forked from boostorg/functional
Daniel James
1c701a70bb
in hash and seperate out some of the detail headers. Merged revisions 53159-53161,53167-53169,53175,53185,53205,53247-53248,53254 via svnmerge from https://svn.boost.org/svn/boost/trunk ........ r53159 | danieljames | 2009-05-21 22:21:11 +0100 (Thu, 21 May 2009) | 1 line Move the hash limits workaround into its own file. ........ r53160 | danieljames | 2009-05-21 22:21:44 +0100 (Thu, 21 May 2009) | 1 line Move the two different hash float implementation into their own header. ........ r53161 | danieljames | 2009-05-21 22:22:04 +0100 (Thu, 21 May 2009) | 1 line Try to automatically detect which float functions are available. ........ r53167 | danieljames | 2009-05-22 07:00:56 +0100 (Fri, 22 May 2009) | 1 line Fix a typo. ........ r53168 | danieljames | 2009-05-22 07:01:19 +0100 (Fri, 22 May 2009) | 3 lines Spell out exactly which functions can be used with which types. I was hitting some ambiguity errors when the function was for the wrong type. ........ r53169 | danieljames | 2009-05-22 07:01:35 +0100 (Fri, 22 May 2009) | 1 line Some STLport fixes for hash. ........ r53175 | danieljames | 2009-05-22 14:35:56 +0100 (Fri, 22 May 2009) | 2 lines Rename struct to avoid using 'type::'type' which confuses some compilers. ........ r53185 | danieljames | 2009-05-22 20:00:35 +0100 (Fri, 22 May 2009) | 1 line Explicitly qualify 'none' to avoid confusion with boost::none. ........ r53205 | danieljames | 2009-05-23 16:21:38 +0100 (Sat, 23 May 2009) | 4 lines Try to deal with macros for frexpl and ldexpl. The error message for msvc-9.0~wm5~stlport5.2 suggests that frexpl and ldexpl are macros. ........ r53247 | danieljames | 2009-05-25 14:45:16 +0100 (Mon, 25 May 2009) | 4 lines Check for float functions with less templates. The only template mechanism now used is full specialization, so this should hopefully be more portable to compilers we don't test. ........ r53248 | danieljames | 2009-05-25 15:27:00 +0100 (Mon, 25 May 2009) | 1 line Fix a couple of clumsy errors in the last commit. ........ r53254 | danieljames | 2009-05-25 20:44:52 +0100 (Mon, 25 May 2009) | 1 line Hash change log. ........ [SVN r53361]
239 lines
10 KiB
C++
239 lines
10 KiB
C++
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// Copyright 2005-2009 Daniel James.
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#if !defined(BOOST_FUNCTIONAL_HASH_DETAIL_FLOAT_FUNCTIONS_HPP)
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#define BOOST_FUNCTIONAL_HASH_DETAIL_FLOAT_FUNCTIONS_HPP
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#include <boost/config.hpp>
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#include <boost/config/no_tr1/cmath.hpp>
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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# pragma once
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#endif
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// The C++ standard requires that the C float functions are overloarded
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// for float, double and long double in the std namespace, but some of the older
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// library implementations don't support this. On some that don't, the C99
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// float functions (frexpf, frexpl, etc.) are available.
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//
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// The following tries to automatically detect which are available.
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namespace boost {
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namespace hash_detail {
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// Returned by dummy versions of the float functions.
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struct not_found {
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// Implicitly convertible to float and long double in order to avoid
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// a compile error when the dummy float functions are used.
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inline operator float() const { return 0; }
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inline operator long double() const { return 0; }
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};
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// A type for detecting the return type of functions.
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template <typename T> struct is;
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template <> struct is<float> { char x[10]; };
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template <> struct is<double> { char x[20]; };
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template <> struct is<long double> { char x[30]; };
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template <> struct is<boost::hash_detail::not_found> { char x[40]; };
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// Used to convert the return type of a function to a type for sizeof.
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template <typename T> is<T> float_type(T);
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// call_ldexp
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//
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// This will get specialized for float and long double
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template <typename Float> struct call_ldexp
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{
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typedef double float_type;
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inline double operator()(double a, int b) const
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{
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using namespace std;
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return ldexp(a, b);
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}
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};
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// call_frexp
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//
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// This will get specialized for float and long double
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template <typename Float> struct call_frexp
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{
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typedef double float_type;
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inline double operator()(double a, int* b) const
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{
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using namespace std;
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return frexp(a, b);
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}
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};
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}
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}
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// A namespace for dummy functions to detect when the actual function we want
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// isn't available. ldexpl, ldexpf etc. might be added tby the macros below.
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//
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// AFAICT these have to be outside of the boost namespace, as if they're in
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// the boost namespace they'll always be preferable to any other function
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// (since the arguments are built in types, ADL can't be used).
