| // Copyright (c) 2001-2010 Hartmut Kaiser |
| // |
| // Distributed under the Boost Software License, Version 1.0. (See accompanying |
| // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| |
| #if !defined(SPIRIT_QI_ATTR_CAST_SEP_26_2009_0735PM) |
| #define SPIRIT_QI_ATTR_CAST_SEP_26_2009_0735PM |
| |
| #if defined(_MSC_VER) |
| #pragma once |
| #endif |
| |
| #include <boost/spirit/home/qi/meta_compiler.hpp> |
| #include <boost/spirit/home/qi/parser.hpp> |
| #include <boost/spirit/home/qi/domain.hpp> |
| #include <boost/spirit/home/support/unused.hpp> |
| #include <boost/spirit/home/support/info.hpp> |
| #include <boost/spirit/home/support/common_terminals.hpp> |
| #include <boost/spirit/home/qi/detail/attributes.hpp> |
| #include <boost/spirit/home/support/auxiliary/attr_cast.hpp> |
| |
| namespace boost { namespace spirit |
| { |
| /////////////////////////////////////////////////////////////////////////// |
| // Enablers |
| /////////////////////////////////////////////////////////////////////////// |
| |
| // enables attr_cast<>() pseudo parser |
| template <typename Expr, typename Exposed, typename Transformed> |
| struct use_terminal<qi::domain |
| , tag::stateful_tag<Expr, tag::attr_cast, Exposed, Transformed> > |
| : mpl::true_ {}; |
| }} |
| |
| namespace boost { namespace spirit { namespace qi |
| { |
| using spirit::attr_cast; |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // attr_cast_parser consumes the attribute of subject generator without |
| // generating anything |
| /////////////////////////////////////////////////////////////////////////// |
| template <typename Exposed, typename Transformed, typename Subject> |
| struct attr_cast_parser |
| : unary_parser<attr_cast_parser<Exposed, Transformed, Subject> > |
| { |
| typedef typename result_of::compile<qi::domain, Subject>::type |
| subject_type; |
| |
| typedef typename mpl::eval_if< |
| traits::not_is_unused<Transformed> |
| , mpl::identity<Transformed> |
| , traits::attribute_of<subject_type> >::type |
| transformed_attribute_type; |
| |
| attr_cast_parser(Subject const& subject) |
| : subject(subject) |
| { |
| // If you got an error_invalid_expression error message here, |
| // then the expression (Subject) is not a valid spirit qi |
| // expression. |
| BOOST_SPIRIT_ASSERT_MATCH(qi::domain, Subject); |
| } |
| |
| // If Exposed is given, we use the given type, otherwise all we can do |
| // is to guess, so we expose our inner type as an attribute and |
| // deal with the passed attribute inside the parse function. |
| template <typename Context, typename Iterator> |
| struct attribute |
| : mpl::if_<traits::not_is_unused<Exposed>, Exposed |
| , transformed_attribute_type> |
| {}; |
| |
| template <typename Iterator, typename Context, typename Skipper |
| , typename Attribute> |
| bool parse(Iterator& first, Iterator const& last |
| , Context& context, Skipper const& skipper |
| , Attribute& attr) const |
| { |
| // Find the real exposed attribute. If exposed is given, we use it |
| // otherwise we assume the exposed attribute type to be the actual |
| // attribute type as passed by the user. |
| typedef typename mpl::if_< |
| traits::not_is_unused<Exposed>, Exposed, Attribute>::type |
| exposed_attribute_type; |
| |
| // do down-stream transformation, provides attribute for embedded |
| // parser |
| typedef traits::transform_attribute< |
| exposed_attribute_type, transformed_attribute_type, domain> |
| transform; |
| |
| typename transform::type attr_ = transform::pre(attr); |
| |
| if (!compile<qi::domain>(subject). |
| parse(first, last, context, skipper, attr_)) |
| { |
| transform::fail(attr); |
| return false; |
| } |
| |
| // do up-stream transformation, this mainly integrates the results |
| // back into the original attribute value, if appropriate |
| traits::post_transform(attr, attr_); |
| return true; |
| } |
| |
| template <typename Context> |
| info what(Context& context) const |
| { |
| return info("attr_cast" |
| , compile<qi::domain>(subject).what(context)); |
| } |
| |
| Subject subject; |
| |
| private: |
| // silence MSVC warning C4512: assignment operator could not be generated |
| attr_cast_parser& operator= (attr_cast_parser const&); |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Parser generator: make_xxx function (objects) |
| /////////////////////////////////////////////////////////////////////////// |
| template <typename Expr, typename Exposed, typename Transformed |
| , typename Modifiers> |
| struct make_primitive< |
| tag::stateful_tag<Expr, tag::attr_cast, Exposed, Transformed>, Modifiers> |
| { |
| typedef attr_cast_parser<Exposed, Transformed, Expr> result_type; |
| |
| template <typename Terminal> |
| result_type operator()(Terminal const& term, unused_type) const |
| { |
| typedef tag::stateful_tag< |
| Expr, tag::attr_cast, Exposed, Transformed> tag_type; |
| using spirit::detail::get_stateful_data; |
| return result_type(get_stateful_data<tag_type>::call(term)); |
| } |
| }; |
| |
| |
| }}} |
| |
| #endif |