qi/auxiliary/attr.hpp

0001 /*=============================================================================
0002     Copyright (c) 2001-2011 Hartmut Kaiser
0003     Copyright (c) 2001-2011 Joel de Guzman
0004
0005     Distributed under the Boost Software License, Version 1.0. (See accompanying
0006     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007 ==============================================================================*/
0008 #if !defined(BOOST_SPIRIT_ATTR_JUL_23_2008_0956AM)
0009 #define BOOST_SPIRIT_ATTR_JUL_23_2008_0956AM
0010
0011 #if defined(_MSC_VER)
0012 #pragma once
0013 #endif
0014
0015 #include <boost/mpl/bool.hpp>
0016 #include <boost/spirit/home/qi/domain.hpp>
0017 #include <boost/spirit/home/qi/parser.hpp>
0018 #include <boost/spirit/home/qi/detail/assign_to.hpp>
0019 #include <boost/spirit/home/qi/meta_compiler.hpp>
0020 #include <boost/spirit/home/support/common_terminals.hpp>
0021 #include <boost/spirit/home/support/handles_container.hpp>
0022 #include <boost/type_traits/add_reference.hpp>
0023 #include <boost/type_traits/add_const.hpp>
0024 #include <boost/type_traits/remove_const.hpp>
0025
0026 namespace boost { namespace spirit
0027 {
0028     ///////////////////////////////////////////////////////////////////////////
0029     // Enablers
0030     ///////////////////////////////////////////////////////////////////////////
0031     template <typename A0>       // enables attr()
0032     struct use_terminal<
0033             qi::domain, terminal_ex<tag::attr, fusion::vector1<A0> > >
0034       : mpl::true_ {};
0035
0036     template <>                  // enables *lazy* attr()
0037     struct use_lazy_terminal<qi::domain, tag::attr, 1>
0038       : mpl::true_ {};
0039
0040 }}
0041
0042 namespace boost { namespace spirit { namespace qi
0043 {
0044 #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
0045     using spirit::attr;
0046 #endif
0047     using spirit::attr_type;
0048
0049     template <typename Value>
0050     struct attr_parser : primitive_parser<attr_parser<Value> >
0051     {
0052         template <typename Context, typename Iterator>
0053         struct attribute : remove_const<Value> {};
0054
0055         attr_parser(typename add_reference<Value>::type value)
0056           : value_(value) {}
0057
0058         template <typename Iterator, typename Context
0059           , typename Skipper, typename Attribute>
0060         bool parse(Iterator& /*first*/, Iterator const& /*last*/
0061           , Context& /*context*/, Skipper const& /*skipper*/
0062           , Attribute& attr_) const
0063         {
0064             spirit::traits::assign_to(value_, attr_);
0065             return true;        // never consume any input, succeed always
0066         }
0067
0068         template <typename Context>
0069         info what(Context& /*context*/) const
0070         {
0071             return info("attr");
0072         }
0073
0074         Value value_;
0075     };
0076
0077     ///////////////////////////////////////////////////////////////////////////
0078     // Parser generators: make_xxx function (objects)
0079     ///////////////////////////////////////////////////////////////////////////
0080     template <typename Modifiers, typename A0>
0081     struct make_primitive<
0082         terminal_ex<tag::attr, fusion::vector1<A0> >
0083       , Modifiers>
0084     {
0085         typedef typename add_const<A0>::type const_value;
0086         typedef attr_parser<const_value> result_type;
0087
0088         template <typename Terminal>
0089         result_type operator()(Terminal const& term, unused_type) const
0090         {
0091             return result_type(fusion::at_c<0>(term.args));
0092         }
0093     };
0094 }}}
0095
0096 namespace boost { namespace spirit { namespace traits
0097 {
0098     ///////////////////////////////////////////////////////////////////////////
0099     template <typename T, typename Attr, typename Context, typename Iterator>
0100     struct handles_container<qi::attr_parser<T>, Attr, Context, Iterator>
0101       : traits::is_container<Attr> {};
0102 }}}
0103
0104 #endif
0105
0106