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 gp_ht_map_resize_example.cpp 42 * An example of setting an initial size for a container object. 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 assert 50#include <cassert> 51 52/* 53 * A simple hash functor. 54 * std::hash could serve instead of this functor, 55 * but it is not yet standard everywhere. 56 */ 57struct int_hash : public std::unary_function< 58 int, 59 size_t> 60{ 61 inline size_t 62 operator()(const int& r_i) const 63 { 64 return (r_i); 65 } 66}; 67 68int 69main() 70{ 71 // Resize policy type. 72 typedef 73 pb_assoc::hash_standard_resize_policy< 74 // Size-policy type. 75 pb_assoc::hash_exponential_size_policy<>, 76 // Trigger-policy type. 77 pb_assoc::hash_load_check_resize_trigger<>, 78 /* Allow external access to size. 79 * This is just used in this example for using the 80 * get_actual_size method (which won't be accessible without 81 * this flag. 82 */ 83 true> 84 resize_policy_t; 85 86 /* 87 * A collision-probing hash table mapping ints to chars. 88 */ 89 typedef 90 pb_assoc::gp_hash_assoc_cntnr< 91 int, 92 char, 93 int_hash, 94 std::equal_to< 95 int>, 96 // Combining function. 97 pb_assoc::direct_mask_range_hashing<>, 98 // Probe function. 99 pb_assoc::linear_probe_fn< 100 const int& >, 101 // Resize policy. 102 resize_policy_t> 103 map_t; 104 105 // A resize-policy object with suggested initial size 256. 106 resize_policy_t res(pb_assoc::hash_exponential_size_policy<>(256)); 107 108 map_t g(int_hash(), 109 std::equal_to<int>(), 110 pb_assoc::direct_mask_range_hashing<>(), 111 pb_assoc::linear_probe_fn<const int& >(), 112 res); 113 114 /* 115 * Check the actual size of the container object. In this case, 116 * this should be the initial size given by the size policy object. 117 **/ 118 assert(g.get_actual_size() >= 256); 119 120 assert(g.size() == 0); 121} 122 123