/*=============================================================================
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Copyright (c) 2001-2014 Joel de Guzman
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Copyright (c) 2013 Agustin Berge
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http://spirit.sourceforge.net/
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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(BOOST_SPIRIT_X3_ATTRIBUTE_OF_JAN_7_2012_0914AM)
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#define BOOST_SPIRIT_X3_ATTRIBUTE_OF_JAN_7_2012_0914AM
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#include <boost/spirit/home/x3/support/utility/sfinae.hpp>
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#include <boost/mpl/identity.hpp>
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#include <boost/utility/enable_if.hpp>
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namespace boost { namespace spirit { namespace x3 { namespace traits
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{
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///////////////////////////////////////////////////////////////////////////
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// Get the attribute type of a component. By default, this gets the
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// Component's attribute_type typedef or instantiates a nested attribute
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// metafunction. Components may specialize this if such an attribute_type
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// is not readily available (e.g. expensive to compute at compile time).
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///////////////////////////////////////////////////////////////////////////
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template <typename Component, typename Context, typename Enable = void>
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struct attribute_of;
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namespace detail
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{
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template <typename Component, typename Context, typename Enable = void>
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struct default_attribute_of;
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template <typename Component, typename Context>
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struct default_attribute_of<Component, Context,
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typename disable_if_substitution_failure<
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typename Component::attribute_type>::type>
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: mpl::identity<typename Component::attribute_type> {};
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template <typename Component, typename Context>
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struct default_attribute_of<Component, Context,
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typename disable_if_substitution_failure<
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typename Component::template attribute<Context>::type>::type>
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: Component::template attribute<Context> {};
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template <typename Component, typename Context>
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struct default_attribute_of<Component, Context,
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typename enable_if_c<Component::is_pass_through_unary>::type>
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: attribute_of<typename Component::subject_type, Context>{};
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}
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template <typename Component, typename Context, typename Enable>
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struct attribute_of : detail::default_attribute_of<Component, Context> {};
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}}}}
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#endif
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