Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2001-2011 Joel de Guzman
Chris@16: 
Chris@16:     Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16:     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: =============================================================================*/
Chris@16: #if !defined(SPIRIT_ACTION_JANUARY_07_2007_1128AM)
Chris@16: #define SPIRIT_ACTION_JANUARY_07_2007_1128AM
Chris@16: 
Chris@16: #if defined(_MSC_VER)
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/spirit/home/qi/meta_compiler.hpp>
Chris@16: #include <boost/spirit/home/qi/parser.hpp>
Chris@16: #include <boost/spirit/home/qi/detail/attributes.hpp>
Chris@16: #include <boost/spirit/home/support/argument.hpp>
Chris@16: #include <boost/spirit/home/support/context.hpp>
Chris@16: #include <boost/spirit/home/support/unused.hpp>
Chris@16: #include <boost/spirit/home/support/info.hpp>
Chris@16: #include <boost/spirit/home/support/action_dispatch.hpp>
Chris@16: #include <boost/spirit/home/support/handles_container.hpp>
Chris@16: 
Chris@16: #include <boost/mpl/bool.hpp>
Chris@16: #include <boost/mpl/if.hpp>
Chris@16: #include <boost/type_traits/remove_const.hpp>
Chris@16: #include <boost/type_traits/is_same.hpp>
Chris@16: 
Chris@16: namespace boost { namespace spirit { namespace qi
Chris@16: {
Chris@16:     BOOST_PP_REPEAT(SPIRIT_ARGUMENTS_LIMIT, SPIRIT_USING_ARGUMENT, _)
Chris@16: 
Chris@16:     template <typename Subject, typename Action>
Chris@16:     struct action : unary_parser<action<Subject, Action> >
Chris@16:     {
Chris@16:         typedef Subject subject_type;
Chris@16:         typedef Action action_type;
Chris@16: 
Chris@16:         template <typename Context, typename Iterator>
Chris@16:         struct attribute
Chris@16:           : traits::attribute_of<Subject, Context, Iterator>
Chris@16:         {};
Chris@16: 
Chris@16:         action(Subject const& subject_, Action f_)
Chris@16:           : subject(subject_), f(f_) {}
Chris@16: 
Chris@16: #ifndef BOOST_SPIRIT_ACTIONS_ALLOW_ATTR_COMPAT
Chris@16:         template <typename Iterator, typename Context
Chris@16:           , typename Skipper, typename Attribute>
Chris@16:         bool parse(Iterator& first, Iterator const& last
Chris@16:           , Context& context, Skipper const& skipper
Chris@16:           , Attribute& attr_) const
Chris@16:         {
Chris@16:             typedef typename attribute<Context, Iterator>::type attr_type;
Chris@16:             typedef traits::make_attribute<attr_type, Attribute> make_attribute;
Chris@16: 
Chris@16:             // create an attribute if one is not supplied
Chris@16:             typedef traits::transform_attribute<
Chris@16:                 typename make_attribute::type, attr_type, domain> transform;
Chris@16: 
Chris@16:             typename make_attribute::type made_attr = make_attribute::call(attr_);
Chris@16:             typename transform::type attr = transform::pre(made_attr);
Chris@16: 
Chris@16:             Iterator save = first;
Chris@16:             if (subject.parse(first, last, context, skipper, attr))
Chris@16:             {
Chris@16:                 // call the function, passing the attribute, the context.
Chris@16:                 // The client can return false to fail parsing.
Chris@16:                 if (traits::action_dispatch<Subject>()(f, attr, context)) 
Chris@16:                 {
Chris@16:                     // Do up-stream transformation, this integrates the results
Chris@16:                     // back into the original attribute value, if appropriate.
Chris@16:                     traits::post_transform(attr_, attr);
Chris@16:                     return true;
Chris@16:                 }
Chris@16: 
Chris@16:                 // reset iterators if semantic action failed the match
Chris@16:                 // retrospectively
Chris@16:                 first = save;
Chris@16:             }
Chris@16:             return false;
Chris@16:         }
Chris@16: #else
Chris@16:         template <typename Iterator, typename Context
Chris@16:           , typename Skipper, typename Attribute>
Chris@16:         bool parse(Iterator& first, Iterator const& last
Chris@16:           , Context& context, Skipper const& skipper
Chris@16:           , Attribute& attr) const
Chris@16:         {
Chris@16:             Iterator save = first;
Chris@16:             if (subject.parse(first, last, context, skipper, attr)) // Use the attribute as-is
Chris@16:             {
Chris@16:                 // call the function, passing the attribute, the context.
