1 // Copyright (c) 2001-2011 Hartmut Kaiser 2 // 3 // Distributed under the Boost Software License, Version 1.0. (See accompanying 4 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 5 6 #if !defined(SPIRIT_QI_ATTR_CAST_SEP_26_2009_0735PM) 7 #define SPIRIT_QI_ATTR_CAST_SEP_26_2009_0735PM 8 9 #if defined(_MSC_VER) 10 #pragma once 11 #endif 12 13 #include <boost/spirit/home/qi/meta_compiler.hpp> 14 #include <boost/spirit/home/qi/parser.hpp> 15 #include <boost/spirit/home/qi/domain.hpp> 16 #include <boost/spirit/home/support/unused.hpp> 17 #include <boost/spirit/home/support/info.hpp> 18 #include <boost/spirit/home/support/common_terminals.hpp> 19 #include <boost/spirit/home/qi/detail/attributes.hpp> 20 #include <boost/spirit/home/support/auxiliary/attr_cast.hpp> 21 22 namespace boost { namespace spirit 23 { 24 /////////////////////////////////////////////////////////////////////////// 25 // Enablers 26 /////////////////////////////////////////////////////////////////////////// 27 28 // enables attr_cast<>() pseudo parser 29 template <typename Expr, typename Exposed, typename Transformed> 30 struct use_terminal<qi::domain 31 , tag::stateful_tag<Expr, tag::attr_cast, Exposed, Transformed> > 32 : mpl::true_ {}; 33 }} 34 35 namespace boost { namespace spirit { namespace qi 36 { 37 using spirit::attr_cast; 38 39 /////////////////////////////////////////////////////////////////////////// 40 // attr_cast_parser consumes the attribute of subject generator without 41 // generating anything 42 /////////////////////////////////////////////////////////////////////////// 43 template <typename Exposed, typename Transformed, typename Subject> 44 struct attr_cast_parser 45 : unary_parser<attr_cast_parser<Exposed, Transformed, Subject> > 46 { 47 typedef typename result_of::compile<qi::domain, Subject>::type 48 subject_type; 49 50 typedef typename mpl::eval_if< 51 traits::not_is_unused<Transformed> 52 , mpl::identity<Transformed> 53 , traits::attribute_of<subject_type> >::type 54 transformed_attribute_type; 55 attr_cast_parserboost::spirit::qi::attr_cast_parser56 attr_cast_parser(Subject const& subject_) 57 : subject(subject_) 58 { 59 // If you got an error_invalid_expression error message here, 60 // then the expression (Subject) is not a valid spirit qi 61 // expression. 62 BOOST_SPIRIT_ASSERT_MATCH(qi::domain, Subject); 63 } 64 65 // If Exposed is given, we use the given type, otherwise all we can do 66 // is to guess, so we expose our inner type as an attribute and 67 // deal with the passed attribute inside the parse function. 68 template <typename Context, typename Iterator> 69 struct attribute 70 : mpl::if_<traits::not_is_unused<Exposed>, Exposed 71 , transformed_attribute_type> 72 {}; 73 74 template <typename Iterator, typename Context, typename Skipper 75 , typename Attribute> parseboost::spirit::qi::attr_cast_parser76 bool parse(Iterator& first, Iterator const& last 77 , Context& context, Skipper const& skipper 78 , Attribute& attr_param) const 79 { 80 // Find the real exposed attribute. If exposed is given, we use it 81 // otherwise we assume the exposed attribute type to be the actual 82 // attribute type as passed by the user. 83 typedef typename mpl::if_< 84 traits::not_is_unused<Exposed>, Exposed, Attribute>::type 85 exposed_attribute_type; 86 87 // do down-stream transformation, provides attribute for embedded 88 // parser 89 typedef traits::transform_attribute< 90 exposed_attribute_type, transformed_attribute_type, domain> 91 transform; 92 93 typename transform::type attr_ = transform::pre(attr_param); 94 95 if (!compile<qi::domain>(subject). 96 parse(first, last, context, skipper, attr_)) 97 { 98 transform::fail(attr_param); 99 return false; 100 } 101 102 // do up-stream transformation, this mainly integrates the results 103 // back into the original attribute value, if appropriate 104 traits::post_transform(attr_param, attr_); 105 return true; 106 } 107 108 template <typename Context> whatboost::spirit::qi::attr_cast_parser109 info what(Context& context) const 110 { 111 return info("attr_cast" 112 , compile<qi::domain>(subject).what(context)); 113 } 114 115 Subject subject; 116 117 private: 118 // silence MSVC warning C4512: assignment operator could not be generated 119 attr_cast_parser& operator= (attr_cast_parser const&); 120 }; 121 122 /////////////////////////////////////////////////////////////////////////// 123 // Parser generator: make_xxx function (objects) 124 /////////////////////////////////////////////////////////////////////////// 125 template <typename Expr, typename Exposed, typename Transformed 126 , typename Modifiers> 127 struct make_primitive< 128 tag::stateful_tag<Expr, tag::attr_cast, Exposed, Transformed>, Modifiers> 129 { 130 typedef attr_cast_parser<Exposed, Transformed, Expr> result_type; 131 132 template <typename Terminal> operator ()boost::spirit::qi::make_primitive133 result_type operator()(Terminal const& term, unused_type) const 134 { 135 typedef tag::stateful_tag< 136 Expr, tag::attr_cast, Exposed, Transformed> tag_type; 137 using spirit::detail::get_stateful_data; 138 return result_type(get_stateful_data<tag_type>::call(term)); 139 } 140 }; 141 142 143 }}} 144 145 #endif 146