| /*============================================================================= |
| 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<B>::type |
| > |
| type; |
| }; |
| |
| template <typename A, typename B> |
| static alternative< |
| typename as_parser<A>::type |
| , typename as_parser<B>::type |
| > |
| generate(A const& a, B const& b) |
| { |
| return alternative<BOOST_DEDUCED_TYPENAME as_parser<A>::type, |
| BOOST_DEDUCED_TYPENAME as_parser<B>::type> |
| (as_parser<A>::convert(a), as_parser<B>::convert(b)); |
| } |
| }; |
| |
| template <typename A, typename B> |
| alternative<A, B> |
| operator|(parser<A> const& a, parser<B> 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<B> 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<B> 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<B> 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<B> const& b); |
| |
| BOOST_SPIRIT_CLASSIC_NAMESPACE_END |
| |
| }} // namespace BOOST_SPIRIT_CLASSIC_NS |
| |
| #endif |
| |
| #include <boost/spirit/home/classic/core/composite/impl/alternative.ipp> |