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/usr/include/c++/8/bits/functional_hash.h

// functional_hash.h header -*- C++ -*-

// Copyright (C) 2007-2018 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.
 *  Do not attempt to use it directly. @headername{functional}
 */

#ifndef _FUNCTIONAL_HASH_H
#define _FUNCTIONAL_HASH_H 1

#pragma GCC system_header

#include <bits/hash_bytes.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /** @defgroup hashes Hashes
   *  @ingroup functors
   *
   *   Hashing functors taking a variable type and returning a @c std::size_t.
   *
   *  @{
   */

  template<typename _Result, typename _Arg>
    struct __hash_base
    {
      typedef _Result     result_type _GLIBCXX17_DEPRECATED;
      typedef _Arg      argument_type _GLIBCXX17_DEPRECATED;
    };

  /// Primary class template hash.
  template<typename _Tp>
    struct hash;

  template<typename _Tp, typename = void>
    struct __poison_hash
    {
      static constexpr bool __enable_hash_call = false;
    private:
      // Private rather than deleted to be non-trivially-copyable.
      __poison_hash(__poison_hash&&);
      ~__poison_hash();
    };

  template<typename _Tp>
    struct __poison_hash<_Tp, __void_t<decltype(hash<_Tp>()(declval<_Tp>()))>>
    {
      static constexpr bool __enable_hash_call = true;
    };

  // Helper struct for SFINAE-poisoning non-enum types.
  template<typename _Tp, bool = is_enum<_Tp>::value>
    struct __hash_enum
    {
    private:
      // Private rather than deleted to be non-trivially-copyable.
      __hash_enum(__hash_enum&&);
      ~__hash_enum();
    };

  // Helper struct for hash with enum types.
  template<typename _Tp>
    struct __hash_enum<_Tp, true> : public __hash_base<size_t, _Tp>
    {
      size_t
      operator()(_Tp __val) const noexcept
      {
       using __type = typename underlying_type<_Tp>::type;
       return hash<__type>{}(static_cast<__type>(__val));
      }
    };

  /// Primary class template hash, usable for enum types only.
  // Use with non-enum types still SFINAES.
  template<typename _Tp>
    struct hash : __hash_enum<_Tp>
    { };

  /// Partial specializations for pointer types.
  template<typename _Tp>
    struct hash<_Tp*> : public __hash_base<size_t, _Tp*>
    {
      size_t
      operator()(_Tp* __p) const noexcept
      { return reinterpret_cast<size_t>(__p); }
    };

  // Explicit specializations for integer types.
#define _Cxx_hashtable_define_trivial_hash(_Tp) 	\
  template<>						\
    struct hash<_Tp> : public __hash_base<size_t, _Tp>  \
    {                                                   \
      size_t                                            \
      operator()(_Tp __val) const noexcept              \
      { 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)

#ifdef __GLIBCXX_TYPE_INT_N_0
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_0)
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_0 unsigned)
#endif
#ifdef __GLIBCXX_TYPE_INT_N_1
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_1)
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_1 unsigned)
#endif
#ifdef __GLIBCXX_TYPE_INT_N_2
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_2)
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_2 unsigned)
#endif
#ifdef __GLIBCXX_TYPE_INT_N_3
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_3)
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_3 unsigned)
#endif

#undef _Cxx_hashtable_define_trivial_hash

  struct _Hash_impl
  {
    static size_t
    hash(const void* __ptr, size_t __clength,
	 size_t __seed = static_cast<size_t>(0xc70f6907UL))
    { return _Hash_bytes(__ptr, __clength, __seed); }

    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); }
  };

  // A hash function similar to FNV-1a (see PR59406 for how it differs).
  struct _Fnv_hash_impl
  {
    static size_t
    hash(const void* __ptr, size_t __clength,
	 size_t __seed = static_cast<size_t>(2166136261UL))
    { return _Fnv_hash_bytes(__ptr, __clength, __seed); }

    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<>
    struct hash<float> : public __hash_base<size_t, float>
    {
      size_t
      operator()(float __val) const noexcept
      {
	// 0 and -0 both hash to zero.
	return __val != 0.0f ? std::_Hash_impl::hash(__val) : 0;
      }
    };

  /// Specialization for double.
  template<>
    struct hash<double> : public __hash_base<size_t, double>
    {
      size_t
      operator()(double __val) const noexcept
      {
	// 0 and -0 both hash to zero.
	return __val != 0.0 ? std::_Hash_impl::hash(__val) : 0;
      }
    };

  /// Specialization for long double.
  template<>
    struct hash<long double>
    : public __hash_base<size_t, long double>
    {
      _GLIBCXX_PURE size_t
      operator()(long double __val) const noexcept;
    };

  // @} group hashes

  // Hint about performance of hash functor. If not fast the hash-based
  // containers will cache the hash code.
  // Default behavior is to consider that hashers are fast unless specified
  // otherwise.
  template<typename _Hash>
    struct __is_fast_hash : public std::true_type
    { };

  template<>
    struct __is_fast_hash<hash<long double>> : public std::false_type
    { };

