/Src/Dependencies/Boost/boost/multi_index/identity.hpp
http://hadesmem.googlecode.com/ · C++ Header · 147 lines · 90 code · 31 blank · 26 comment · 0 complexity · 16521f3016d8e47ded5a6c8cfd578455 MD5 · raw file
- /* Copyright 2003-2008 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)&&(_MSC_VER>=1200)
- #pragma once
- #endif
- #include <boost/config.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 auto_ptr<Type*>.)
- */
- /* NB. Some overloads of operator() have an extra dummy parameter int=0.
- * This disambiguator serves several purposes:
- * - Without it, MSVC++ 6.0 incorrectly regards some overloads as
- * specializations of a previous member function template.
- * - MSVC++ 6.0/7.0 seem to incorrectly treat some different memfuns
- * as if they have the same signature.
- * - If remove_const is broken due to lack of PTS, int=0 avoids the
- * declaration of memfuns with identical signature.
- */
- 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,int=0)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,int=0)const
- {
- return x;
- }
- Type& operator()(Type& x)const
- {
- return x;
- }
- const Type& operator()(const reference_wrapper<const Type>& x,int=0)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