1// -*- C++ -*- 2 3// Copyright (C) 2005 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 7// terms of the GNU General Public License as published by the 8// Free Software Foundation; either version 2, or (at your option) 9// any later version. 10 11// This library is distributed in the hope that it will be useful, 12// but WITHOUT ANY WARRANTY; without even the implied warranty of 13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14// GNU General Public License for more details. 15 16// You should have received a copy of the GNU General Public License along 17// with this library; see the file COPYING. If not, write to the Free 18// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 19// USA. 20 21// As a special exception, you may use this file as part of a free software 22// library without restriction. Specifically, if other files instantiate 23// templates or use macros or inline functions from this file, or you compile 24// this file and link it with other files to produce an executable, this 25// file does not by itself cause the resulting executable to be covered by 26// the GNU General Public License. This exception does not however 27// invalidate any other reasons why the executable file might be covered by 28// the GNU General Public License. 29 30// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. 31 32// Permission to use, copy, modify, sell, and distribute this software 33// is hereby granted without fee, provided that the above copyright 34// notice appears in all copies, and that both that copyright notice and 35// this permission notice appear in supporting documentation. None of 36// the above authors, nor IBM Haifa Research Laboratories, make any 37// representation about the suitability of this software for any 38// purpose. It is provided "as is" without express or implied warranty. 39 40/** 41 * @file hash_mod_example.cpp 42 * An example showing how to use cc_ht_map with alternative policies. 43 */ 44 45// For cc_hash_assoc_cntnr. 46#include <ext/pb_assoc/assoc_cntnr.hpp> 47// For direct_mask_range_hashing and hash_standard_resize_policy. 48#include <ext/pb_assoc/hash_policy.hpp> 49// For unary_function, binary_function. 50#include <functional> 51// For string. 52#include <string> 53 54/* 55 * A string hash functor 56 */ 57struct string_hash : public std::unary_function< 58 std::string, 59 size_t> 60{ 61 inline size_t 62 operator()(std::string str) const 63 { 64 std::string::const_iterator b = str.begin(); 65 66 std::string::const_iterator e = str.end(); 67 68 size_t hash = 0; 69 70 while (b != e) 71 { 72 hash *= 5; 73 74 hash += static_cast<size_t>(*b); 75 76 ++b; 77 } 78 79 return (hash); 80 } 81}; 82 83int 84main() 85{ 86 /* 87 * A collision-chaining hash table mapping strings to ints. 88 */ 89 typedef 90 pb_assoc::cc_hash_assoc_cntnr< 91 std::string, 92 int, 93 // Hash function. 94 string_hash, 95 // Equivalence function. 96 std::equal_to< 97 std::string>, 98 // Range hashing function. 99 pb_assoc::direct_mask_range_hashing<>, 100 // Resize policy. 101 pb_assoc::hash_standard_resize_policy<>, 102 // Store the hash value with each entry. 103 true> 104 map_t; 105 106 map_t h; 107 108 h["Hello, "] = 0; 109 h["world"] = 1; 110} 111 112