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif // _FUNCTIONAL_HASH_H

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algorithmfwd.h	21.23 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
allocated_ptr.h	3.22 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
allocator.h	7.39 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
alloc_traits.h	19.60 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
atomic_base.h	23.28 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
atomic_futex.h	9.35 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
atomic_lockfree_defines.h	2.20 KB	lrw-r--r--	2025-08-26 09:45:07	Edit Download recursive recursive
basic_ios.h	15.70 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
basic_ios.tcc	5.94 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
basic_string.h	237.01 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
basic_string.tcc	52.50 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
boost_concept_check.h	26.52 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
c++0x_warning.h	1.44 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
char_traits.h	20.42 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
codecvt.h	20.79 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
concept_check.h	3.34 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
cpp_type_traits.h	9.56 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
cxxabi_forced.h	1.77 KB	lrw-r--r--	2025-08-26 09:45:07	Edit Download recursive recursive
cxxabi_init_exception.h	2.17 KB	lrw-r--r--	2025-08-26 09:45:07	Edit Download recursive recursive
deque.tcc	33.32 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
enable_special_members.h	12.10 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
exception.h	2.23 KB	lrw-r--r--	2025-08-26 09:45:07	Edit Download recursive recursive
exception_defines.h	1.61 KB	lrw-r--r--	2025-08-26 09:45:07	Edit Download recursive recursive
exception_ptr.h	5.84 KB	lrw-r--r--	2025-08-26 09:45:07	Edit Download recursive recursive
forward_list.h	47.77 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
forward_list.tcc	12.86 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
fstream.tcc	32.03 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
fs_dir.h	14.38 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
fs_fwd.h	10.04 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
fs_ops.h	9.50 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
fs_path.h	32.12 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
functexcept.h	3.18 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
functional_hash.h	8.04 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
gslice.h	5.39 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
gslice_array.h	7.59 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
hashtable.h	72.06 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
hashtable_policy.h	66.38 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
hash_bytes.h	2.10 KB	lrw-r--r--	2025-08-26 09:45:07	Edit Download recursive recursive
indirect_array.h	7.68 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
invoke.h	3.57 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
ios_base.h	30.30 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
istream.tcc	30.36 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
list.tcc	15.60 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
localefwd.h	5.51 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
locale_classes.h	24.31 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
locale_classes.tcc	8.18 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
locale_conv.h	15.72 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
locale_facets.h	90.16 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
locale_facets.tcc	38.62 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
locale_facets_nonio.h	67.36 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
locale_facets_nonio.tcc	44.22 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
mask_array.h	7.42 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
memoryfwd.h	2.40 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
move.h	6.38 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
nested_exception.h	4.69 KB	lrw-r--r--	2025-08-26 09:45:07	Edit Download recursive recursive
node_handle.h	8.02 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
ostream.tcc	12.03 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
ostream_insert.h	3.91 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
parse_numbers.h	7.76 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
postypes.h	8.02 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
predefined_ops.h	8.87 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
ptr_traits.h	6.47 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
quoted_string.h	4.93 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
random.h	171.14 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
random.tcc	103.12 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
range_access.h	9.79 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
refwrap.h	11.61 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex.h	95.12 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex.tcc	16.18 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_automaton.h	10.47 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_automaton.tcc	7.65 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_compiler.h	17.63 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_compiler.tcc	18.84 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_constants.h	14.36 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_error.h	4.79 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_executor.h	7.31 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_executor.tcc	18.40 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_scanner.h	6.92 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
regex_scanner.tcc	14.66 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
shared_ptr.h	22.88 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
shared_ptr_atomic.h	9.54 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
shared_ptr_base.h	53.01 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
slice_array.h	9.13 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
specfun.h	45.95 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
sstream.tcc	9.90 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
std_abs.h	3.19 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
std_function.h	22.71 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
std_mutex.h	9.08 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_algo.h	209.27 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_algobase.h	49.31 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_bvector.h	32.94 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_construct.h	7.22 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_deque.h	76.73 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_function.h	40.77 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_heap.h	19.73 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_iterator.h	41.30 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_iterator_base_funcs.h	7.99 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_iterator_base_types.h	8.48 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_list.h	65.97 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_map.h	51.55 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_multimap.h	40.58 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_multiset.h	34.97 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_numeric.h	13.51 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_pair.h	18.21 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_queue.h	23.51 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_raw_storage_iter.h	3.74 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_relops.h	4.49 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_set.h	35.28 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_stack.h	11.66 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_tempbuf.h	8.15 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_tree.h	73.15 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_uninitialized.h	27.06 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stl_vector.h	59.12 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
streambuf.tcc	4.81 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
streambuf_iterator.h	13.44 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stream_iterator.h	6.50 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
stringfwd.h	2.55 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
string_view.tcc	6.54 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
uniform_int_dist.h	9.84 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
unique_ptr.h	25.38 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
unordered_map.h	73.58 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
unordered_set.h	57.76 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
uses_allocator.h	6.37 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
valarray_after.h	22.12 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
valarray_array.h	21.30 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
valarray_array.tcc	7.08 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
valarray_before.h	18.08 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive
vector.tcc	28.95 KB	lrw-r--r--	2025-08-26 09:45:00	Edit Download recursive recursive