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/* Copyright 2003-2013 Joaquin M Lopez Munoz.
* 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)
*
* See http://www.boost.org/libs/multi_index for library home page.
*/
#ifndef BOOST_MULTI_INDEX_GLOBAL_FUN_HPP
#define BOOST_MULTI_INDEX_GLOBAL_FUN_HPP
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
#include <boost/mpl/if.hpp>
#include <boost/type_traits/is_const.hpp>
#include <boost/type_traits/is_reference.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/utility/enable_if.hpp>
#if !defined(BOOST_NO_SFINAE)
#include <boost/type_traits/is_convertible.hpp>
#endif
namespace boost{
template<class T> class reference_wrapper; /* fwd decl. */
namespace multi_index{
namespace detail{
/* global_fun is a read-only key extractor from Value based on a given global
* (or static member) function with signature:
*
* Type f([const] Value [&]);
*
* Additionally, global_fun and const_global_fun are overloaded to support
* referece_wrappers of Value and "chained pointers" to Value's. By chained
* pointer to T we mean a type P such that, given a p of Type P
* *...n...*x is convertible to T&, for some n>=1.
* Examples of chained pointers are raw and smart pointers, iterators and
* arbitrary combinations of these (vg. T** or auto_ptr<T*>.)
*/
template<class Value,typename Type,Type (*PtrToFunction)(Value)>
struct const_ref_global_fun_base
{
typedef typename remove_reference<Type>::type result_type;
template<typename ChainedPtr>
#if !defined(BOOST_NO_SFINAE)
typename disable_if<
is_convertible<const ChainedPtr&,Value>,Type>::type
#else
Type
#endif
operator()(const ChainedPtr& x)const
{
return operator()(*x);
}
Type operator()(Value x)const
{
return PtrToFunction(x);
}
Type operator()(
const reference_wrapper<
typename remove_reference<Value>::type>& x)const
{
return operator()(x.get());
}
Type operator()(
const reference_wrapper<
typename remove_const<
typename remove_reference<Value>::type>::type>& x)const
{
return operator()(x.get());
}
};
template<class Value,typename Type,Type (*PtrToFunction)(Value)>
struct non_const_ref_global_fun_base
{
typedef typename remove_reference<Type>::type result_type;
template<typename ChainedPtr>
#if !defined(BOOST_NO_SFINAE)
typename disable_if<
is_convertible<ChainedPtr&,Value>,Type>::type
#else
Type
#endif
operator()(const ChainedPtr& x)const
{
return operator()(*x);
}
Type operator()(Value x)const
{
return PtrToFunction(x);
}
Type operator()(
const reference_wrapper<
typename remove_reference<Value>::type>& x)const
{
return operator()(x.get());
}
};
template<class Value,typename Type,Type (*PtrToFunction)(Value)>
struct non_ref_global_fun_base
{
typedef typename remove_reference<Type>::type result_type;
template<typename ChainedPtr>
#if !defined(BOOST_NO_SFINAE)
typename disable_if<
is_convertible<const ChainedPtr&,const Value&>,Type>::type
#else
Type
#endif
operator()(const ChainedPtr& x)const
{
return operator()(*x);
}
Type operator()(const Value& x)const
{
return PtrToFunction(x);
}
Type operator()(const reference_wrapper<const Value>& x)const
{
return operator()(x.get());
}
Type operator()(
const reference_wrapper<typename remove_const<Value>::type>& x)const
{
return operator()(x.get());
}
};
} /* namespace multi_index::detail */
template<class Value,typename Type,Type (*PtrToFunction)(Value)>
struct global_fun:
mpl::if_c<
is_reference<Value>::value,
typename mpl::if_c<
is_const<typename remove_reference<Value>::type>::value,
detail::const_ref_global_fun_base<Value,Type,PtrToFunction>,
detail::non_const_ref_global_fun_base<Value,Type,PtrToFunction>
>::type,
detail::non_ref_global_fun_base<Value,Type,PtrToFunction>
>::type
{
};
} /* namespace multi_index */
} /* namespace boost */
#endif
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