libstdc++-v3/testsuite/util/hash_fn/string_ranged_hash_fn.hpp

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005-2019 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 // You should have received a copy of the GNU General Public License
  17 // along with this library; see the file COPYING3.  If not see
  18 // <http://www.gnu.org/licenses/>.
  19
  20
  21 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  22
  23 // Permission to use, copy, modify, sell, and distribute this software
  24 // is hereby granted without fee, provided that the above copyright
  25 // notice appears in all copies, and that both that copyright notice
  26 // and this permission notice appear in supporting documentation. None
  27 // of the above authors, nor IBM Haifa Research Laboratories, make any
  28 // representation about the suitability of this software for any
  29 // purpose. It is provided "as is" without express or implied
  30 // warranty.
  31
  32 /**
  33  * @file string_ranged_hash_fn.hpp
  34  * Contains a ranged string hash function.
  35  */
  36
  37 #ifndef PB_DS_STRING_RANGED_HASH_FN_HPP
  38 #define PB_DS_STRING_RANGED_HASH_FN_HPP
  39
  40 #include <string>
  41 #include <hash_fn/dna_str_limit.hpp>
  42
  43 namespace __gnu_pbds
  44 {
  45   namespace test
  46   {
  47     template<typename Comb_Fn>
  48     class string_ranged_hash_fn : public Comb_Fn
  49     {
  50     private:
  51       size_t _M_limit;
  52
  53     public:
  54       typedef Comb_Fn comb_fn;
  55       typedef detail::comb_hash_fn_string_form<comb_fn> string_form;
  56
  57       inline size_t
  58       operator()(const std::string& r_str) const
  59       {
  60         size_t ret = 0;
  61         std::string::const_iterator b = r_str.begin();
  62         std::string::const_iterator e = r_str.end();
  63
  64         size_t i = 0;
  65         while (i < _M_limit&&  b != e)
  66           {
  67             ret *= 5;
  68             ret += static_cast<size_t>(*(b++));
  69             ++i;
  70           }
  71         return (comb_fn::operator()(ret));
  72       }
  73
  74       void
  75       swap(string_ranged_hash_fn<Comb_Fn>& other)
  76       {
  77         std::swap(_M_limit, other._M_limit);
  78         comb_fn::swap(other);
  79       }
  80
  81       void
  82       notify_resized(size_t new_size)
  83       {
  84         comb_fn::notify_resized(new_size);
  85         _M_limit = dna_str_limit(new_size);
  86       }
  87
  88       static std::string
  89       name()
  90       { return ("string_ranged_hash_fn_" + string_form<comb_fn>::name()); }
  91
  92       static std::string
  93       desc()
  94       { return ("string ranged-hash using" + string_form<comb_fn>::desc()); }
  95     };
  96   } // namespace test
  97 } // namespace __gnu_pbds
  98
  99 #endif