// -*- C++ -*- // Copyright (C) 2005, 2006 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the terms // of the GNU General Public License as published by the Free Software // Foundation; either version 2, or (at your option) any later // version. // This library is distributed in the hope that it will be useful, but // WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU // General Public License for more details. // You should have received a copy of the GNU General Public License // along with this library; see the file COPYING. If not, write to // the Free Software Foundation, 59 Temple Place - Suite 330, Boston, // MA 02111-1307, USA. // As a special exception, you may use this file as part of a free // software library without restriction. Specifically, if other files // instantiate templates or use macros or inline functions from this // file, or you compile this file and link it with other files to // produce an executable, this file does not by itself cause the // resulting executable to be covered by the GNU General Public // License. This exception does not however invalidate any other // reasons why the executable file might be covered by the GNU General // Public License. // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. // Permission to use, copy, modify, sell, and distribute this software // is hereby granted without fee, provided that the above copyright // notice appears in all copies, and that both that copyright notice // and this permission notice appear in supporting documentation. None // of the above authors, nor IBM Haifa Research Laboratories, make any // representation about the suitability of this software for any // purpose. It is provided "as is" without express or implied // warranty. /** * @file hash_resize_example.cpp * An example of externally resizing a map. */ /** * This example shows how to externally manipulate the size of a hash-based * container object throught its resize-policy object. **/ #include <functional> #include <cassert> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/hash_policy.hpp> using namespace std; using namespace pb_ds; // A simple hash functor. // hash could serve instead of this functor, but it is not yet // standard everywhere. struct int_hash : public unary_function<int, size_t> { inline size_t operator()(const int& r_i) const { return r_i; } }; int main() { // A probing hash table mapping ints to chars. typedef gp_hash_table< int, char, int_hash, equal_to< int>, // Combining function. direct_mask_range_hashing<>, // Probe function. linear_probe_fn<>, // Resize policy. hash_standard_resize_policy< hash_exponential_size_policy<>, hash_load_check_resize_trigger<>, /* Allow external access to size. * Without setting this to true, external resizing * is not possible. */ true> > map_t; map_t g; // Check the actual size of the container object. In this case, this // should be the initial size given by the size policy object. assert(g.get_actual_size() == 8); // Insert some elements. g[1] = 'a'; g[2] = 'b'; g[3] = 'c'; // Now resize the table upward. g.resize(200); // Check the actual size of the container object. // For the policy used in this example, the nearest larger size than // 200 is 256. assert(g.get_actual_size() == 256); g[67] = 'g'; g[22] = 'f'; // Regardless of the internal size, the logical size should be 5. assert(g.size() == 5); // Now resize the table downward. g.resize(106); // Check the actual size of the container object. // For the policy used in this example, the nearest larger size than // 106 is 128. assert(g.get_actual_size() == 128); g[37] = 'f'; // Regardless of the internal size, the logical size should be 5. assert(g.size() == 6); return 0; }