81 lines
2.7 KiB
C++
81 lines
2.7 KiB
C++
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// Copyright (c) 2001-2011 Hartmut Kaiser
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// Copyright (c) 2001-2011 Joel de Guzman
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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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#ifndef BOOST_SPIRIT_KARMA_DETAIL_ATTRIBUTES_HPP
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#define BOOST_SPIRIT_KARMA_DETAIL_ATTRIBUTES_HPP
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#include <boost/spirit/home/karma/domain.hpp>
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#include <boost/spirit/home/support/attributes_fwd.hpp>
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#include <boost/spirit/home/support/attributes.hpp>
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///////////////////////////////////////////////////////////////////////////////
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namespace boost { namespace spirit { namespace karma
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{
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template <typename Exposed, typename Transformed, typename Enable = void>
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struct transform_attribute
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{
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typedef Transformed type;
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static Transformed pre(Exposed& val)
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{
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return Transformed(traits::extract_from<Transformed>(val, unused));
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}
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// Karma only, no post() and no fail() required
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};
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template <typename Exposed, typename Transformed>
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struct transform_attribute<boost::optional<Exposed> const, Transformed
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, typename disable_if<is_same<boost::optional<Exposed>, Transformed> >::type>
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{
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typedef Transformed const& type;
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static Transformed const& pre(boost::optional<Exposed> const& val)
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{
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return boost::get<Transformed>(val);
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}
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};
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template <typename Attribute>
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struct transform_attribute<Attribute const, Attribute>
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{
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typedef Attribute const& type;
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static Attribute const& pre(Attribute const& val) { return val; }
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// Karma only, no post() and no fail() required
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};
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// unused_type needs some special handling as well
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template <>
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struct transform_attribute<unused_type, unused_type>
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{
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typedef unused_type type;
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static unused_type pre(unused_type) { return unused; }
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};
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template <>
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struct transform_attribute<unused_type const, unused_type>
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: transform_attribute<unused_type, unused_type>
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{};
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template <typename Attribute>
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struct transform_attribute<Attribute, unused_type>
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: transform_attribute<unused_type, unused_type>
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{};
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template <typename Attribute>
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struct transform_attribute<Attribute const, unused_type>
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: transform_attribute<unused_type, unused_type>
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{};
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}}}
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///////////////////////////////////////////////////////////////////////////////
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namespace boost { namespace spirit { namespace traits { namespace detail
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{
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template <typename Exposed, typename Transformed>
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struct transform_attribute_base<Exposed, Transformed, karma::domain>
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: karma::transform_attribute<Exposed, Transformed>
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{};
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}}}}
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#endif
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