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_resize_example.cpp 42 * An example of externally resizing a map. 43 */ 44 45// For gp_hash_assoc_cntnr. 46#include <ext/pb_assoc/assoc_cntnr.hpp> 47// For hash-related policies. 48#include <ext/pb_assoc/hash_policy.hpp> 49// For unary_function. 50#include <functional> 51// For assert 52#include <cassert> 53 54/* 55 * A simple hash functor. 56 * std::hash could serve instead of this functor, 57 * but it is not yet standard everywhere. 58 */ 59struct int_hash : public std::unary_function< 60 int, 61 size_t> 62{ 63 inline size_t 64 operator()(const int& r_i) const 65 { 66 return (r_i); 67 } 68}; 69 70int 71main() 72{ 73 /* 74 * A probing hash table mapping ints to chars. 75 */ 76 typedef 77 pb_assoc::gp_hash_assoc_cntnr< 78 int, 79 char, 80 int_hash, 81 std::equal_to< 82 int>, 83 // Combining function. 84 pb_assoc::direct_mask_range_hashing<>, 85 // Probe function. 86 pb_assoc::linear_probe_fn< 87 int>, 88 // Resize policy. 89 pb_assoc::hash_standard_resize_policy< 90 pb_assoc::hash_exponential_size_policy<>, 91 pb_assoc::hash_load_check_resize_trigger<>, 92 /* Allow external access to size. 93 * Without setting this to true, external resizing 94 * is not possible. 95 */ 96 true> > 97 map_t; 98 99 map_t g; 100 101 /* 102 * Check the actual size of the container object. In this case, 103 * this should be the initial size given by the size policy object. 104 **/ 105 assert(g.get_actual_size() == 8); 106 107 // Insert some elements. 108 109 g[1] = 'a'; 110 g[2] = 'b'; 111 g[3] = 'c'; 112 113 // Now resize the table upward. 114 115 g.resize(200); 116 117 /* 118 * Check the actual size of the container object. 119 * For the policy used in this example, the 120 * nearest larger size than 200 is 256. 121 **/ 122 assert(g.get_actual_size() == 256); 123 124 g[67] = 'g'; 125 g[22] = 'f'; 126 127 // Regardless of the internal size, the logical size should be 5. 128 assert(g.size() == 5); 129 130 // Now resize the table downward. 131 132 g.resize(106); 133 134 /* 135 * Check the actual size of the container object. 136 * For the policy used in this example, the 137 * nearest larger size than 106 is 128. 138 **/ 139 assert(g.get_actual_size() == 128); 140 141 g[37] = 'f'; 142 143 // Regardless of the internal size, the logical size should be 5. 144 assert(g.size() == 6); 145} 146 147