189 lines
5.5 KiB
C++
189 lines
5.5 KiB
C++
// TR1 functional -*- C++ -*-
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// Copyright (C) 2007, 2008 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_impl/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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namespace std
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{
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_GLIBCXX_BEGIN_NAMESPACE_TR1
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/// Class template hash.
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// Declaration of default hash functor std::tr1::hash. The types for
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// which std::tr1::hash<T> is well-defined is in clause 6.3.3. of the PDTR.
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template<typename _Tp>
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struct hash : public std::unary_function<_Tp, size_t>
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{
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size_t
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operator()(_Tp __val) const;
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};
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/// Partial specializations for pointer types.
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template<typename _Tp>
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struct hash<_Tp*> : public std::unary_function<_Tp*, size_t>
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{
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size_t
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operator()(_Tp* __p) const
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{ return reinterpret_cast<size_t>(__p); }
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};
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/// Explicit specializations for integer types.
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#define _TR1_hashtable_define_trivial_hash(_Tp) \
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template<> \
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inline size_t \
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hash<_Tp>::operator()(_Tp __val) const \
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{ return static_cast<size_t>(__val); }
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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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#ifdef _GLIBCXX_INCLUDE_AS_CXX0X
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_TR1_hashtable_define_trivial_hash(char16_t);
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_TR1_hashtable_define_trivial_hash(char32_t);
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#endif
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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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// 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<size_t = sizeof(size_t)>
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struct _Fnv_hash
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{
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static size_t
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hash(const char* __first, size_t __length)
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{
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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 size_t
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hash(const char* __first, size_t __length)
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{
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size_t __result = static_cast<size_t>(2166136261UL);
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for (; __length > 0; --__length)
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{
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__result ^= static_cast<size_t>(*__first++);
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__result *= static_cast<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 size_t
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hash(const char* __first, size_t __length)
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{
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size_t __result =
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static_cast<size_t>(14695981039346656037ULL);
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for (; __length > 0; --__length)
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{
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__result ^= static_cast<size_t>(*__first++);
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__result *= static_cast<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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/// Explicit specializations for float.
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template<>
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inline size_t
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hash<float>::operator()(float __val) const
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{
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size_t __result = 0;
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// 0 and -0 both hash to zero.
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if (__val != 0.0f)
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__result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__val),
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sizeof(__val));
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return __result;
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};
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/// Explicit specializations for double.
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template<>
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inline size_t
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hash<double>::operator()(double __val) const
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{
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size_t __result = 0;
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// 0 and -0 both hash to zero.
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if (__val != 0.0)
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__result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__val),
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sizeof(__val));
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return __result;
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};
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/// Explicit specializations for long double.
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template<>
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size_t
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hash<long double>::operator()(long double __val) const;
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/// Explicit specialization of member operator for non-builtin types.
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template<>
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size_t
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hash<string>::operator()(string) const;
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template<>
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size_t
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hash<const string&>::operator()(const string&) const;
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#ifdef _GLIBCXX_USE_WCHAR_T
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template<>
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size_t
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hash<wstring>::operator()(wstring) const;
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template<>
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size_t
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hash<const wstring&>::operator()(const wstring&) const;
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#endif
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_GLIBCXX_END_NAMESPACE_TR1
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}
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