1 /*============================================================================= 2 Copyright (c) 2001-2011 Joel de Guzman 3 4 Distributed under the Boost Software License, Version 1.0. (See accompanying 5 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6 =============================================================================*/ 7 #if !defined(SPIRIT_ACTION_JANUARY_07_2007_1128AM) 8 #define SPIRIT_ACTION_JANUARY_07_2007_1128AM 9 10 #if defined(_MSC_VER) 11 #pragma once 12 #endif 13 14 #include <boost/spirit/home/qi/meta_compiler.hpp> 15 #include <boost/spirit/home/qi/parser.hpp> 16 #include <boost/spirit/home/qi/detail/attributes.hpp> 17 #include <boost/spirit/home/support/argument.hpp> 18 #include <boost/spirit/home/support/context.hpp> 19 #include <boost/spirit/home/support/unused.hpp> 20 #include <boost/spirit/home/support/info.hpp> 21 #include <boost/spirit/home/support/action_dispatch.hpp> 22 #include <boost/spirit/home/support/handles_container.hpp> 23 24 #include <boost/mpl/bool.hpp> 25 #include <boost/mpl/if.hpp> 26 #include <boost/type_traits/remove_const.hpp> 27 #include <boost/type_traits/is_same.hpp> 28 29 namespace boost { namespace spirit { namespace qi 30 { 31 BOOST_PP_REPEAT(SPIRIT_ARGUMENTS_LIMIT, SPIRIT_USING_ARGUMENT, _) 32 33 template <typename Subject, typename Action> 34 struct action : unary_parser<action<Subject, Action> > 35 { 36 typedef Subject subject_type; 37 typedef Action action_type; 38 39 template <typename Context, typename Iterator> 40 struct attribute 41 : traits::attribute_of<Subject, Context, Iterator> 42 {}; 43 actionboost::spirit::qi::action44 action(Subject const& subject_, Action f_) 45 : subject(subject_), f(f_) {} 46 47 #ifndef BOOST_SPIRIT_ACTIONS_ALLOW_ATTR_COMPAT 48 template <typename Iterator, typename Context 49 , typename Skipper, typename Attribute> parseboost::spirit::qi::action50 bool parse(Iterator& first, Iterator const& last 51 , Context& context, Skipper const& skipper 52 , Attribute& attr_) const 53 { 54 typedef typename attribute<Context, Iterator>::type attr_type; 55 typedef traits::make_attribute<attr_type, Attribute> make_attribute; 56 57 // create an attribute if one is not supplied 58 typedef traits::transform_attribute< 59 typename make_attribute::type, attr_type, domain> transform; 60 61 typename make_attribute::type made_attr = make_attribute::call(attr_); 62 typename transform::type attr = transform::pre(made_attr); 63 64 Iterator save = first; 65 if (subject.parse(first, last, context, skipper, attr)) 66 { 67 // call the function, passing the attribute, the context. 68 // The client can return false to fail parsing. 69 if (traits::action_dispatch<Subject>()(f, attr, context)) 70 { 71 // Do up-stream transformation, this integrates the results 72 // back into the original attribute value, if appropriate. 73 traits::post_transform(attr_, attr); 74 return true; 75 } 76 77 // reset iterators if semantic action failed the match 78 // retrospectively 79 first = save; 80 } 81 return false; 82 } 83 #else 84 template <typename Iterator, typename Context 85 , typename Skipper, typename Attribute> parseboost::spirit::qi::action86 bool parse(Iterator& first, Iterator const& last 87 , Context& context, Skipper const& skipper 88 , Attribute& attr) const 89 { 90 Iterator save = first; 91 if (subject.parse(first, last, context, skipper, attr)) // Use the attribute as-is 92 { 93 // call the function, passing the attribute, the context. 94 // The client can return false to fail parsing. 95 if (traits::action_dispatch<Subject>()(f, attr, context)) 96 return true; 97 98 // reset iterators if semantic action failed the match 99 // retrospectively 100 first = save; 101 } 102 return false; 103 } 104 105 template <typename Iterator, typename Context 106 , typename Skipper> parseboost::spirit::qi::action107 bool parse(Iterator& first, Iterator const& last 108 , Context& context, Skipper const& skipper 109 , unused_type) const 110 { 111 typedef typename attribute<Context, Iterator>::type attr_type; 112 typedef traits::make_attribute<attr_type, unused_type> make_attribute; 113 114 // synthesize the attribute since one is not supplied 115 typedef traits::transform_attribute< 116 typename make_attribute::type, attr_type, domain> transform; 117 118 typename make_attribute::type made_attr = make_attribute::call(unused_type()); 119 typename transform::type attr = transform::pre(made_attr); 120 121 Iterator save = first; 122 if (subject.parse(first, last, context, skipper, attr)) 123 { 124 // call the function, passing the attribute, the context. 125 // The client can return false to fail parsing. 126 if (traits::action_dispatch<Subject>()(f, attr, context)) 127 return true; 128 129 // reset iterators if semantic action failed the match 130 // retrospectively 131 first = save; 132 } 133 return false; 134 } 135 #endif 136 137 template <typename Context> whatboost::spirit::qi::action138 info what(Context& context) const 139 { 140 // the action is transparent (does not add any info) 141 return subject.what(context); 142 } 143 144 Subject subject; 145 Action f; 146 147 private: 148 // silence MSVC warning C4512: assignment operator could not be generated 149 action& operator= (action const&); 150 }; 151 }}} 152 153 namespace boost { namespace spirit 154 { 155 // Qi action meta-compiler 156 template <> 157 struct make_component<qi::domain, tag::action> 158 { 159 template <typename Sig> 160 struct result; 161 162 template <typename This, typename Elements, typename Modifiers> 163 struct result<This(Elements, Modifiers)> 164 { 165 typedef typename 166 remove_const<typename Elements::car_type>::type 167 subject_type; 168 169 typedef typename 170 remove_const<typename Elements::cdr_type::car_type>::type 171 action_type; 172 173 typedef qi::action<subject_type, action_type> type; 174 }; 175 176 template <typename Elements> 177 typename result<make_component(Elements, unused_type)>::type operator ()boost::spirit::make_component178 operator()(Elements const& elements, unused_type) const 179 { 180 typename result<make_component(Elements, unused_type)>::type 181 result(elements.car, elements.cdr.car); 182 return result; 183 } 184 }; 185 }} 186 187 namespace boost { namespace spirit { namespace traits 188 { 189 /////////////////////////////////////////////////////////////////////////// 190 template <typename Subject, typename Action> 191 struct has_semantic_action<qi::action<Subject, Action> > 192 : mpl::true_ {}; 193 194 /////////////////////////////////////////////////////////////////////////// 195 template <typename Subject, typename Action, typename Attribute 196 , typename Context, typename Iterator> 197 struct handles_container<qi::action<Subject, Action>, Attribute 198 , Context, Iterator> 199 : unary_handles_container<Subject, Attribute, Context, Iterator> {}; 200 }}} 201 202 #endif 203