| // Copyright 2005-2009 Daniel James. | |
| // 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) | |
| #if !defined(BOOST_FUNCTIONAL_HASH_DETAIL_FLOAT_FUNCTIONS_HPP) | |
| #define BOOST_FUNCTIONAL_HASH_DETAIL_FLOAT_FUNCTIONS_HPP | |
| #include <boost/config.hpp> | |
| #include <boost/config/no_tr1/cmath.hpp> | |
| #if defined(_MSC_VER) && (_MSC_VER >= 1020) | |
| # pragma once | |
| #endif | |
| // The C++ standard requires that the C float functions are overloarded | |
| // for float, double and long double in the std namespace, but some of the older | |
| // library implementations don't support this. On some that don't, the C99 | |
| // float functions (frexpf, frexpl, etc.) are available. | |
| // | |
| // The following tries to automatically detect which are available. | |
| namespace boost { | |
| namespace hash_detail { | |
| // Returned by dummy versions of the float functions. | |
| struct not_found { | |
| // Implicitly convertible to float and long double in order to avoid | |
| // a compile error when the dummy float functions are used. | |
| inline operator float() const { return 0; } | |
| inline operator long double() const { return 0; } | |
| }; | |
| // A type for detecting the return type of functions. | |
| template <typename T> struct is; | |
| template <> struct is<float> { char x[10]; }; | |
| template <> struct is<double> { char x[20]; }; | |
| template <> struct is<long double> { char x[30]; }; | |
| template <> struct is<boost::hash_detail::not_found> { char x[40]; }; | |
| // Used to convert the return type of a function to a type for sizeof. | |
| template <typename T> is<T> float_type(T); | |
| // call_ldexp | |
| // | |
| // This will get specialized for float and long double | |
| template <typename Float> struct call_ldexp | |
| { | |
| typedef double float_type; | |
| inline double operator()(double a, int b) const | |
| { | |
| using namespace std; | |
| return ldexp(a, b); | |
| } | |
| }; | |
| // call_frexp | |
| // | |
| // This will get specialized for float and long double | |
| template <typename Float> struct call_frexp | |
| { | |
| typedef double float_type; | |
| inline double operator()(double a, int* b) const | |
| { | |
| using namespace std; | |
| return frexp(a, b); | |
| } | |
| }; | |
| } | |
| } | |
| // A namespace for dummy functions to detect when the actual function we want | |
| // isn't available. ldexpl, ldexpf etc. might be added tby the macros below. | |
| // | |
| // AFAICT these have to be outside of the boost namespace, as if they're in | |
| // the boost namespace they'll always be preferable to any other function | |
| // (since the arguments are built in types, ADL can't be used). | |
| namespace boost_hash_detect_float_functions { | |
| template <class Float> boost::hash_detail::not_found ldexp(Float, int); | |
| template <class Float> boost::hash_detail::not_found frexp(Float, int*); | |
| } | |
| // Macros for generating specializations of call_ldexp and call_frexp. | |
| // | |
| // check_cpp and check_c99 check if the C++ or C99 functions are available. | |
| // | |
| // Then the call_* functions select an appropriate implementation. | |
| // | |
| // I used c99_func in a few places just to get a unique name. | |
| // | |
| // Important: when using 'using namespace' at namespace level, include as | |
| // little as possible in that namespace, as Visual C++ has an odd bug which | |
| // can cause the namespace to be imported at the global level. This seems to | |
| // happen mainly when there's a template in the same namesapce. | |
| #define BOOST_HASH_CALL_FLOAT_FUNC(cpp_func, c99_func, type1, type2) \ | |
| namespace boost_hash_detect_float_functions { \ | |
