| //----------------------------------------------------------------------------- |
| // boost variant/visitor_ptr.hpp header file |
| // See http://www.boost.org for updates, documentation, and revision history. |
| //----------------------------------------------------------------------------- |
| // |
| // Copyright (c) 2002-2003 |
| // Eric Friedman |
| // |
| // 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 BOOST_VARIANT_VISITOR_PTR_HPP |
| #define BOOST_VARIANT_VISITOR_PTR_HPP |
| |
| #include "boost/variant/bad_visit.hpp" |
| #include "boost/variant/static_visitor.hpp" |
| |
| #include "boost/mpl/eval_if.hpp" |
| #include "boost/mpl/identity.hpp" |
| #include "boost/type_traits/add_reference.hpp" |
| #include "boost/type_traits/is_reference.hpp" |
| #include "boost/type_traits/is_void.hpp" |
| |
| namespace boost { |
| |
| ////////////////////////////////////////////////////////////////////////// |
| // function template visitor_ptr |
| // |
| // Adapts a function pointer for use as visitor capable of handling |
| // values of a single type. Throws bad_visit if inappropriately applied. |
| // |
| template <typename T, typename R> |
| class visitor_ptr_t |
| : public static_visitor<R> |
| { |
| private: // representation |
| |
| typedef R (*visitor_t)(T); |
| |
| visitor_t visitor_; |
| |
| public: // typedefs |
| |
| typedef R result_type; |
| |
| private: // private typedefs |
| |
| typedef typename mpl::eval_if< |
| is_reference<T> |
| , mpl::identity<T> |
| , add_reference<const T> |
| >::type argument_fwd_type; |
| |
| public: // structors |
| |
| explicit visitor_ptr_t(visitor_t visitor) |
| : visitor_(visitor) |
| { |
| } |
| |
| public: // static visitor interfaces |
| |
| template <typename U> |
| result_type operator()(const U&) const |
| { |
| throw bad_visit(); |
| } |
| |
| #if !defined(BOOST_NO_VOID_RETURNS) |
| |
| public: // static visitor interfaces, cont. |
| |
| result_type operator()(argument_fwd_type operand) const |
| { |
| return visitor_(operand); |
| } |
| |
| #else // defined(BOOST_NO_VOID_RETURNS) |
| |
| private: // helpers, for static visitor interfaces (below) |
| |
| result_type execute_impl(argument_fwd_type operand, mpl::false_) const |
| { |
| return visitor_(operand); |
| } |
| |
| BOOST_VARIANT_AUX_RETURN_VOID_TYPE |
| execute_impl(argument_fwd_type operand, mpl::true_) const |
| { |
| visitor_(operand); |
| BOOST_VARIANT_AUX_RETURN_VOID; |
| } |
| |
| public: // static visitor interfaces, cont. |
| |
| BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type) |
| operator()(argument_fwd_type operand) const |
| { |
| typedef typename is_void<result_type>::type has_void_result; |
| return execute_impl(operand, has_void_result()); |
| } |
| |
| #endif // BOOST_NO_VOID_RETURNS workaround |
| |
| }; |
| |
| template <typename R, typename T> |
| inline visitor_ptr_t<T,R> visitor_ptr(R (*visitor)(T)) |
| { |
| return visitor_ptr_t<T,R>(visitor); |
| } |
| |
| } // namespace boost |
| |
| #endif// BOOST_VISITOR_VISITOR_PTR_HPP |