118 lines
3.0 KiB
Plaintext
118 lines
3.0 KiB
Plaintext
|
//-----------------------------------------------------------------------------
|
||
|
|
// 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/throw_exception.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) BOOST_NOEXCEPT
|
||
|
|
: visitor_(visitor)
|
||
|
|
{
|
||
|
|
}
|
||
|
|
|
||
|
|
public: // static visitor interfaces
|
||
|
|
|
||
|
|
template <typename U>
|
||
|
|
result_type operator()(const U&) const
|
||
|
|
{
|
||
|
|
boost::throw_exception(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
|