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