//----------------------------------------------------------------------------- | |
// 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 |