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PR libstdc++/28080 (partial)
2007-03-03 Paolo Carlini <pcarlini@suse.de> PR libstdc++/28080 (partial) * include/tr1/functional: Split out hash bits to... * include/tr1/functional_hash.h: ...here. * include/Makefile.am: Add. * include/tr1/unordered_set: Include the latter instead. * include/tr1/unordered_map: Likewise. * include/Makefile.in: Regenerate. * include/tr1/utility (get(std::pair<>&), get(const std::pair<>&)): Mark inline. From-SVN: r122519
This commit is contained in:
Paolo Carlini
232
libstdc++-v3/include/tr1/functional_hash.h
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232
libstdc++-v3/include/tr1/functional_hash.h
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// TR1 functional -*- C++ -*-
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// Copyright (C) 2007 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 2, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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/** @file tr1/functional_hash.h
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* This is an internal header file, included by other library headers.
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* You should not attempt to use it directly.
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*/
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#ifndef _TR1_FUNCTIONAL_HASH_H
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#define _TR1_FUNCTIONAL_HASH_H 1
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#include <string>
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#include <cmath> // for std::frexp
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namespace std
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{
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_GLIBCXX_BEGIN_NAMESPACE(tr1)
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// Definition of default hash function std::tr1::hash<>. The types for
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// which std::tr1::hash<T> is defined is in clause 6.3.3. of the PDTR.
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template<typename T>
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struct hash;
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#define _TR1_hashtable_define_trivial_hash(_Tp) \
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template<> \
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struct hash<_Tp> \
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: public std::unary_function<_Tp, std::size_t> \
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{ \
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std::size_t \
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operator()(_Tp __val) const \
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{ return static_cast<std::size_t>(__val); } \
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}
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_TR1_hashtable_define_trivial_hash(bool);
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_TR1_hashtable_define_trivial_hash(char);
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_TR1_hashtable_define_trivial_hash(signed char);
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_TR1_hashtable_define_trivial_hash(unsigned char);
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_TR1_hashtable_define_trivial_hash(wchar_t);
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_TR1_hashtable_define_trivial_hash(short);
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_TR1_hashtable_define_trivial_hash(int);
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_TR1_hashtable_define_trivial_hash(long);
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_TR1_hashtable_define_trivial_hash(long long);
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_TR1_hashtable_define_trivial_hash(unsigned short);
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_TR1_hashtable_define_trivial_hash(unsigned int);
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_TR1_hashtable_define_trivial_hash(unsigned long);
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_TR1_hashtable_define_trivial_hash(unsigned long long);
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#undef _TR1_hashtable_define_trivial_hash
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template<typename _Tp>
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struct hash<_Tp*>
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: public std::unary_function<_Tp*, std::size_t>
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{
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std::size_t
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operator()(_Tp* __p) const
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{ return reinterpret_cast<std::size_t>(__p); }
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};
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// Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
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// (used by the next specializations of std::tr1::hash<>)
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// Dummy generic implementation (for sizeof(size_t) != 4, 8).
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template<std::size_t = sizeof(std::size_t)>
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struct _Fnv_hash
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{
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static std::size_t
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hash(const char* __first, std::size_t __length)
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{
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std::size_t __result = 0;
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for (; __length > 0; --__length)
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__result = (__result * 131) + *__first++;
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return __result;
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}
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};
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template<>
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struct _Fnv_hash<4>
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{
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static std::size_t
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hash(const char* __first, std::size_t __length)
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{
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std::size_t __result = static_cast<std::size_t>(2166136261UL);
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for (; __length > 0; --__length)
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{
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__result ^= static_cast<std::size_t>(*__first++);
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__result *= static_cast<std::size_t>(16777619UL);
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}
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return __result;
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}
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};
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template<>
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struct _Fnv_hash<8>
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{
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static std::size_t
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hash(const char* __first, std::size_t __length)
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{
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std::size_t __result =
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static_cast<std::size_t>(14695981039346656037ULL);
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for (; __length > 0; --__length)
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{
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__result ^= static_cast<std::size_t>(*__first++);
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__result *= static_cast<std::size_t>(1099511628211ULL);
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}
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return __result;
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}
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};
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// XXX String and floating point hashes probably shouldn't be inline
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// member functions, since are nontrivial. Once we have the framework
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// for TR1 .cc files, these should go in one.
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template<>
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struct hash<std::string>
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: public std::unary_function<std::string, std::size_t>
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{
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std::size_t
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operator()(const std::string& __s) const
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{ return _Fnv_hash<>::hash(__s.data(), __s.length()); }
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};
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#ifdef _GLIBCXX_USE_WCHAR_T
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template<>
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struct hash<std::wstring>
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: public std::unary_function<std::wstring, std::size_t>
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{
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std::size_t
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operator()(const std::wstring& __s) const
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{
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return _Fnv_hash<>::hash(reinterpret_cast<const char*>(__s.data()),
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__s.length() * sizeof(wchar_t));
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}
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};
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#endif
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template<>
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struct hash<float>
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: public std::unary_function<float, std::size_t>
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{
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std::size_t
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operator()(float __fval) const
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{
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std::size_t __result = 0;
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// 0 and -0 both hash to zero.
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if (__fval != 0.0f)
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__result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__fval),
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sizeof(__fval));
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return __result;
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}
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};
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template<>
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struct hash<double>
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: public std::unary_function<double, std::size_t>
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{
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std::size_t
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operator()(double __dval) const
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{
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std::size_t __result = 0;
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// 0 and -0 both hash to zero.
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if (__dval != 0.0)
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__result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__dval),
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sizeof(__dval));
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return __result;
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}
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};
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// For long double, careful with random padding bits (e.g., on x86,
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// 10 bytes -> 12 bytes) and resort to frexp.
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template<>
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struct hash<long double>
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: public std::unary_function<long double, std::size_t>
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{
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std::size_t
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operator()(long double __ldval) const
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{
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std::size_t __result = 0;
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int __exponent;
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__ldval = std::frexp(__ldval, &__exponent);
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__ldval = __ldval < 0.0l ? -(__ldval + 0.5l) : __ldval;
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const long double __mult =
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std::numeric_limits<std::size_t>::max() + 1.0l;
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__ldval *= __mult;
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// Try to use all the bits of the mantissa (really necessary only
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// on 32-bit targets, at least for 80-bit floating point formats).
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const std::size_t __hibits = (std::size_t)__ldval;
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__ldval = (__ldval - (long double)__hibits) * __mult;
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const std::size_t __coeff =
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(std::numeric_limits<std::size_t>::max()
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/ std::numeric_limits<long double>::max_exponent);
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__result = __hibits + (std::size_t)__ldval + __coeff * __exponent;
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return __result;
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}
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};
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_GLIBCXX_END_NAMESPACE
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}
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#endif
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