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83 lines
2.4 KiB
C++
83 lines
2.4 KiB
C++
//
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// HashFunction.h
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//
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// $Id: //poco/1.2/Foundation/include/Poco/HashFunction.h#1 $
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//
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// Library: Foundation
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// Package: Core
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// Module: HashFunction
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//
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// Definition of the HashFunction class.
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//
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// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// Permission is hereby granted, free of charge, to any person or organization
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// obtaining a copy of the software and accompanying documentation covered by
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// this license (the "Software") to use, reproduce, display, distribute,
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// execute, and transmit the Software, and to prepare derivative works of the
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// Software, and to permit third-parties to whom the Software is furnished to
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// do so, all subject to the following:
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//
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// The copyright notices in the Software and this entire statement, including
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// the above license grant, this restriction and the following disclaimer,
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// must be included in all copies of the Software, in whole or in part, and
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// all derivative works of the Software, unless such copies or derivative
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// works are solely in the form of machine-executable object code generated by
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// a source language processor.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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//
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#ifndef Foundation_HashFunction_INCLUDED
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#define Foundation_HashFunction_INCLUDED
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#include "Poco/Foundation.h"
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namespace Poco {
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template <class T>
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struct HashFunction
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/// A generic hash function for numeric values.
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{
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static UInt32 hash(T key, UInt32 maxValue)
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/// Returns the hash value for the given key
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{
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return key * 0xf4243 % maxValue;
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}
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};
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template <>
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struct HashFunction<std::string>
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/// A specialization of HashFunction for strings.
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{
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static UInt32 hash(const std::string& key, UInt32 maxValue)
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{
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// hash function taken from XML expat
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UInt32 h = 0;
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for (int i = 0; i < key.length(); ++i)
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{
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h = h * 0xf4243 ^ key[i];
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}
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return h % maxValue;
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}
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};
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} // namespace Poco
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#endif // Foundation_HashFunctions_INCLUDED
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