libstdc++-v3/include/ext/pb_ds/detail/eq_fn/hash_eq_fn.hpp

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005-2023 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the terms
   7 // of the GNU General Public License as published by the Free Software
   8 // Foundation; either version 3, or (at your option) any later
   9 // version.
  10
  11 // This library is distributed in the hope that it will be useful, but
  12 // WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 // General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  26
  27 // Permission to use, copy, modify, sell, and distribute this software
  28 // is hereby granted without fee, provided that the above copyright
  29 // notice appears in all copies, and that both that copyright notice
  30 // and this permission notice appear in supporting documentation. None
  31 // of the above authors, nor IBM Haifa Research Laboratories, make any
  32 // representation about the suitability of this software for any
  33 // purpose. It is provided "as is" without express or implied
  34 // warranty.
  35
  36 /**
  37  * @file hash_eq_fn.hpp
  38  * Contains 2 equivalence functions, one employing a hash value,
  39  * and one ignoring it.
  40  */
  41
  42 #ifndef PB_DS_HASH_EQ_FN_HPP
  43 #define PB_DS_HASH_EQ_FN_HPP
  44
  45 #include <utility>
  46 #include <ext/pb_ds/detail/types_traits.hpp>
  47 #include <debug/debug.h>
  48
  49 namespace __gnu_pbds
  50 {
  51   namespace detail
  52   {
  53     /// Primary template.
  54     template<typename Key, typename Eq_Fn, typename _Alloc, bool Store_Hash>
  55       struct hash_eq_fn;
  56
  57     /// Specialization 1 - The client requests that hash values not be stored.
  58     template<typename Key, typename Eq_Fn, typename _Alloc>
  59     struct hash_eq_fn<Key, Eq_Fn, _Alloc, false> : public Eq_Fn
  60     {
  61       typedef Eq_Fn                                        eq_fn_base;
  62       typedef typename rebind_traits<_Alloc, Key>::const_reference
  63         key_const_reference;
  64
  65       hash_eq_fn() { }
  66
  67       hash_eq_fn(const Eq_Fn& r_eq_fn) : Eq_Fn(r_eq_fn) { }
  68
  69       bool
  70       operator()(key_const_reference r_lhs_key,
  71                  key_const_reference r_rhs_key) const
  72       { return eq_fn_base::operator()(r_lhs_key, r_rhs_key); }
  73
  74       void
  75       swap(const hash_eq_fn& other)
  76       { std::swap((Eq_Fn&)(*this), (Eq_Fn&)other); }
  77     };
  78
  79
  80     /// Specialization 2 - The client requests that hash values be stored.
  81     template<typename Key, class Eq_Fn, class _Alloc>
  82     struct hash_eq_fn<Key, Eq_Fn, _Alloc, true> : public Eq_Fn
  83     {
  84       typedef typename _Alloc::size_type                   size_type;
  85       typedef Eq_Fn                                        eq_fn_base;
  86       typedef typename rebind_traits<_Alloc, Key>::const_reference
  87         key_const_reference;
  88
  89       hash_eq_fn() { }
  90
  91       hash_eq_fn(const Eq_Fn& r_eq_fn) : Eq_Fn(r_eq_fn) { }
  92
  93       bool
  94       operator()(key_const_reference r_lhs_key, size_type lhs_hash,
  95                  key_const_reference r_rhs_key, size_type rhs_hash) const
  96       {
  97         _GLIBCXX_DEBUG_ASSERT(!eq_fn_base::operator()(r_lhs_key, r_rhs_key)
  98                               || lhs_hash == rhs_hash);
  99
 100         return (lhs_hash == rhs_hash &&
 101                 eq_fn_base::operator()(r_lhs_key, r_rhs_key));
 102       }
 103
 104       void
 105       swap(const hash_eq_fn& other)
 106       { std::swap((Eq_Fn&)(*this), (Eq_Fn&)(other)); }
 107     };
 108   } // namespace detail
 109 } // namespace __gnu_pbds
 110
 111 #endif