URL
https://opencores.org/ocsvn/openrisc_2011-10-31/openrisc_2011-10-31/trunk
Subversion Repositories openrisc_2011-10-31
[/] [openrisc/] [tags/] [gnu-src/] [gcc-4.5.1/] [gcc-4.5.1-or32-1.0rc3/] [libstdc++-v3/] [testsuite/] [ext/] [pb_ds/] [example/] [store_hash.cc] - Rev 424
Go to most recent revision | Compare with Previous | Blame | View Log
// -*- C++ -*- // Copyright (C) 2005, 2006, 2009 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 3, 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 COPYING3. If not see // <http://www.gnu.org/licenses/>. // 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 store_hash_example.cpp * An example showing how to store hash-values with * each entry in a hash-based container. */ /** * This example shows how to configure a hash-based container to store * the hash value of each key along with each entry. This technique * is useful for complex keys (e.g., strings in this example), since * it lowers the cost of collisions. For simpler types (e.g., integers), * where the cost of comparing keys is of the same order as the cost * of comparing hash values, this technique adds unnecessary overhead. */ #include <functional> #include <string> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/hash_policy.hpp> using namespace std; using namespace __gnu_pbds; // A string hash functor. struct string_hash : public unary_function<string, size_t> { inline size_t operator()(string str) const { string::const_iterator b = str.begin(); string::const_iterator e = str.end(); size_t hash = 0; while (b != e) { hash *= 5; hash += static_cast<size_t>(*b); ++b; } return hash; } }; int main() { // A collision-chaining hash table mapping strings to ints. typedef cc_hash_table< string, int, string_hash, equal_to<string>, direct_mask_range_hashing<>, hash_standard_resize_policy<>, true> map_t; map_t h; // Use regularly. h["Hello, "] = 0; h["world"] = 1; return 0; }
Go to most recent revision | Compare with Previous | Blame | View Log