comparison DEPENDENCIES/generic/include/boost/flyweight/detail/perfect_fwd.hpp @ 101:c530137014c0

Update Boost headers (1.58.0)

-/* Copyright 2006-2008 Joaquin M Lopez Munoz.
+/* Copyright 2006-2014 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/flyweight for library home page.
  */
 
-/* Brute force implementation of perfect forwarding overloads.
- * Usage: include after having defined the argument macros:
- *   BOOST_FLYWEIGHT_PERFECT_FWD_NAME
- *   BOOST_FLYWEIGHT_PERFECT_FWD_BODY
+#ifndef BOOST_FLYWEIGHT_DETAIL_PERFECT_FWD_HPP
+#define BOOST_FLYWEIGHT_DETAIL_PERFECT_FWD_HPP
+
+#if defined(_MSC_VER)
+#pragma once
+#endif
+
+/* C++03-compatible implementation of perfect forwarding.
+ * Usage:
+ *
+ *  # define NAME ...
+ *  # define BODY(args) {...BOOST_FLYWEIGHT_FORWARD(args)...}
+ *  BOOST_FLYWEIGHT_PERFECT_FWD(name,body)
+ *
+ * where NAME includes the return type and qualifiers (if any) and BODY(args)
+ * is expected to fo the forwarding through BOOST_FLYWEIGHT_FORWARD(args).
+ *
+ * In compilers capable of perfect forwarding, the real thing is provided
+ * (just one variadic args overload is generated). Otherwise the machinery
+ * generates n+1 overloads, if rvalue refs are supported, or else 2^(n+1)-1
+ * overloads accepting any combination of lvalue refs and const lvalue refs,
+ * up to BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS args.
+ *
+ * BOOST_FLYWEIGHT_PERFECT_FWD_WITH_ARGS(name,body) is a variation omitting the
+ * overloads with zero args --when perfect forwarding is available, this second
+ * macro is exactly the same as the original. 
  */
 
-/* This user_definable macro limits the maximum number of arguments to
- * be perfect forwarded. Beware combinatorial explosion: manual perfect
- * forwarding for n arguments produces 2^n distinct overloads.
- */
+#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
+#include <boost/preprocessor/cat.hpp>
+#include <boost/preprocessor/repetition/enum.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/seq/seq.hpp>
+
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+#include <utility>
+#endif
+
+#define BOOST_FLYWEIGHT_FORWARD_FORWARD_AUX(z,n,_) \
+std::forward<BOOST_PP_CAT(T,n)>(BOOST_PP_CAT(t,n))
+
+#define BOOST_FLYWEIGHT_FORWARD_FORWARD(n) \
+BOOST_PP_ENUM(n,BOOST_FLYWEIGHT_FORWARD_FORWARD_AUX,~)
+
+#define BOOST_FLYWEIGHT_FORWARD_ENUM(n) BOOST_PP_ENUM_PARAMS(n,t)
+
+#define BOOST_FLYWEIGHT_FORWARD_PASS(arg) arg
+
+#define BOOST_FLYWEIGHT_FORWARD(args)\
+BOOST_PP_CAT(BOOST_FLYWEIGHT_FORWARD_,BOOST_PP_SEQ_HEAD(args))( \
+BOOST_PP_SEQ_HEAD(BOOST_PP_SEQ_TAIL(args)))
+
+#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)||\
+    defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 
 #if !defined(BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS)
 #define BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS 5
+#endif
+
+#if BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS<0
+#error BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS must be >=0
 #endif
 
 #if BOOST_FLYWEIGHT_LIMIT_PERFECT_FWD_ARGS<=5
 #include <boost/flyweight/detail/pp_perfect_fwd.hpp>
 #else
 #include <boost/flyweight/detail/dyn_perfect_fwd.hpp>
 #endif
+
+#else
+
+/* real perfect forwarding */
+
+#define BOOST_FLYWEIGHT_PERFECT_FWD(name,body) \
+template<typename... Args>name(Args&&... args) \
+body((PASS)(std::forward<Args>(args)...))
+
+#define BOOST_FLYWEIGHT_PERFECT_FWD_WITH_ARGS  \
+BOOST_FLYWEIGHT_PERFECT_FWD
+
+#endif
+#endif