Chris@16:                 // The client can return false to fail parsing.
Chris@16:                 if (traits::action_dispatch<Subject>()(f, attr, context))
Chris@16:                     return true;
Chris@16: 
Chris@16:                 // reset iterators if semantic action failed the match
Chris@16:                 // retrospectively
Chris@16:                 first = save;
Chris@16:             }
Chris@16:             return false;
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Iterator, typename Context
Chris@16:           , typename Skipper>
Chris@16:         bool parse(Iterator& first, Iterator const& last
Chris@16:           , Context& context, Skipper const& skipper
Chris@16:           , unused_type) const
Chris@16:         {
Chris@16:             typedef typename attribute<Context, Iterator>::type attr_type;
Chris@16:             typedef traits::make_attribute<attr_type, unused_type> make_attribute;
Chris@16: 
Chris@16:             // synthesize the attribute since one is not supplied
Chris@16:             typedef traits::transform_attribute<
Chris@16:                 typename make_attribute::type, attr_type, domain> transform;
Chris@16: 
Chris@16:             typename make_attribute::type made_attr = make_attribute::call(unused_type());
Chris@16:             typename transform::type attr = transform::pre(made_attr);
Chris@16: 
Chris@16:             Iterator save = first;
Chris@16:             if (subject.parse(first, last, context, skipper, attr))
Chris@16:             {
Chris@16:                 // call the function, passing the attribute, the context.
Chris@16:                 // The client can return false to fail parsing.
Chris@16:                 if (traits::action_dispatch<Subject>()(f, attr, context))
Chris@16:                     return true;
Chris@16: 
Chris@16:                 // reset iterators if semantic action failed the match
Chris@16:                 // retrospectively
Chris@16:                 first = save;
Chris@16:             }
Chris@16:             return false;
Chris@16:         }
Chris@16: #endif
Chris@16: 
Chris@16:         template <typename Context>
Chris@16:         info what(Context& context) const
Chris@16:         {
Chris@16:             // the action is transparent (does not add any info)
Chris@16:             return subject.what(context);
Chris@16:         }
Chris@16: 
Chris@16:         Subject subject;
Chris@16:         Action f;
Chris@16: 
Chris@16:     private:
Chris@16:         // silence MSVC warning C4512: assignment operator could not be generated
Chris@16:         action& operator= (action const&);
Chris@16:     };
Chris@16: }}}
Chris@16: 
Chris@16: namespace boost { namespace spirit
Chris@16: {
Chris@16:     // Qi action meta-compiler
Chris@16:     template <>
Chris@16:     struct make_component<qi::domain, tag::action>
Chris@16:     {
Chris@16:         template <typename Sig>
Chris@16:         struct result;
Chris@16: 
Chris@16:         template <typename This, typename Elements, typename Modifiers>
Chris@16:         struct result<This(Elements, Modifiers)>
Chris@16:         {
Chris@16:             typedef typename
Chris@16:                 remove_const<typename Elements::car_type>::type
Chris@16:             subject_type;
Chris@16: 
Chris@16:             typedef typename
Chris@16:                 remove_const<typename Elements::cdr_type::car_type>::type
Chris@16:             action_type;
Chris@16: 
Chris@16:             typedef qi::action<subject_type, action_type> type;
Chris@16:         };
Chris@16: 
Chris@16:         template <typename Elements>
Chris@16:         typename result<make_component(Elements, unused_type)>::type
Chris@16:         operator()(Elements const& elements, unused_type) const
Chris@16:         {
Chris@16:             typename result<make_component(Elements, unused_type)>::type
Chris@16:                 result(elements.car, elements.cdr.car);
Chris@16:             return result;
Chris@16:         }
Chris@16:     };
Chris@16: }}
Chris@16: 
Chris@16: namespace boost { namespace spirit { namespace traits
Chris@16: {
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Subject, typename Action>
Chris@16:     struct has_semantic_action<qi::action<Subject, Action> >
Chris@16:       : mpl::true_ {};
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Subject, typename Action, typename Attribute
Chris@16:         , typename Context, typename Iterator>
Chris@16:     struct handles_container<qi::action<Subject, Action>, Attribute
Chris@16:         , Context, Iterator>
Chris@16:       : unary_handles_container<Subject, Attribute, Context, Iterator> {};
Chris@16: }}}
Chris@16: 
Chris@16: #endif