+// TR1 functional -*- C++ -*-
+
+// Copyright (C) 2007 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.
+
+/** @file tr1/functional_hash.h
+ * This is an internal header file, included by other library headers.
+ * You should not attempt to use it directly.
+ */
+
+#ifndef _TR1_FUNCTIONAL_HASH_H
+#define _TR1_FUNCTIONAL_HASH_H 1
+
+#include <string>
+#include <cmath> // for std::frexp
+
+namespace std
+{
+_GLIBCXX_BEGIN_NAMESPACE(tr1)
+
+ // Definition of default hash function std::tr1::hash<>. The types for
+ // which std::tr1::hash<T> is defined is in clause 6.3.3. of the PDTR.
+ template<typename T>
+ struct hash;
+
+#define _TR1_hashtable_define_trivial_hash(_Tp) \
+ template<> \
+ struct hash<_Tp> \
+ : public std::unary_function<_Tp, std::size_t> \
+ { \
+ std::size_t \
+ operator()(_Tp __val) const \
+ { return static_cast<std::size_t>(__val); } \
+ }
+
+ _TR1_hashtable_define_trivial_hash(bool);
+ _TR1_hashtable_define_trivial_hash(char);
+ _TR1_hashtable_define_trivial_hash(signed char);
+ _TR1_hashtable_define_trivial_hash(unsigned char);
+ _TR1_hashtable_define_trivial_hash(wchar_t);
+ _TR1_hashtable_define_trivial_hash(short);
+ _TR1_hashtable_define_trivial_hash(int);
+ _TR1_hashtable_define_trivial_hash(long);
+ _TR1_hashtable_define_trivial_hash(long long);
+ _TR1_hashtable_define_trivial_hash(unsigned short);
+ _TR1_hashtable_define_trivial_hash(unsigned int);
+ _TR1_hashtable_define_trivial_hash(unsigned long);
+ _TR1_hashtable_define_trivial_hash(unsigned long long);
+
+#undef _TR1_hashtable_define_trivial_hash
+
+ template<typename _Tp>
+ struct hash<_Tp*>
+ : public std::unary_function<_Tp*, std::size_t>
+ {
+ std::size_t
+ operator()(_Tp* __p) const
+ { return reinterpret_cast<std::size_t>(__p); }
+ };
+
+ // Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
+ // (used by the next specializations of std::tr1::hash<>)
+
+ // Dummy generic implementation (for sizeof(size_t) != 4, 8).
+ template<std::size_t = sizeof(std::size_t)>
+ struct _Fnv_hash
+ {
+ static std::size_t
+ hash(const char* __first, std::size_t __length)
+ {
+ std::size_t __result = 0;
+ for (; __length > 0; --__length)
+ __result = (__result * 131) + *__first++;
+ return __result;
+ }
+ };
+
+ template<>
+ struct _Fnv_hash<4>
+ {
+ static std::size_t
+ hash(const char* __first, std::size_t __length)
+ {
+ std::size_t __result = static_cast<std::size_t>(2166136261UL);
+ for (; __length > 0; --__length)
+ {
+ __result ^= static_cast<std::size_t>(*__first++);
+ __result *= static_cast<std::size_t>(16777619UL);
+ }
+ return __result;
+ }
+ };
+
+ template<>
+ struct _Fnv_hash<8>
+ {
+ static std::size_t
+ hash(const char* __first, std::size_t __length)
+ {
+ std::size_t __result =
+ static_cast<std::size_t>(14695981039346656037ULL);
+ for (; __length > 0; --__length)
+ {
+ __result ^= static_cast<std::size_t>(*__first++);
+ __result *= static_cast<std::size_t>(1099511628211ULL);
+ }
+ return __result;
+ }
+ };
+
+ // XXX String and floating point hashes probably shouldn't be inline
+ // member functions, since are nontrivial. Once we have the framework
+ // for TR1 .cc files, these should go in one.
+ template<>
+ struct hash<std::string>
+ : public std::unary_function<std::string, std::size_t>
+ {
+ std::size_t
+ operator()(const std::string& __s) const
+ { return _Fnv_hash<>::hash(__s.data(), __s.length()); }
+ };
+
+#ifdef _GLIBCXX_USE_WCHAR_T
+ template<>
+ struct hash<std::wstring>
+ : public std::unary_function<std::wstring, std::size_t>
+ {
+ std::size_t
+ operator()(const std::wstring& __s) const
+ {
+ return _Fnv_hash<>::hash(reinterpret_cast<const char*>(__s.data()),
+ __s.length() * sizeof(wchar_t));
+ }
+ };
+#endif
+
+ template<>
+ struct hash<float>
+ : public std::unary_function<float, std::size_t>
+ {
+ std::size_t
+ operator()(float __fval) const
+ {
+ std::size_t __result = 0;
+
+ // 0 and -0 both hash to zero.
+ if (__fval != 0.0f)
+ __result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__fval),
+ sizeof(__fval));
+ return __result;
+ }
+ };
+
+ template<>
+ struct hash<double>
+ : public std::unary_function<double, std::size_t>
+ {
+ std::size_t
+ operator()(double __dval) const
+ {
+ std::size_t __result = 0;
+
+ // 0 and -0 both hash to zero.
+ if (__dval != 0.0)
+ __result = _Fnv_hash<>::hash(reinterpret_cast<const char*>(&__dval),
+ sizeof(__dval));
+ return __result;
+ }
+ };
+
+ // For long double, careful with random padding bits (e.g., on x86,
+ // 10 bytes -> 12 bytes) and resort to frexp.
+ template<>
+ struct hash<long double>
+ : public std::unary_function<long double, std::size_t>
+ {
+ std::size_t
+ operator()(long double __ldval) const
+ {
+ std::size_t __result = 0;
+
+ int __exponent;
+ __ldval = std::frexp(__ldval, &__exponent);
+ __ldval = __ldval < 0.0l ? -(__ldval + 0.5l) : __ldval;
+
+ const long double __mult =
+ std::numeric_limits<std::size_t>::max() + 1.0l;
+ __ldval *= __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 std::size_t __hibits = (std::size_t)__ldval;
+ __ldval = (__ldval - (long double)__hibits) * __mult;
+
+ const std::size_t __coeff =
+ (std::numeric_limits<std::size_t>::max()
+ / std::numeric_limits<long double>::max_exponent);
+
+ __result = __hibits + (std::size_t)__ldval + __coeff * __exponent;
+
+ return __result;
+ }
+ };
+
+_GLIBCXX_END_NAMESPACE
+}
+
+#endif
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