--- /dev/null
+// functional_hash.h header -*- C++ -*-
+
+// Copyright (C) 2007, 2008, 2009, 2010 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 3, 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.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file bits/functional_hash.h
+ * This is an internal header file, included by other library headers.
+ * You should not attempt to use it directly.
+ */
+
+#ifndef _FUNCTIONAL_HASH_H
+#define _FUNCTIONAL_HASH_H 1
+
+#pragma GCC system_header
+
+#include <cstddef>
+#include <bits/stl_function.h>
+
+namespace std
+{
+ /** @defgroup hashes Hashes
+ * @ingroup functors
+ *
+ * Hashing functors taking a variable type and returning a @c std::size_t.
+ *
+ * @{
+ */
+
+ /// Primary class template hash.
+ template<typename _Tp>
+ struct hash : public std::unary_function<_Tp, size_t>
+ {
+ size_t
+ operator()(_Tp __val) const;
+ };
+
+ /// Partial specializations for pointer types.
+ template<typename _Tp>
+ struct hash<_Tp*> : public std::unary_function<_Tp*, size_t>
+ {
+ size_t
+ operator()(_Tp* __p) const
+ { return reinterpret_cast<size_t>(__p); }
+ };
+
+ // Explicit specializations for integer types.
+#define _Cxx_hashtable_define_trivial_hash(_Tp) \
+ template<> \
+ inline size_t \
+ hash<_Tp>::operator()(_Tp __val) const \
+ { return static_cast<size_t>(__val); }
+
+ /// Explicit specialization for bool.
+ _Cxx_hashtable_define_trivial_hash(bool);
+
+ /// Explicit specialization for char.
+ _Cxx_hashtable_define_trivial_hash(char);
+
+ /// Explicit specialization for signed char.
+ _Cxx_hashtable_define_trivial_hash(signed char);
+
+ /// Explicit specialization for unsigned char.
+ _Cxx_hashtable_define_trivial_hash(unsigned char);
+
+ /// Explicit specialization for wchar_t.
+ _Cxx_hashtable_define_trivial_hash(wchar_t);
+
+ /// Explicit specialization for char16_t.
+ _Cxx_hashtable_define_trivial_hash(char16_t);
+
+ /// Explicit specialization for char32_t.
+ _Cxx_hashtable_define_trivial_hash(char32_t);
+
+ /// Explicit specialization for short.
+ _Cxx_hashtable_define_trivial_hash(short);
+
+ /// Explicit specialization for int.
+ _Cxx_hashtable_define_trivial_hash(int);
+
+ /// Explicit specialization for long.
+ _Cxx_hashtable_define_trivial_hash(long);
+
+ /// Explicit specialization for long long.
+ _Cxx_hashtable_define_trivial_hash(long long);
+
+ /// Explicit specialization for unsigned short.
+ _Cxx_hashtable_define_trivial_hash(unsigned short);
+
+ /// Explicit specialization for unsigned int.
+ _Cxx_hashtable_define_trivial_hash(unsigned int);
+
+ /// Explicit specialization for unsigned long.
+ _Cxx_hashtable_define_trivial_hash(unsigned long);
+
+ /// Explicit specialization for unsigned long long.
+ _Cxx_hashtable_define_trivial_hash(unsigned long long);
+
+#undef _Cxx_hashtable_define_trivial_hash
+
+ // Fowler / Noll / Vo (FNV) Hash (type FNV-1a)
+
+ // Dummy generic implementation (for sizeof(size_t) != 4, 8).
+ template<size_t>
+ struct _Fnv_hash_base
+ {
+ template<typename _Tp>
+ static size_t
+ hash(const _Tp* __ptr, size_t __clength, size_t __hash = 0)
+ {
+ const char* __cptr = reinterpret_cast<const char*>(__ptr);
+ for (; __clength; --__clength)
+ __hash = (__hash * 131) + *__cptr++;
+ return __hash;
+ }
+ };
+
+ template<>
+ struct _Fnv_hash_base<4>
+ {
+ template<typename _Tp>
+ static size_t
+ hash(const _Tp* __ptr, size_t __clength,
+ size_t __hash = static_cast<size_t>(2166136261UL))
+ {
+ const char* __cptr = reinterpret_cast<const char*>(__ptr);
+ for (; __clength; --__clength)
+ {
+ __hash ^= static_cast<size_t>(*__cptr++);
+ __hash *= static_cast<size_t>(16777619UL);
+ }
+ return __hash;
+ }
+ };
+
+ template<>
+ struct _Fnv_hash_base<8>
+ {
+ template<typename _Tp>
+ static size_t
+ hash(const _Tp* __ptr, size_t __clength,
+ size_t __hash = static_cast<size_t>(14695981039346656037ULL))
+ {
+ const char* __cptr = reinterpret_cast<const char*>(__ptr);
+ for (; __clength; --__clength)
+ {
+ __hash ^= static_cast<size_t>(*__cptr++);
+ __hash *= static_cast<size_t>(1099511628211ULL);
+ }
+ return __hash;
+ }
+ };
+
+ struct _Fnv_hash
+ : public _Fnv_hash_base<sizeof(size_t)>
+ {
+ using _Fnv_hash_base<sizeof(size_t)>::hash;
+
+ template<typename _Tp>
+ static size_t
+ hash(const _Tp& __val)
+ { return hash(&__val, sizeof(__val)); }
+
+ template<typename _Tp>
+ static size_t
+ __hash_combine(const _Tp& __val, size_t __hash)
+ { return hash(&__val, sizeof(__val), __hash); }
+ };
+
+ /// Specialization for float.
+ template<>
+ inline size_t
+ hash<float>::operator()(float __val) const
+ {
+ // 0 and -0 both hash to zero.
+ return __val != 0.0f ? std::_Fnv_hash::hash(__val) : 0;
+ }
+
+ /// Specialization for double.
+ template<>
+ inline size_t
+ hash<double>::operator()(double __val) const
+ {
+ // 0 and -0 both hash to zero.
+ return __val != 0.0 ? std::_Fnv_hash::hash(__val) : 0;
+ }
+
+ /// Specialization for long double.
+ template<>
+ _GLIBCXX_PURE size_t
+ hash<long double>::operator()(long double __val) const;
+
+ // @} group hashes
+}
+
+#endif // _FUNCTIONAL_HASH_H
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