146 lines
3.1 KiB
C++
146 lines
3.1 KiB
C++
|
/* Copyright 2003-2015 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_IDENTITY_HPP
|
||
|
|
#define BOOST_MULTI_INDEX_IDENTITY_HPP
|
||
|
|
|
||
|
|
#if defined(_MSC_VER)
|
||
|
|
#pragma once
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#include <boost/config.hpp>
|
||
|
|
#include <boost/detail/workaround.hpp>
|
||
|
|
#include <boost/mpl/if.hpp>
|
||
|
|
#include <boost/multi_index/identity_fwd.hpp>
|
||
|
|
#include <boost/type_traits/is_const.hpp>
|
||
|
|
#include <boost/type_traits/remove_const.hpp>
|
||
|
|
#include <boost/utility/enable_if.hpp>
|
||
|
|
|
||
|
|
#if !defined(BOOST_NO_SFINAE)
|
||
|
|
#include <boost/type_traits/is_convertible.hpp>
|
||
|
|
#endif
|
||
|
|
|
||
|
|
namespace boost{
|
||
|
|
|
||
|
|
template<class Type> class reference_wrapper; /* fwd decl. */
|
||
|
|
|
||
|
|
namespace multi_index{
|
||
|
|
|
||
|
|
namespace detail{
|
||
|
|
|
||
|
|
/* identity is a do-nothing key extractor that returns the [const] Type&
|
||
|
|
* object passed.
|
||
|
|
* Additionally, identity is overloaded to support referece_wrappers
|
||
|
|
* of Type and "chained pointers" to Type's. By chained pointer to Type we
|
||
|
|
* mean a type P such that, given a p of type P
|
||
|
|
* *...n...*x is convertible to Type&, for some n>=1.
|
||
|
|
* Examples of chained pointers are raw and smart pointers, iterators and
|
||
|
|
* arbitrary combinations of these (vg. Type** or unique_ptr<Type*>.)
|
||
|
|
*/
|
||
|
|
|
||
|
|
template<typename Type>
|
||
|
|
struct const_identity_base
|
||
|
|
{
|
||
|
|
typedef Type result_type;
|
||
|
|
|
||
|
|
template<typename ChainedPtr>
|
||
|
|
|
||
|
|
#if !defined(BOOST_NO_SFINAE)
|
||
|
|
typename disable_if<is_convertible<const ChainedPtr&,Type&>,Type&>::type
|
||
|
|
#else
|
||
|
|
Type&
|
||
|
|
#endif
|
||
|
|
|
||
|
|
operator()(const ChainedPtr& x)const
|
||
|
|
{
|
||
|
|
return operator()(*x);
|
||
|
|
}
|
||
|
|
|
||
|
|
Type& operator()(Type& x)const
|
||
|
|
{
|
||
|
|
return x;
|
||
|
|
}
|
||
|
|
|
||
|
|
Type& operator()(const reference_wrapper<Type>& x)const
|
||
|
|
{
|
||
|
|
return x.get();
|
||
|
|
}
|
||
|
|
|
||
|
|
Type& operator()(
|
||
|
|
const reference_wrapper<typename remove_const<Type>::type>& x
|
||
|
|
|
||
|
|
#if BOOST_WORKAROUND(BOOST_MSVC,==1310)
|
||
|
|
/* http://lists.boost.org/Archives/boost/2015/10/226135.php */
|
||
|
|
,int=0
|
||
|
|
#endif
|
||
|
|
|
||
|
|
)const
|
||
|
|
{
|
||
|
|
return x.get();
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
template<typename Type>
|
||
|
|
struct non_const_identity_base
|
||
|
|
{
|
||
|
|
typedef Type result_type;
|
||
|
|
|
||
|
|
/* templatized for pointer-like types */
|
||
|
|
|
||
|
|
template<typename ChainedPtr>
|
||
|
|
|
||
|
|
#if !defined(BOOST_NO_SFINAE)
|
||
|
|
typename disable_if<
|
||
|
|
is_convertible<const ChainedPtr&,const Type&>,Type&>::type
|
||
|
|
#else
|
||
|
|
Type&
|
||
|
|
#endif
|
||
|
|
|
||
|
|
operator()(const ChainedPtr& x)const
|
||
|
|
{
|
||
|
|
return operator()(*x);
|
||
|
|
}
|
||
|
|
|
||
|
|
const Type& operator()(const Type& x)const
|
||
|
|
{
|
||
|
|
return x;
|
||
|
|
}
|
||
|
|
|
||
|
|
Type& operator()(Type& x)const
|
||
|
|
{
|
||
|
|
return x;
|
||
|
|
}
|
||
|
|
|
||
|
|
const Type& operator()(const reference_wrapper<const Type>& x)const
|
||
|
|
{
|
||
|
|
return x.get();
|
||
|
|
}
|
||
|
|
|
||
|
|
Type& operator()(const reference_wrapper<Type>& x)const
|
||
|
|
{
|
||
|
|
return x.get();
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
} /* namespace multi_index::detail */
|
||
|
|
|
||
|
|
template<class Type>
|
||
|
|
struct identity:
|
||
|
|
mpl::if_c<
|
||
|
|
is_const<Type>::value,
|
||
|
|
detail::const_identity_base<Type>,detail::non_const_identity_base<Type>
|
||
|
|
>::type
|
||
|
|
{
|
||
|
|
};
|
||
|
|
|
||
|
|
} /* namespace multi_index */
|
||
|
|
|
||
|
|
} /* namespace boost */
|
||
|
|
|
||
|
|
#endif
|