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[/] [scarts/] [trunk/] [toolchain/] [scarts-gcc/] [gcc-4.1.1/] [libstdc++-v3/] [testsuite/] [ext/] [pb_assoc/] [example/] [hash_shift_mask.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_shift_mask_example.cpp * An example showing how to write a range-hasing functor. */ // For cc_hash_assoc_cntnr. #include <ext/pb_assoc/assoc_cntnr.hpp> // For hash-related policies. #include <ext/pb_assoc/hash_policy.hpp> // For unary_function and binary_function #include <functional> /* * A simple hash functor. * std::hash could serve instead of this functor, * but it is not yet standard everywhere. */ struct simple_int_hash : public std::unary_function< int, size_t> { inline size_t operator()(int i) const { return (i); } }; // A range-hashing function which shifts 2 bits right and then masks. class shift_two_mask_range_hashing : private pb_assoc::direct_mask_range_hashing<> { public: typedef size_t size_type; public: /* * Swaps with a different instant. */ void swap(shift_two_mask_range_hashing& r_other) { pb_assoc::direct_mask_range_hashing<>::swap(r_other); } /* * Called by the container when internally resized. */ void notify_resized(size_type size) { pb_assoc::direct_mask_range_hashing<>::notify_resized(size); } /* * Given a hash value, returns a number in the range of the * internal size of the container. */ inline size_type operator()(size_type hash) const { return (pb_assoc::direct_mask_range_hashing<>::operator()( hash >> 2)); } }; int main() { /* * A collision-chaining hash table mapping ints to chars. */ typedef pb_assoc::cc_hash_assoc_cntnr< int, char, // Hash function. simple_int_hash, std::equal_to<int>, // Range hashing function. shift_two_mask_range_hashing> map_t; map_t h; // Use normally. h[16] = 'a'; h[256] = 'e'; h[4] = 'z'; }