87 lines
2.8 KiB
C++
Executable File
87 lines
2.8 KiB
C++
Executable File
/*=============================================================================
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Copyright (c) 2001-2007 Joel de Guzman
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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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=============================================================================*/
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#if !defined(SPIRIT_OPTIONAL_MARCH_23_2007_1117PM)
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#define SPIRIT_OPTIONAL_MARCH_23_2007_1117PM
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#include <boost/spirit/home/support/component.hpp>
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#include <boost/spirit/home/support/unused.hpp>
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#include <boost/spirit/home/support/attribute_transform.hpp>
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#include <boost/spirit/home/qi/domain.hpp>
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#include <boost/spirit/home/qi/detail/assign_to.hpp>
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#include <boost/optional.hpp>
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#include <vector>
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namespace boost { namespace spirit { namespace qi
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{
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struct optional
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{
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template <typename T>
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struct build_attribute_container
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{
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typedef boost::optional<T> type;
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};
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template <typename Component, typename Context, typename Iterator>
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struct attribute :
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build_container<optional, Component, Iterator, Context>
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{
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};
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template <
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typename Component
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, typename Iterator, typename Context
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, typename Skipper, typename Attribute>
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static bool parse(
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Component const& component
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, Iterator& first, Iterator const& last
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, Context& context, Skipper const& skipper
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, Attribute& attr)
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{
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typedef typename
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result_of::subject<Component>::type
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subject_type;
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typedef typename
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traits::attribute_of<
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qi::domain, subject_type, Context, Iterator>::type
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attr_type;
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typedef typename subject_type::director director;
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// create a value if Attribute is not unused_type
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typename mpl::if_<
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is_same<typename remove_const<Attribute>::type, unused_type>
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, unused_type
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, attr_type>::type
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val;
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if (director::parse(
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subject(component), first, last, context, skipper, val))
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{
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qi::detail::assign_to(val, attr);
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}
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return true;
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}
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template <typename Component, typename Context>
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static std::string what(Component const& component, Context const& ctx)
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{
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std::string result = "optional[";
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typedef typename
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result_of::subject<Component>::type::director
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director;
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result += director::what(subject(component), ctx);
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result += "]";
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return result;
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}
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};
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}}}
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#endif
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