| // std::hash and std::tr1::hash definitions -*- C++ -*- |
| |
| // Copyright (C) 2007, 2008 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library is free |
| // software; you can redistribute it and/or modify it under the |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 2, or (at your option) |
| // any later version. |
| |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // You should have received a copy of the GNU General Public License |
| // along with this library; see the file COPYING. If not, write to |
| // the Free Software Foundation, 51 Franklin Street, Fifth Floor, |
| // Boston, MA 02110-1301, USA. |
| |
| // As a special exception, you may use this file as part of a free software |
| // library without restriction. Specifically, if other files instantiate |
| // templates or use macros or inline functions from this file, or you compile |
| // this file and link it with other files to produce an executable, this |
| // file does not by itself cause the resulting executable to be covered by |
| // the GNU General Public License. This exception does not however |
| // invalidate any other reasons why the executable file might be covered by |
| // the GNU General Public License. |
| |
| #include <cstddef> |
| #include <string> |
| #include <cmath> |
| |
| #ifdef __GXX_EXPERIMENTAL_CXX0X__ |
| #include <functional> |
| # define _GLIBCXX_BEGIN_NAMESPACE_TR1 |
| # define _GLIBCXX_END_NAMESPACE_TR1 |
| #else |
| #include <tr1/functional> |
| # define _GLIBCXX_BEGIN_NAMESPACE_TR1 namespace tr1 { |
| # define _GLIBCXX_END_NAMESPACE_TR1 } |
| #endif |
| |
| namespace std |
| { |
| _GLIBCXX_BEGIN_NAMESPACE_TR1 |
| |
| // For long double, careful with random padding bits (e.g., on x86, |
| // 10 bytes -> 12 bytes) and resort to frexp. |
| template<> |
| size_t |
| hash<long double>::operator()(long double __val) const |
| { |
| size_t __result = 0; |
| |
| int __exponent; |
| __val = std::frexp(__val, &__exponent); |
| __val = __val < 0.0l ? -(__val + 0.5l) : __val; |
| |
| const long double __mult = |
| __gnu_cxx::__numeric_traits<size_t>::__max + 1.0l; |
| __val *= __mult; |
| |
| // Try to use all the bits of the mantissa (really necessary only |
| // on 32-bit targets, at least for 80-bit floating point formats). |
| const size_t __hibits = (size_t)__val; |
| __val = (__val - (long double)__hibits) * __mult; |
| |
| const size_t __coeff = |
| __gnu_cxx::__numeric_traits<size_t>::__max / __LDBL_MAX_EXP__; |
| |
| __result = __hibits + (size_t)__val + __coeff * __exponent; |
| |
| return __result; |
| }; |
| |
| #ifndef _GLIBCXX_LONG_DOUBLE_COMPAT_IMPL |
| template<> |
| size_t |
| hash<string>::operator()(string __s) const |
| { return _Fnv_hash<>::hash(__s.data(), __s.length()); } |
| |
| template<> |
| size_t |
| hash<const string&>::operator()(const string& __s) const |
| { return _Fnv_hash<>::hash(__s.data(), __s.length()); } |
| |
| #ifdef _GLIBCXX_USE_WCHAR_T |
| template<> |
| size_t |
| hash<wstring>::operator()(wstring __s) const |
| { |
| const char* __p = reinterpret_cast<const char*>(__s.data()); |
| return _Fnv_hash<>::hash(__p, __s.length() * sizeof(wchar_t)); |
| } |
| |
| template<> |
| size_t |
| hash<const wstring&>::operator()(const wstring& __s) const |
| { |
| const char* __p = reinterpret_cast<const char*>(__s.data()); |
| return _Fnv_hash<>::hash(__p, __s.length() * sizeof(wchar_t)); |
| } |
| #endif |
| #endif |
| |
| _GLIBCXX_END_NAMESPACE_TR1 |
| } |