Chris@101: /* Copyright 2006-2014 Joaquin M Lopez Munoz.
Chris@16:  * Distributed under the Boost Software License, Version 1.0.
Chris@16:  * (See accompanying file LICENSE_1_0.txt or copy at
Chris@16:  * http://www.boost.org/LICENSE_1_0.txt)
Chris@16:  *
Chris@16:  * See http://www.boost.org/libs/flyweight for library home page.
Chris@16:  */
Chris@16: 
Chris@101: #ifndef BOOST_FLYWEIGHT_DETAIL_PERFECT_FWD_HPP
Chris@101: #define BOOST_FLYWEIGHT_DETAIL_PERFECT_FWD_HPP
Chris@101: 
Chris@101: #if defined(_MSC_VER)
Chris@101: #pragma once
Chris@101: #endif
Chris@101: 
Chris@101: /* C++03-compatible implementation of perfect forwarding.
Chris@101:  * Usage:
Chris@101:  *
Chris@101:  *  # define NAME ...
Chris@101:  *  # define BODY(args) {...BOOST_FLYWEIGHT_FORWARD(args)...}
Chris@101:  *  BOOST_FLYWEIGHT_PERFECT_FWD(name,body)
Chris@101:  *
Chris@101:  * where NAME includes the return type and qualifiers (if any) and BODY(args)
Chris@101:  * is expected to fo the forwarding through BOOST_FLYWEIGHT_FORWARD(args).
Chris@101:  *
Chris@101:  * In compilers capable of perfect forwarding, the real thing is provided
Chris@101:  * (just one variadic args overload is generated). Otherwise the machinery
Chris@101:  * generates n+1 overloads, if rvalue refs are supported, or else 2^(n+1)-1
Chris@101:  * overloads accepting any combination of lvalue refs and const lvalue refs,
Chris@101:  * up to BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS args.
Chris@101:  *
Chris@101:  * BOOST_FLYWEIGHT_PERFECT_FWD_WITH_ARGS(name,body) is a variation omitting the
Chris@101:  * overloads with zero args --when perfect forwarding is available, this second
Chris@101:  * macro is exactly the same as the original. 
Chris@16:  */
Chris@16: 
Chris@101: #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
Chris@101: #include <boost/preprocessor/cat.hpp>
Chris@101: #include <boost/preprocessor/repetition/enum.hpp>
Chris@101: #include <boost/preprocessor/repetition/enum_params.hpp>
Chris@101: #include <boost/preprocessor/seq/seq.hpp>
Chris@101: 
Chris@101: #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
Chris@101: #include <utility>
Chris@101: #endif
Chris@101: 
Chris@101: #define BOOST_FLYWEIGHT_FORWARD_FORWARD_AUX(z,n,_) \
Chris@101: std::forward<BOOST_PP_CAT(T,n)>(BOOST_PP_CAT(t,n))
Chris@101: 
Chris@101: #define BOOST_FLYWEIGHT_FORWARD_FORWARD(n) \
Chris@101: BOOST_PP_ENUM(n,BOOST_FLYWEIGHT_FORWARD_FORWARD_AUX,~)
Chris@101: 
Chris@101: #define BOOST_FLYWEIGHT_FORWARD_ENUM(n) BOOST_PP_ENUM_PARAMS(n,t)
Chris@101: 
Chris@101: #define BOOST_FLYWEIGHT_FORWARD_PASS(arg) arg
Chris@101: 
Chris@101: #define BOOST_FLYWEIGHT_FORWARD(args)\
Chris@101: BOOST_PP_CAT(BOOST_FLYWEIGHT_FORWARD_,BOOST_PP_SEQ_HEAD(args))( \
Chris@101: BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(args)))
Chris@101: 
Chris@101: #if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)||\
Chris@101:     defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
Chris@16: 
Chris@16: #if !defined(BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS)
Chris@16: #define BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS 5
Chris@16: #endif
Chris@16: 
Chris@101: #if BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS<0
Chris@101: #error BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS must be >=0
Chris@101: #endif
Chris@101: 
Chris@16: #if BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS<=5
Chris@16: #include <boost/flyweight/detail/pp_perfect_fwd.hpp>
Chris@16: #else
Chris@16: #include <boost/flyweight/detail/dyn_perfect_fwd.hpp>
Chris@16: #endif
Chris@101: 
Chris@101: #else
Chris@101: 
Chris@101: /* real perfect forwarding */
Chris@101: 
Chris@101: #define BOOST_FLYWEIGHT_PERFECT_FWD(name,body) \
Chris@101: template<typename... Args>name(Args&&... args) \
Chris@101: body((PASS)(std::forward<Args>(args)...))
Chris@101: 
Chris@101: #define BOOST_FLYWEIGHT_PERFECT_FWD_WITH_ARGS  \
Chris@101: BOOST_FLYWEIGHT_PERFECT_FWD
Chris@101: 
Chris@101: #endif
Chris@101: #endif