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[/] [scarts/] [trunk/] [toolchain/] [scarts-gcc/] [gcc-4.1.1/] [libstdc++-v3/] [testsuite/] [ext/] [pb_assoc/] [example/] [hash_load_set_change.cc] - Rev 19
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// -*- C++ -*- // Copyright (C) 2005 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, // 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_load_set_change_example.cpp * An example of setting and changing the load factor of a hash-based * container object. */ // For cc_hash_assoc_cntnr. #include <ext/pb_assoc/assoc_cntnr.hpp> /* * For hash_standard_resize_policy, hash_exponential_size_policy, * and direct_mask_range_hashing. */ #include <ext/pb_assoc/hash_policy.hpp> // For unary_function. #include <functional> // For assert #include <cassert> /* * A simple hash functor. * std::hash could serve instead of this functor, * but it is not yet standard everywhere. */ struct int_hash : public std::unary_function< int, size_t> { inline size_t operator()(int i) const { return (i); } }; int main() { // A trigger policy type. typedef pb_assoc::hash_load_check_resize_trigger< true> trigger_t; // A resize policy type. typedef pb_assoc::hash_standard_resize_policy< pb_assoc::hash_exponential_size_policy<>, // Trigger type. trigger_t, /* Allow external access to size. * This is not necessary for setting the load factor, * but it allows to call get_actual_size. */ true> resize_t; /* * A collision-chaining hash table mapping ints to chars. */ typedef pb_assoc::cc_hash_assoc_cntnr< int, char, int_hash, std::equal_to<int>, // Combining function. pb_assoc::direct_mask_range_hashing<>, // Resize policy. resize_t> map_t; // A trigger policy object with load between 0.3 and 0.8. trigger_t trigger(static_cast<float>(0.3), static_cast<float>(0.8)); // A resize policy object with the above trigger. resize_t resize(pb_assoc::hash_exponential_size_policy<>(), trigger); map_t c(int_hash(), std::equal_to<int>(), pb_assoc::direct_mask_range_hashing<>(), resize); c[1] = 'a'; // Check the loads and sizes. assert(c.get_loads().first == static_cast<float>(0.3)); assert(c.get_loads().second == static_cast<float>(0.8)); assert(c.get_actual_size() == 8); assert(c.size() == 1); /* * Note that there is a discrepancy between the loads of the policy * object and the actual size of the container object. This is * because the container's construction performs an implicit external * resize. */ c[2] = 'b'; c[3] = 'c'; c[4] = 'd'; assert(c.get_actual_size() == 8); // Change the loads. This causes (potentially) a resize. c.set_loads(std::make_pair( static_cast<float>(0.01), static_cast<float>(0.05))); // The loads actually changed. assert(c.get_actual_size() > 8); }