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145 lines
5.3 KiB
145 lines
5.3 KiB
// Copyright (c) 2001-2011 Hartmut Kaiser |
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// |
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// Distributed under the Boost Software License, Version 1.0. (See accompanying |
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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#if !defined(SPIRIT_QI_ATTR_CAST_SEP_26_2009_0735PM) |
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#define SPIRIT_QI_ATTR_CAST_SEP_26_2009_0735PM |
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#if defined(_MSC_VER) |
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#pragma once |
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#endif |
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#include <boost/spirit/home/qi/meta_compiler.hpp> |
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#include <boost/spirit/home/qi/parser.hpp> |
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#include <boost/spirit/home/qi/domain.hpp> |
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#include <boost/spirit/home/support/unused.hpp> |
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#include <boost/spirit/home/support/info.hpp> |
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#include <boost/spirit/home/support/common_terminals.hpp> |
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#include <boost/spirit/home/qi/detail/attributes.hpp> |
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#include <boost/spirit/home/support/auxiliary/attr_cast.hpp> |
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namespace boost { namespace spirit |
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{ |
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/////////////////////////////////////////////////////////////////////////// |
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// Enablers |
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/////////////////////////////////////////////////////////////////////////// |
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// enables attr_cast<>() pseudo parser |
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template <typename Expr, typename Exposed, typename Transformed> |
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struct use_terminal<qi::domain |
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, tag::stateful_tag<Expr, tag::attr_cast, Exposed, Transformed> > |
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: mpl::true_ {}; |
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}} |
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namespace boost { namespace spirit { namespace qi |
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{ |
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using spirit::attr_cast; |
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/////////////////////////////////////////////////////////////////////////// |
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// attr_cast_parser consumes the attribute of subject generator without |
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// generating anything |
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/////////////////////////////////////////////////////////////////////////// |
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template <typename Exposed, typename Transformed, typename Subject> |
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struct attr_cast_parser |
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: unary_parser<attr_cast_parser<Exposed, Transformed, Subject> > |
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{ |
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typedef typename result_of::compile<qi::domain, Subject>::type |
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subject_type; |
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typedef typename mpl::eval_if< |
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traits::not_is_unused<Transformed> |
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, mpl::identity<Transformed> |
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, traits::attribute_of<subject_type> >::type |
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transformed_attribute_type; |
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attr_cast_parser(Subject const& subject) |
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: subject(subject) |
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{ |
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// If you got an error_invalid_expression error message here, |
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// then the expression (Subject) is not a valid spirit qi |
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// expression. |
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BOOST_SPIRIT_ASSERT_MATCH(qi::domain, Subject); |
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} |
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// If Exposed is given, we use the given type, otherwise all we can do |
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// is to guess, so we expose our inner type as an attribute and |
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// deal with the passed attribute inside the parse function. |
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template <typename Context, typename Iterator> |
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struct attribute |
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: mpl::if_<traits::not_is_unused<Exposed>, Exposed |
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, transformed_attribute_type> |
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{}; |
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template <typename Iterator, typename Context, typename Skipper |
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, typename Attribute> |
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bool parse(Iterator& first, Iterator const& last |
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, Context& context, Skipper const& skipper |
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, Attribute& attr) const |
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{ |
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// Find the real exposed attribute. If exposed is given, we use it |
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// otherwise we assume the exposed attribute type to be the actual |
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// attribute type as passed by the user. |
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typedef typename mpl::if_< |
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traits::not_is_unused<Exposed>, Exposed, Attribute>::type |
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exposed_attribute_type; |
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// do down-stream transformation, provides attribute for embedded |
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// parser |
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typedef traits::transform_attribute< |
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exposed_attribute_type, transformed_attribute_type, domain> |
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transform; |
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typename transform::type attr_ = transform::pre(attr); |
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if (!compile<qi::domain>(subject). |
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parse(first, last, context, skipper, attr_)) |
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{ |
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transform::fail(attr); |
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return false; |
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} |
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// do up-stream transformation, this mainly integrates the results |
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// back into the original attribute value, if appropriate |
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traits::post_transform(attr, attr_); |
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return true; |
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} |
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template <typename Context> |
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info what(Context& context) const |
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{ |
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return info("attr_cast" |
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, compile<qi::domain>(subject).what(context)); |
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} |
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Subject subject; |
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private: |
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// silence MSVC warning C4512: assignment operator could not be generated |
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attr_cast_parser& operator= (attr_cast_parser const&); |
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}; |
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/////////////////////////////////////////////////////////////////////////// |
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// Parser generator: make_xxx function (objects) |
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/////////////////////////////////////////////////////////////////////////// |
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template <typename Expr, typename Exposed, typename Transformed |
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, typename Modifiers> |
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struct make_primitive< |
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tag::stateful_tag<Expr, tag::attr_cast, Exposed, Transformed>, Modifiers> |
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{ |
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typedef attr_cast_parser<Exposed, Transformed, Expr> result_type; |
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template <typename Terminal> |
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result_type operator()(Terminal const& term, unused_type) const |
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{ |
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typedef tag::stateful_tag< |
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Expr, tag::attr_cast, Exposed, Transformed> tag_type; |
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using spirit::detail::get_stateful_data; |
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return result_type(get_stateful_data<tag_type>::call(term)); |
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} |
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}; |
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}}} |
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#endif
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