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// TR1 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 tr1/functional_hash.h

 *  This is an internal header file, included by other library headers.

 *  You should not attempt to use it directly.

 */

#ifndef _GLIBCXX_TR1_FUNCTIONAL_HASH_H

#define _GLIBCXX_TR1_FUNCTIONAL_HASH_H 1

#pragma GCC system_header

namespace std

{

namespace tr1

{

  /// Class template hash.

  // Declaration of default hash functor std::tr1::hash.  The types for

  // which std::tr1::hash<T> is well-defined is in clause 6.3.3. of the PDTR.

  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 _TR1_hashtable_define_trivial_hash(_Tp)         \

  template<>                                            \

    inline size_t                                       \

    hash<_Tp>::operator()(_Tp __val) const              \

    { return static_cast<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

  // 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<size_t>

    struct _Fnv_hash_base

    {

      template<typename _Tp>

        static size_t

        hash(const _Tp* __ptr, size_t __clength)

        {

          size_t __result = 0;

          const char* __cptr = reinterpret_cast<const char*>(__ptr);

          for (; __clength; --__clength)

            __result = (__result * 131) + *__cptr++;

          return __result;

        }

    };

  template<>

    struct _Fnv_hash_base<4>

    {

      template<typename _Tp>

        static size_t

        hash(const _Tp* __ptr, size_t __clength)

        {

          size_t __result = static_cast<size_t>(2166136261UL);

          const char* __cptr = reinterpret_cast<const char*>(__ptr);

          for (; __clength; --__clength)

            {

              __result ^= static_cast<size_t>(*__cptr++);

              __result *= static_cast<size_t>(16777619UL);

            }

          return __result;

        }

    };

  template<>

    struct _Fnv_hash_base<8>

    {

      template<typename _Tp>

        static size_t

        hash(const _Tp* __ptr, size_t __clength)

        {

          size_t __result

            = static_cast<size_t>(14695981039346656037ULL);

          const char* __cptr = reinterpret_cast<const char*>(__ptr);

          for (; __clength; --__clength)

            {

              __result ^= static_cast<size_t>(*__cptr++);

              __result *= static_cast<size_t>(1099511628211ULL);

            }

          return __result;

        }

    };

  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)); }

  };

  /// Explicit specializations for float.

  template<>

    inline size_t

    hash<float>::operator()(float __val) const

    {

      // 0 and -0 both hash to zero.

      return __val != 0.0f ? std::tr1::_Fnv_hash::hash(__val) : 0;

    }

  /// Explicit specializations for double.

  template<>

    inline size_t

    hash<double>::operator()(double __val) const

    {

      // 0 and -0 both hash to zero.

      return __val != 0.0 ? std::tr1::_Fnv_hash::hash(__val) : 0;

    }

  /// Explicit specializations for long double.

  template<>

    _GLIBCXX_PURE size_t

    hash<long double>::operator()(long double __val) const;

  /// Explicit specialization of member operator for non-builtin types.

  template<>

    _GLIBCXX_PURE size_t

    hash<string>::operator()(string) const;

  template<>

    _GLIBCXX_PURE size_t

    hash<const string&>::operator()(const string&) const;

#ifdef _GLIBCXX_USE_WCHAR_T

  template<>

    _GLIBCXX_PURE size_t

    hash<wstring>::operator()(wstring) const;

  template<>

    _GLIBCXX_PURE size_t

    hash<const wstring&>::operator()(const wstring&) const;

#endif

}

}

#endif // _GLIBCXX_TR1_FUNCTIONAL_HASH_H