| // -*- 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; |
| } |
| |