122 lines
3.2 KiB
C++
122 lines
3.2 KiB
C++
// @HEADER
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// ***********************************************************************
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//
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// Teuchos: Common Tools Package
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// Copyright (2004) Sandia Corporation
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//
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// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
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// license for use of this work by or on behalf of the U.S. Government.
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//
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// This library is free software; you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; either version 2.1 of the
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// License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
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// USA
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// Questions? Contact Michael A. Heroux (maherou@sandia.gov)
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//
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// ***********************************************************************
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// @HEADER
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#ifndef TEUCHOS_HASHUTILS_H
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#define TEUCHOS_HASHUTILS_H
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/*! \file Teuchos_HashUtils.hpp
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\brief Utilities for generating hashcodes
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*/
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#include "Teuchos_ConfigDefs.hpp"
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namespace Teuchos
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{
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using std::string;
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/**
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* \ingroup Containers
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* \brief Utilities for generating hashcodes.
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*/
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class HashUtils
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{
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public:
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/* Get the next prime in a sequence of hashtable sizes */
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static int nextPrime(int newCapacity);
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private:
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// sequence of primes generated via mathematica:
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// Table[Prime[Round[1.5^x]], {x, 8, 36}]
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static const int primeCount_;
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static const int primes_[];
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/*={101, 163, 271, 443, 733, 1187, 1907, 3061,
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4919, 7759, 12379, 19543, 30841, 48487, 75989,
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119089, 185971, 290347, 452027, 703657, 1093237,
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1695781, 2627993, 4067599, 6290467, 9718019,
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15000607, 23133937, 35650091};*/
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};
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/** \relates HashUtils
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\brief Standard interface for getting the hash code of an object
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*/
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template <class T> int hashCode(const T& x);
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/** \relates HashUtils
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\brief Get the hash code of an int
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*/
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template <> inline int hashCode(const int& x)
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{
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return x;
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}
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/** \relates HashUtils
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\brief Get the hash code of a double
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*/
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template <> inline int hashCode(const double& x)
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{
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return (int) x;
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}
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/** \relates HashUtils
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\brief Get the hash code of a bool
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*/
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template <> inline int hashCode(const bool& x)
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{
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return (int) x;
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}
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/** \relates HashUtils
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\brief Get the hash code of a std::string
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*/
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template <> inline int hashCode(const std::string& x)
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{
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const char* str = x.c_str();
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int len = x.length();
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int step = len/4 + 1;
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int base = 1;
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int rtn = 0;
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for (int i=0; i<len/2; i+=step)
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{
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rtn += base*(int) str[i];
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base *= 128;
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rtn += base*(int) str[len-i-1];
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base *= 128;
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}
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return rtn;
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}
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}
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#endif // TEUCHOS_HASHUTILS_H
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