| /*============================================================================= |
| Copyright (c) 2001-2007 Joel de Guzman |
| |
| 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_EXPAND_ARG_FEB_19_2007_1107AM) |
| #define BOOST_SPIRIT_EXPAND_ARG_FEB_19_2007_1107AM |
| |
| #include <boost/mpl/bool.hpp> |
| #include <boost/mpl/identity.hpp> |
| #include <boost/mpl/eval_if.hpp> |
| #include <boost/utility/result_of.hpp> |
| #include <boost/type_traits/is_scalar.hpp> |
| #include <boost/variant.hpp> |
| |
| namespace boost { namespace spirit { namespace detail |
| { |
| /////////////////////////////////////////////////////////////////////////// |
| template <typename Context> |
| struct expand_arg |
| { |
| template <typename T> |
| struct result_type |
| { |
| typedef typename |
| mpl::eval_if< |
| is_scalar<T> |
| , mpl::identity<T const &> |
| , boost::result_of<T(unused_type, Context)> |
| >::type |
| type; |
| }; |
| |
| template <typename T> |
| struct result; |
| |
| template <typename F, typename A0> |
| struct result<F(A0)> |
| : result_type<A0> {}; |
| |
| template <typename F, typename A0> |
| struct result<F(A0&)> |
| : result_type<A0> {}; |
| |
| expand_arg(Context& context) |
| : context(context) |
| { |
| } |
| |
| template <typename T> |
| typename result_type<T>::type |
| call(T const& f, mpl::false_) const |
| { |
| return f(unused, context); |
| } |
| |
| template <typename T> |
| typename result_type<T>::type |
| call(T const& val, mpl::true_) const |
| { |
| return val; |
| } |
| |
| template <typename T> |
| typename result_type<T>::type |
| operator()(T const& x) const |
| { |
| return call(x, is_scalar<T>()); |
| } |
| |
| Context& context; |
| }; |
| |
| }}} |
| |
| #endif |