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namespace BOOST_HASH_DETECT_FLOAT_FUNCTIONS {
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template <class Float> boost::hash_detail::not_found ldexp(Float, int);
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template <class Float> boost::hash_detail::not_found frexp(Float, int*);
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}
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// Macros for generating specializations of call_ldexp and call_frexp.
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//
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// check_cpp and check_c99 check if the C++ or C99 functions are available.
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//
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// Then the call_* functions select an appropriate implementation.
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//
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// I used c99_func in a few places just to get a unique name.
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#define BOOST_HASH_CALL_FLOAT_FUNC(cpp_func, c99_func, type1, type2) \
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namespace BOOST_HASH_DETECT_FLOAT_FUNCTIONS { \
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boost::hash_detail::not_found c99_func(int, type2); \
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} \
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\
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namespace boost { \
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namespace hash_detail { \
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namespace c99_func##_detect { \
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using namespace std; \
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using namespace BOOST_HASH_DETECT_FLOAT_FUNCTIONS; \
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\
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struct check { \
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static type1 x; \
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static type2 y; \
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BOOST_STATIC_CONSTANT(bool, cpp = \
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sizeof(float_type(cpp_func(x,y))) \
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== sizeof(is<type1>)); \
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BOOST_STATIC_CONSTANT(bool, c99 = \
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sizeof(float_type(c99_func(x,y))) \
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== sizeof(is<type1>)); \
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}; \
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\
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template <bool x> \
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struct call_c99 : \
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boost::hash_detail::call_##cpp_func<double> {}; \
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\
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template <> \
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struct call_c99<true> { \
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typedef type1 float_type; \
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\
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template <typename T> \
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inline type1 operator()(type1 a, T b) const \
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{ \
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return c99_func(a, b); \
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} \
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}; \
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\
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template <bool x> \
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struct call_cpp : \
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call_c99< \
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::boost::hash_detail::c99_func##_detect::check::c99 \
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> {}; \
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\
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template <> \
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struct call_cpp<true> { \
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typedef type1 float_type; \
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\
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template <typename T> \
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inline type1 operator()(type1 a, T b) const \
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{ \
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return cpp_func(a, b); \
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} \
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}; \
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} \
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\
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template <> \
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struct call_##cpp_func<type1> : \
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c99_func##_detect::call_cpp< \
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::boost::hash_detail::c99_func##_detect::check::cpp \
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> {}; \
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} \
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}
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#define BOOST_HASH_CALL_FLOAT_MACRO(cpp_func, c99_func, type1, type2) \
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namespace boost { \
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namespace hash_detail { \
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\
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template <> \
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struct call_##cpp_func<type1> { \
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typedef type1 float_type; \
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inline type1 operator()(type1 x, type2 y) const { \
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return c99_func(x, y); \
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} \
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}; \
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} \
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}
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#if defined(ldexpf)
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BOOST_HASH_CALL_FLOAT_MACRO(ldexp, ldexpf, float, int)
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#else
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BOOST_HASH_CALL_FLOAT_FUNC(ldexp, ldexpf, float, int)
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#endif
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#if defined(ldexpl)
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BOOST_HASH_CALL_FLOAT_MACRO(ldexp, ldexpl, long double, int)
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#else
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BOOST_HASH_CALL_FLOAT_FUNC(ldexp, ldexpl, long double, int)
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#endif
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#if defined(frexpf)
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BOOST_HASH_CALL_FLOAT_MACRO(frexp, frexpf, float, int*)
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#else
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BOOST_HASH_CALL_FLOAT_FUNC(frexp, frexpf, float, int*)
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#endif
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#if defined(frexpl)
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BOOST_HASH_CALL_FLOAT_MACRO(frexp, frexpl, long double, int*)
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#else
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BOOST_HASH_CALL_FLOAT_FUNC(frexp, frexpl, long double, int*)
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#endif
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#undef BOOST_HASH_CALL_FLOAT_MACRO
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#undef BOOST_HASH_CALL_FLOAT_FUNC
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namespace boost
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{
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namespace hash_detail
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{
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template <typename Float1, typename Float2>
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struct select_hash_type_impl {
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typedef double type;
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};
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template <>
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struct select_hash_type_impl<float, float> {
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typedef float type;
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};
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template <>
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struct select_hash_type_impl<long double, long double> {
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typedef long double type;
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};
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// select_hash_type
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//
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// If there is support for a particular floating point type, use that
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// otherwise use double (there's always support for double).
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template <typename Float>
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struct select_hash_type : select_hash_type_impl<
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BOOST_DEDUCED_TYPENAME call_ldexp<Float>::float_type,
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BOOST_DEDUCED_TYPENAME call_frexp<Float>::float_type
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> {};
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}
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}
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#endif
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