boost/spirit/core/composite/sequential_or.hpp
/*=============================================================================
Copyright (c) 1998-2003 Joel de Guzman
Copyright (c) 2001 Daniel Nuffer
Copyright (c) 2002 Hartmut Kaiser
http://spirit.sourceforge.net/
Use, modification and distribution is subject to 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_SEQUENTIAL_OR_HPP)
#define BOOST_SPIRIT_SEQUENTIAL_OR_HPP
#include <boost/spirit/core/parser.hpp>
#include <boost/spirit/core/primitives/primitives.hpp>
#include <boost/spirit/core/composite/composite.hpp>
#include <boost/spirit/meta/as_parser.hpp>
namespace boost { namespace spirit {
///////////////////////////////////////////////////////////////////////////
//
// sequential-or class
//
// Handles expressions of the form:
//
// a || b
//
// Equivalent to
//
// a | b | a >> b;
//
// where a and b are parsers. The expression returns a composite
// parser that matches matches a or b in sequence. One (not both) of
// the operands may be a literal char, wchar_t or a primitive string
// char const*, wchar_t const*.
//
///////////////////////////////////////////////////////////////////////////
struct sequential_or_parser_gen;
template <typename A, typename B>
struct sequential_or : public binary<A, B, parser<sequential_or<A, B> > >
{
typedef sequential_or<A, B> self_t;
typedef binary_parser_category parser_category_t;
typedef sequential_or_parser_gen parser_generator_t;
typedef binary<A, B, parser<self_t> > base_t;
sequential_or(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 ma = this->left().parse(scan))
{
save = scan.first;
if (result_t mb = this->right().parse(scan))
{
// matched a b
scan.concat_match(ma, mb);
return ma;
}
else
{
// matched a
scan.first = save;
return ma;
}
}
scan.first = save;
}
// matched b
return this->right().parse(scan);
}
};
struct sequential_or_parser_gen
{
template <typename A, typename B>
struct result
{
typedef
sequential_or<
typename as_parser<A>::type
, typename as_parser<B>::type
>
type;
};
template <typename A, typename B>
static sequential_or<
typename as_parser<A>::type
, typename as_parser<B>::type
>
generate(A const& a, B const& b)
{
return sequential_or<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>
sequential_or<A, B>
operator||(parser<A> const& a, parser<B> const& b);
template <typename A>
sequential_or<A, chlit<char> >
operator||(parser<A> const& a, char b);
template <typename B>
sequential_or<chlit<char>, B>
operator||(char a, parser<B> const& b);
template <typename A>
sequential_or<A, strlit<char const*> >
operator||(parser<A> const& a, char const* b);
template <typename B>
sequential_or<strlit<char const*>, B>
operator||(char const* a, parser<B> const& b);
template <typename A>
sequential_or<A, chlit<wchar_t> >
operator||(parser<A> const& a, wchar_t b);
template <typename B>
sequential_or<chlit<wchar_t>, B>
operator||(wchar_t a, parser<B> const& b);
template <typename A>
sequential_or<A, strlit<wchar_t const*> >
operator||(parser<A> const& a, wchar_t const* b);
template <typename B>
sequential_or<strlit<wchar_t const*>, B>
operator||(wchar_t const* a, parser<B> const& b);
}} // namespace boost::spirit
#endif
#include <boost/spirit/core/composite/impl/sequential_or.ipp>
