boost/spirit/home/classic/dynamic/impl/select.ipp
/*=============================================================================
Copyright (c) 2003 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)
=============================================================================*/
#ifndef BOOST_SPIRIT_SELECT_IPP
#define BOOST_SPIRIT_SELECT_IPP
#include <boost/spirit/home/classic/core/parser.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
///////////////////////////////////////////////////////////////////////////////
namespace impl {
///////////////////////////////////////////////////////////////////////////////
template <typename ParserT>
struct as_embedded_parser : public as_parser<ParserT>
{
typedef typename as_parser<ParserT>::type::derived_t::embed_t type;
};
///////////////////////////////////////////////////////////////////////////////
// no implementation here to catch unknown BehaviourT template arguments
template <typename ResultT, typename BehaviourT>
struct select_match_gen;
// implementation for the select_default_no_fail behaviour
template <typename ResultT>
struct select_match_gen<ResultT, select_default_no_fail> {
template <typename ScannerT>
static ResultT
do_ (ScannerT const &scan)
{
return scan.create_match(0, -1, scan.first, scan.first);
}
};
// implementation for the select_default_fail behaviour
template <typename ResultT>
struct select_match_gen<ResultT, select_default_fail> {
template <typename ScannerT>
static ResultT
do_ (ScannerT const &scan)
{
return scan.no_match();
}
};
///////////////////////////////////////////////////////////////////////////////
template <int N, typename ResultT, typename TupleT, typename BehaviourT>
struct parse_tuple_element {
BOOST_STATIC_CONSTANT(int, index = (TupleT::length - N));
template <typename ScannerT>
static ResultT
do_(TupleT const &t, ScannerT const &scan)
{
typedef typename ::phoenix::tuple_element<index, TupleT>::type parser_t;
typedef typename ScannerT::iterator_t iterator_t;
typedef typename parser_result<parser_t, ScannerT>::type result_t;
iterator_t save(scan.first);
::phoenix::tuple_index<index> const idx;
result_t result(t[idx].parse(scan));
if (result) {
return scan.create_match(result.length(), TupleT::length - N,
save, scan.first);
}
scan.first = save; // reset the input stream
return parse_tuple_element<N-1, ResultT, TupleT, BehaviourT>::
do_(t, scan);
}
};
template <typename ResultT, typename TupleT, typename BehaviourT>
struct parse_tuple_element<1, ResultT, TupleT, BehaviourT> {
BOOST_STATIC_CONSTANT(int, index = (TupleT::length - 1));
template <typename ScannerT>
static ResultT
do_(TupleT const &t, ScannerT const &scan)
{
typedef typename ::phoenix::tuple_element<index, TupleT>::type parser_t;
typedef typename ScannerT::iterator_t iterator_t;
typedef typename parser_result<parser_t, ScannerT>::type result_t;
iterator_t save(scan.first);
::phoenix::tuple_index<index> const idx;
result_t result(t[idx].parse(scan));
if (result) {
return scan.create_match(result.length(), TupleT::length - 1,
save, scan.first);
}
scan.first = save; // reset the input stream
return select_match_gen<ResultT, BehaviourT>::do_(scan);
}
};
///////////////////////////////////////////////////////////////////////////////
} // namespace impl
BOOST_SPIRIT_CLASSIC_NAMESPACE_END
}} // namespace boost::spirit
#endif // BOOST_SPIRIT_SELECT_IPP
