| /*============================================================================= |
| 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 |
| |
| #if defined(_MSC_VER) |
| #pragma once |
| #endif |
| |
| #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 |