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1 #ifndef BOOST_PFTO_HPP |
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2 #define BOOST_PFTO_HPP |
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3 |
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4 // MS compatible compilers support #pragma once |
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5 #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
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6 # pragma once |
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7 #endif |
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8 |
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9 /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8 |
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10 // pfto.hpp: workarounds for compilers which have problems supporting |
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11 // Partial Function Template Ordering (PFTO). |
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12 |
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13 // (C) Copyright 2002 Robert Ramey - http://www.rrsd.com . |
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14 // Use, modification and distribution is subject to the Boost Software |
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15 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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16 // http://www.boost.org/LICENSE_1_0.txt) |
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17 |
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18 // See http://www.boost.org for updates, documentation, and revision history. |
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19 // PFTO version is used to specify the last argument of certain functions |
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20 // Function it is used to support compilers that fail to support correct Partial |
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21 // Template Ordering |
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22 #include <boost/config.hpp> |
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23 |
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24 // some compilers can use an exta argument and use function overloading |
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25 // to choose desired function. This extra argument is long in the default |
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26 // function implementation and int for the rest. The function is called |
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27 // with an int argument. This first attempts to match functions with an |
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28 // int argument before the default one (with a long argument). This is |
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29 // known to function with VC 6.0. On other compilers this fails (Borland) |
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30 // or causes other problems (GCC). note: this |
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31 |
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32 #if defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING) |
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33 #define BOOST_PFTO long |
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34 #else |
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35 #define BOOST_PFTO |
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36 #endif |
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37 |
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38 // here's another approach. Rather than use a default function - make sure |
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39 // there is no default at all by requiring that all function invocations |
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40 // have a "wrapped" argument type. This solves a problem with VC 6.0 |
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41 // (and perhaps others) while implementing templated constructors. |
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42 |
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43 namespace boost { |
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44 |
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45 template<class T> |
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46 struct pfto_wrapper { |
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47 const T & t; |
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48 operator const T & (){ |
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49 return t; |
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50 } |
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51 pfto_wrapper (const T & rhs) : t(rhs) {} |
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52 }; |
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53 |
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54 template<class T> |
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55 pfto_wrapper<T> make_pfto_wrapper(const T & t, BOOST_PFTO int){ |
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56 return pfto_wrapper<T>(t); |
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57 } |
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58 |
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59 template<class T> |
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60 pfto_wrapper<T> make_pfto_wrapper(const pfto_wrapper<T> & t, int){ |
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61 return t; |
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62 } |
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63 |
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64 } // namespace boost |
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65 |
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66 #ifdef BOOST_NO_FUNCTION_TEMPLATE_ORDERING |
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67 #define BOOST_PFTO_WRAPPER(T) boost::pfto_wrapper<T> |
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68 #define BOOST_MAKE_PFTO_WRAPPER(t) boost::make_pfto_wrapper(t, 0) |
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69 #else |
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70 #define BOOST_PFTO_WRAPPER(T) T |
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71 #define BOOST_MAKE_PFTO_WRAPPER(t) t |
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72 #endif |
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73 |
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74 #endif // BOOST_PFTO_HPP |