143 lines
4.5 KiB
Plaintext
143 lines
4.5 KiB
Plaintext
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/*=============================================================================
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Copyright (c) 2002-2003 Joel de Guzman
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Copyright (c) 2002-2003 Hartmut Kaiser
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http://spirit.sourceforge.net/
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Use, modification and distribution is subject to the Boost Software
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License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#if !defined(BOOST_SPIRIT_SUBRULE_IPP)
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#define BOOST_SPIRIT_SUBRULE_IPP
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#include <boost/mpl/if.hpp>
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namespace boost { namespace spirit {
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BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
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template <typename FirstT, typename RestT>
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struct subrule_list;
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template <int ID, typename DefT, typename ContextT>
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struct subrule_parser;
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namespace impl {
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template <int N, typename ListT>
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struct get_subrule
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{
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// First case. ListT is non-empty but the list's
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// first item does not have the ID we are looking for.
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typedef typename get_subrule<N, typename ListT::rest_t>::type type;
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};
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template <int ID, typename DefT, typename ContextT, typename RestT>
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struct get_subrule<
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ID,
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subrule_list<
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subrule_parser<ID, DefT, ContextT>,
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RestT> >
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{
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// Second case. ListT is non-empty and the list's
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// first item has the ID we are looking for.
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typedef DefT type;
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};
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template <int ID>
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struct get_subrule<ID, nil_t>
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{
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// Third case. ListT is empty
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typedef nil_t type;
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};
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template <typename T1, typename T2>
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struct get_result_t {
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// If the result type dictated by the context is nil_t (no closures
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// present), then the whole subrule_parser return type is equal to
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// the return type of the right hand side of this subrule_parser,
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// otherwise it is equal to the dictated return value.
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typedef typename mpl::if_<
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boost::is_same<T1, nil_t>, T2, T1
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>::type type;
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};
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template <int ID, typename ScannerT, typename ContextResultT>
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struct get_subrule_result
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{
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typedef typename
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impl::get_subrule<ID, typename ScannerT::list_t>::type
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parser_t;
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typedef typename parser_result<parser_t, ScannerT>::type
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def_result_t;
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typedef typename match_result<ScannerT, ContextResultT>::type
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context_result_t;
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typedef typename get_result_t<context_result_t, def_result_t>::type
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type;
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};
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template <typename DefT, typename ScannerT, typename ContextResultT>
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struct get_subrule_parser_result
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{
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typedef typename parser_result<DefT, ScannerT>::type
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def_result_t;
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typedef typename match_result<ScannerT, ContextResultT>::type
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context_result_t;
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typedef typename get_result_t<context_result_t, def_result_t>::type
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type;
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};
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template <typename SubruleT, int ID>
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struct same_subrule_id
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{
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BOOST_STATIC_CONSTANT(bool, value = (SubruleT::id == ID));
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};
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template <typename RT, typename ScannerT, int ID>
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struct parse_subrule
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{
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template <typename ListT>
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static void
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do_parse(RT& r, ScannerT const& scan, ListT const& list, mpl::true_)
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{
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r = list.first.rhs.parse(scan);
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}
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template <typename ListT>
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static void
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do_parse(RT& r, ScannerT const& scan, ListT const& list, mpl::false_)
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{
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typedef typename ListT::rest_t::first_t subrule_t;
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mpl::bool_<same_subrule_id<subrule_t, ID>::value> same_id;
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do_parse(r, scan, list.rest, same_id);
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}
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static void
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do_(RT& r, ScannerT const& scan)
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{
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typedef typename ScannerT::list_t::first_t subrule_t;
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mpl::bool_<same_subrule_id<subrule_t, ID>::value> same_id;
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do_parse(r, scan, scan.list, same_id);
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}
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};
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}
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BOOST_SPIRIT_CLASSIC_NAMESPACE_END
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}} // namespace boost::spirit::impl
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#endif
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