williamr@2: #ifndef BOOST_PFTO_HPP
williamr@2: #define BOOST_PFTO_HPP
williamr@2: 
williamr@2: // MS compatible compilers support #pragma once
williamr@2: #if defined(_MSC_VER) && (_MSC_VER >= 1020)
williamr@2: # pragma once
williamr@2: #endif
williamr@2: 
williamr@2: /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
williamr@2: // pfto.hpp: workarounds for compilers which have problems supporting
williamr@2: // Partial Function Template Ordering (PFTO).
williamr@2: 
williamr@2: // (C) Copyright 2002 Robert Ramey - http://www.rrsd.com . 
williamr@2: // Use, modification and distribution is subject to the Boost Software
williamr@2: // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: //  See http://www.boost.org for updates, documentation, and revision history.
williamr@2: // PFTO version is used to specify the last argument of certain functions
williamr@2: // Function it is used to support  compilers that fail to support correct Partial 
williamr@2: // Template Ordering
williamr@2: #include <boost/config.hpp>
williamr@2: 
williamr@2: // some compilers can use an exta argument and use function overloading
williamr@2: // to choose desired function.  This extra argument is long in the default
williamr@2: // function implementation and int for the rest.  The function is called
williamr@2: // with an int argument.  This first attempts to match functions with an
williamr@2: // int argument before the default one (with a long argument).  This is
williamr@2: // known to function with VC 6.0. On other compilers this fails (Borland)
williamr@2: // or causes other problems (GCC).  note: this 
williamr@2: 
williamr@2: #if defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
williamr@2:     #define BOOST_PFTO long
williamr@2: #else
williamr@2:     #define BOOST_PFTO
williamr@2: #endif
williamr@2: 
williamr@2: // here's another approach.  Rather than use a default function - make sure
williamr@2: // there is no default at all by requiring that all function invocations
williamr@2: // have a "wrapped" argument type.  This solves a problem with VC 6.0
williamr@2: // (and perhaps others) while implementing templated constructors.
williamr@2: 
williamr@2: namespace boost {
williamr@2: 
williamr@2: template<class T>
williamr@2: struct pfto_wrapper {
williamr@2:     const T & t;
williamr@2:     operator const T & (){
williamr@2:         return t;
williamr@2:     }
williamr@2:     pfto_wrapper (const T & rhs) : t(rhs) {}
williamr@2: };
williamr@2: 
williamr@2: template<class T>
williamr@2: pfto_wrapper<T> make_pfto_wrapper(const T & t, BOOST_PFTO int){
williamr@2:     return pfto_wrapper<T>(t);
williamr@2: }
williamr@2: 
williamr@2: template<class T>
williamr@2: pfto_wrapper<T> make_pfto_wrapper(const pfto_wrapper<T> & t, int){
williamr@2:     return t;
williamr@2: }
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #ifdef BOOST_NO_FUNCTION_TEMPLATE_ORDERING
williamr@2:     #define BOOST_PFTO_WRAPPER(T) boost::pfto_wrapper<T>
williamr@2:     #define BOOST_MAKE_PFTO_WRAPPER(t) boost::make_pfto_wrapper(t, 0)
williamr@2: #else
williamr@2:     #define BOOST_PFTO_WRAPPER(T) T
williamr@2:     #define BOOST_MAKE_PFTO_WRAPPER(t) t
williamr@2: #endif
williamr@2: 
williamr@2: #endif // BOOST_PFTO_HPP