| /*============================================================================= |
| 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) |
| ==============================================================================*/ |
| #ifndef PHOENIX_CORE_VALUE_HPP |
| #define PHOENIX_CORE_VALUE_HPP |
| |
| #include <boost/spirit/home/phoenix/core/actor.hpp> |
| #include <boost/spirit/home/phoenix/core/as_actor.hpp> |
| #include <boost/static_assert.hpp> |
| |
| #include <boost/type_traits/is_reference.hpp> |
| #include <boost/type_traits/remove_reference.hpp> |
| #include <boost/type_traits/is_pointer.hpp> |
| #include <boost/type_traits/add_const.hpp> |
| #include <boost/type_traits/add_reference.hpp> |
| #include <boost/type_traits/remove_pointer.hpp> |
| #include <boost/type_traits/is_function.hpp> |
| |
| #include <boost/mpl/bool.hpp> |
| #include <boost/mpl/eval_if.hpp> |
| #include <boost/mpl/identity.hpp> |
| |
| namespace boost { namespace phoenix |
| { |
| namespace meta |
| { |
| template<typename T> |
| struct const_ref |
| : add_reference<typename add_const<T>::type> |
| {}; |
| |
| template<typename T> |
| struct argument_type |
| : mpl::eval_if< |
| is_function<typename remove_pointer<T>::type>, |
| mpl::identity<T>, |
| const_ref<T> > |
| { |
| typedef T type; |
| }; |
| } |
| |
| template <typename T> |
| struct value |
| { |
| BOOST_STATIC_ASSERT( |
| mpl::not_<is_reference<T> >::value != 0); |
| |
| typedef mpl::false_ no_nullary; |
| |
| template <typename Env> |
| struct result |
| { |
| typedef T type; |
| }; |
| |
| value(T const& arg) |
| : val(arg) {} |
| |
| template <typename Env> |
| T const& |
| eval(Env const&) const |
| { |
| return val; |
| } |
| |
| T val; |
| }; |
| |
| template <typename Actor> |
| struct actor_value |
| { |
| typedef typename Actor::no_nullary no_nullary; |
| |
| template <typename Env> |
| struct result |
| { |
| typedef typename |
| remove_reference< |
| typename eval_result<Actor, Env>::type |
| >::type |
| type; |
| }; |
| |
| actor_value(Actor const& actor) |
| : actor(actor) {} |
| |
| template <typename Env> |
| typename result<Env>::type |
| eval(Env const& env) const |
| { |
| return actor.eval(env); |
| } |
| |
| Actor actor; |
| }; |
| |
| template <typename T> |
| inline typename as_actor<T>::type |
| val(T const& v) |
| { |
| return as_actor<T>::convert(v); |
| } |
| |
| template <typename Derived> |
| inline actor<actor_value<Derived> > |
| val(actor<Derived> const& actor) |
| { |
| return actor_value<Derived>(actor); |
| } |
| |
| template <typename T> |
| struct as_actor_base |
| { |
| typedef value<T> type; |
| |
| static value<T> |
| convert(typename meta::argument_type<T>::type x) |
| { |
| return value<T>(x); |
| } |
| }; |
| |
| // Sometimes it is necessary to auto-convert references to |
| // a value<T>. This happens when we are re-currying. This |
| // cannot happen through the standard public actor interfaces. |
| template <typename T> |
| struct as_actor_base<T&> |
| { |
| typedef value<T> type; |
| |
| static value<T> |
| convert(T& x) |
| { |
| return value<T>(x); |
| } |
| }; |
| |
| template <typename T, int N> |
| struct as_actor_base<T[N]> |
| { |
| typedef value<T const*> type; |
| |
| static value<T const*> |
| convert(T const x[N]) |
| { |
| return value<T const*>(x); |
| } |
| }; |
| }} |
| |
| #endif |