/spirit/home/classic/core/composite/composite.hpp>
#include <boost/spirit/home/classic/meta/as_parser.hpp>

namespace boost { namespace spirit {

BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN

///////////////////////////////////////////////////////////////////////////
    //
    //  alternative class
    //
    //      Handles expressions of the form:
    //
    //          a | b
    //
    //      where a and b are parsers. The expression returns a composite
    //      parser that matches a or b. One (not both) of the operands may
    //      be a literal char, wchar_t or a primitive string char const*,
    //      wchar_t const*.
    //
    //      The expression is short circuit evaluated. b is never touched
    //      when a is returns a successful match.
    //
    ///////////////////////////////////////////////////////////////////////////
    struct alternative_parser_gen;
    
#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
#pragma warning(push)
#pragma warning(disable:4512) //assignment operator could not be generated
#endif

template <typename A, typename B>
 struct alternative
 : public binary<A, B, parser<alternative<A, B> > >
 {
 typedef alternative<A, B> self_t;
 typedef binary_parser_category parser_category_t;
 typedef alternative_parser_gen parser_generator_t;
 typedef binary<A, B, parser<self_t> > base_t;
 
 alternative(A const& a, B const& b)
 : base_t(a, b) {}
 
 template <typename ScannerT>
 typename parser_result<self_t, ScannerT>::type
 parse(ScannerT const& scan) const
 {
 typedef typename parser_result<self_t, ScannerT>::type result_t;
 typedef typename ScannerT::iterator_t iterator_t;
 { // scope for save
 iterator_t save = scan.first;
 if (result_t hit = this->left().parse(scan))
 return hit;
 scan.first = save;
 }
 return this->right().parse(scan);
 }
 };

#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
#pragma warning(pop)
#endif
 
 struct alternative_parser_gen
 {
 template <typename A, typename B>
 struct result 
 {
 typedef 
 alternative<
 typename as_parser<A>::type
 , typename as_parser::type
 > 
 type;
 };
 
 template <typename A, typename B>
 static alternative<
 typename as_parser<A>::type
 , typename as_parser::type
 >
 generate(A const& a, B const& b)
 {
 return alternative<BOOST_DEDUCED_TYPENAME as_parser<A>::type,
 BOOST_DEDUCED_TYPENAME as_parser::type>
 (as_parser<A>::convert(a), as_parser::convert(b));
 }
 };
 
 template <typename A, typename B>
 alternative<A, B>
 operator|(parser<A> const& a, parser const& b);
 
 template <typename A>
 alternative<A, chlit<char> >
 operator|(parser<A> const& a, char b);
 
 template <typename B>
 alternative<chlit<char>, B>
 operator|(char a, parser const& b);
 
 template <typename A>
 alternative<A, strlit<char const*> >
 operator|(parser<A> const& a, char const* b);
 
 template <typename B>
 alternative<strlit<char const*>, B>
 operator|(char const* a, parser const& b);
 
 template <typename A>
 alternative<A, chlit<wchar_t> >
 operator|(parser<A> const& a, wchar_t b);
 
 template <typename B>
 alternative<chlit<wchar_t>, B>
 operator|(wchar_t a, parser const& b);
 
 template <typename A>
 alternative<A, strlit<wchar_t const*> >
 operator|(parser<A> const& a, wchar_t const* b);
 
 template <typename B>
 alternative<strlit<wchar_t const*>, B>
 operator|(wchar_t const* a, parser const& b);

BOOST_SPIRIT_CLASSIC_NAMESPACE_END

}} // namespace BOOST_SPIRIT_CLASSIC_NS

#endif

#include <boost/spirit/home/classic/core/composite/impl/alternative.ipp>