| template <class Float> \ | |
| boost::hash_detail::not_found c99_func(Float, type2); \ | |
| } \ | |
| \ | |
| namespace boost { \ | |
| namespace hash_detail { \ | |
| namespace c99_func##_detect { \ | |
| using namespace std; \ | |
| using namespace boost_hash_detect_float_functions; \ | |
| \ | |
| struct check { \ | |
| static type1 x; \ | |
| static type2 y; \ | |
| BOOST_STATIC_CONSTANT(bool, cpp = \ | |
| sizeof(float_type(cpp_func(x,y))) \ | |
| == sizeof(is<type1>)); \ | |
| BOOST_STATIC_CONSTANT(bool, c99 = \ | |
| sizeof(float_type(c99_func(x,y))) \ | |
| == sizeof(is<type1>)); \ | |
| }; \ | |
| } \ | |
| \ | |
| template <bool x> \ | |
| struct call_c99_##c99_func : \ | |
| boost::hash_detail::call_##cpp_func<double> {}; \ | |
| \ | |
| template <> \ | |
| struct call_c99_##c99_func<true> { \ | |
| typedef type1 float_type; \ | |
| \ | |
| template <typename T> \ | |
| inline type1 operator()(type1 a, T b) const \ | |
| { \ | |
| using namespace std; \ | |
| return c99_func(a, b); \ | |
| } \ | |
| }; \ | |
| \ | |
| template <bool x> \ | |
| struct call_cpp_##c99_func : \ | |
| call_c99_##c99_func< \ | |
| ::boost::hash_detail::c99_func##_detect::check::c99 \ | |
| > {}; \ | |
| \ | |
| template <> \ | |
| struct call_cpp_##c99_func<true> { \ | |
| typedef type1 float_type; \ | |
| \ | |
| template <typename T> \ | |
| inline type1 operator()(type1 a, T b) const \ | |
| { \ | |
| using namespace std; \ | |
| return cpp_func(a, b); \ | |
| } \ | |
| }; \ | |
| \ | |
| template <> \ | |
| struct call_##cpp_func<type1> : \ | |
| call_cpp_##c99_func< \ | |
| ::boost::hash_detail::c99_func##_detect::check::cpp \ | |
| > {}; \ | |
| } \ | |
| } | |
| #define BOOST_HASH_CALL_FLOAT_MACRO(cpp_func, c99_func, type1, type2) \ | |
| namespace boost { \ | |
| namespace hash_detail { \ | |
| \ | |
| template <> \ | |
| struct call_##cpp_func<type1> { \ | |
| typedef type1 float_type; \ | |
| inline type1 operator()(type1 x, type2 y) const { \ | |
| return c99_func(x, y); \ | |
| } \ | |
| }; \ | |
| } \ | |
| } | |
| #if defined(ldexpf) | |
| BOOST_HASH_CALL_FLOAT_MACRO(ldexp, ldexpf, float, int) | |
| #else | |
| BOOST_HASH_CALL_FLOAT_FUNC(ldexp, ldexpf, float, int) | |
| #endif | |
| #if defined(ldexpl) | |
| BOOST_HASH_CALL_FLOAT_MACRO(ldexp, ldexpl, long double, int) | |
| #else | |
| BOOST_HASH_CALL_FLOAT_FUNC(ldexp, ldexpl, long double, int) | |
| #endif | |
| #if defined(frexpf) | |
| BOOST_HASH_CALL_FLOAT_MACRO(frexp, frexpf, float, int*) | |
| #else | |
| BOOST_HASH_CALL_FLOAT_FUNC(frexp, frexpf, float, int*) | |
| #endif | |
| #if defined(frexpl) | |
| BOOST_HASH_CALL_FLOAT_MACRO(frexp, frexpl, long double, int*) | |
| #else | |
| BOOST_HASH_CALL_FLOAT_FUNC(frexp, frexpl, long double, int*) | |
| #endif | |
| #undef BOOST_HASH_CALL_FLOAT_MACRO | |
| #undef BOOST_HASH_CALL_FLOAT_FUNC | |
| namespace boost | |
| { | |
| namespace hash_detail | |
| { | |
| template <typename Float1, typename Float2> | |
| struct select_hash_type_impl { | |
| typedef double type; | |
| }; | |
| template <> | |
| struct select_hash_type_impl<float, float> { | |
| typedef float type; | |
| }; | |
| template <> | |
| struct select_hash_type_impl<long double, long double> { | |
| typedef long double type; | |
| }; | |
| // select_hash_type | |
| // | |
| // If there is support for a particular floating point type, use that | |
| // otherwise use double (there's always support for double). | |
| template <typename Float> | |
| struct select_hash_type : select_hash_type_impl< | |
| BOOST_DEDUCED_TYPENAME call_ldexp<Float>::float_type, | |
| BOOST_DEDUCED_TYPENAME call_frexp<Float>::float_type | |
| > {}; | |
| } | |
| } | |
| #endif |