333 lines
9.5 KiB
C++
333 lines
9.5 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_HASHTABLE_H
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#define TEUCHOS_HASHTABLE_H
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/*! \file Teuchos_Hashtable.hpp
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\brief Templated hashtable class
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*/
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#include "Teuchos_ConfigDefs.hpp"
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#include "Teuchos_Array.hpp"
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#include "Teuchos_HashUtils.hpp"
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namespace Teuchos
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{
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using std::string;
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/** \ingroup Containers
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* \brief Helper class for Teuchos::Hashtable, representing a single <key, value> pair.
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*/
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template<class Key, class Value> class HashPair
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{
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public:
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//! Empty constructor
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inline HashPair() : key_(), value_() {;}
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//! Basic <key, value> constructor
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inline HashPair(const Key& key, const Value& value)
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: key_(key), value_(value) {;}
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//! Templated key variable
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Key key_;
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//! Templated value variable
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Value value_;
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};
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/**
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\ingroup Containers
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\brief Templated hashtable class.
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@author Kevin Long
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*/
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template<class Key, class Value> class Hashtable
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{
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public:
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//! Create an empty Hashtable
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inline Hashtable(int capacity=101, double rehashDensity = 0.8);
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//! Check for the presence of a key
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inline bool containsKey(const Key& key) const ;
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//! Get the value indexed by key
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inline const Value& get(const Key& key) const ;
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//! Put a new (key, value) pair in the table.
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inline void put(const Key& key, const Value& value);
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//! Remove from the table the element given by key.
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inline void remove(const Key& key);
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//! Get the number of elements in the table
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inline int size() const {return count_;}
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//! Get lists of keys and values in Array form
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inline void arrayify(Array<Key>& keys, Array<Value>& values) const ;
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//! Return the average degeneracy (average number of entries per hash code).
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inline double avgDegeneracy() const {return avgDegeneracy_;}
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//! Return the density of the hashtable (num entries / capacity)
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inline double density() const {return ((double)count_)/((double) capacity_);}
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//! Set the density at which to do a rehash
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inline void setRehashDensity(double rehashDensity);
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//! Write to a std::string
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inline std::string toString() const ;
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private:
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inline void rehash();
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inline int nextPrime(int newCap) const ;
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inline void accumulateAvgFill(int n) const ;
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Array<Array<HashPair<Key, Value> > > data_;
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int count_;
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int capacity_;
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mutable Value mostRecentValue_;
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mutable Key mostRecentKey_;
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mutable int nHits_;
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mutable double avgDegeneracy_;
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double rehashDensity_;
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};
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template<class Key, class Value>
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std::string toString(const Hashtable<Key, Value>& h);
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/** \relates Hashtable
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\brief Write Hashtable to a stream
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*/
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template<class Key, class Value>
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std::ostream& operator<<(std::ostream& os, const Hashtable<Key, Value>& h);
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template<class Key, class Value> inline
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Hashtable<Key, Value>::Hashtable(int capacity, double rehashDensity)
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: data_(), count_(0), capacity_(HashUtils::nextPrime(capacity)),
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nHits_(0), avgDegeneracy_(0), rehashDensity_(rehashDensity)
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{
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data_.resize(capacity_);
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}
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template<class Key, class Value> inline
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bool Hashtable<Key, Value>::containsKey(const Key& key) const
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{
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const Array<HashPair<Key, Value> >& candidates
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= data_[hashCode(key) % capacity_];
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for (int i=0; i<candidates.length(); i++)
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{
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const HashPair<Key, Value>& c = candidates[i];
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if (c.key_ == key)
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{
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// (Key&) mostRecentKey_ = key;
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//(Value&) mostRecentValue_ = c.value_;
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return true;
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}
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}
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return false;
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}
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template<class Key, class Value> inline
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void Hashtable<Key, Value>::put(const Key& key, const Value& value)
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{
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int index = hashCode(key) % capacity_;
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Array<HashPair<Key, Value> >& local = data_[index];
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// check for duplicate key
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for (int i=0; i<local.length(); i++)
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{
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if (local[i].key_ == key)
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{
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local[i].value_ = value;
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return;
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}
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}
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// no duplicate key, so increment element count by one.
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count_++;
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// check for need to resize.
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if ((double) count_ > rehashDensity_ * (double) capacity_)
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{
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capacity_ = HashUtils::nextPrime(capacity_+1);
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rehash();
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// recaluate index
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index = hashCode(key) % capacity_;
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}
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data_[index].append(HashPair<Key, Value>(key, value));
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}
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template<class Key, class Value> inline
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void Hashtable<Key, Value>::rehash()
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{
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Array<Array<HashPair<Key, Value> > > tmp(capacity_);
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for (int i=0; i<data_.length(); i++)
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{
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for (int j=0; j<data_[i].length(); j++)
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{
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int newIndex = hashCode(data_[i][j].key_) % capacity_;
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tmp[newIndex].append(data_[i][j]);
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}
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}
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data_ = tmp;
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}
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template<class Key, class Value> inline
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void Hashtable<Key, Value>::arrayify(Array<Key>& keys, Array<Value>& values) const
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{
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keys.reserve(size());
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values.reserve(size());
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for (int i=0; i<data_.length(); i++)
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{
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for (int j=0; j<data_[i].length(); j++)
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{
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keys.append(data_[i][j].key_);
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values.append(data_[i][j].value_);
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}
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}
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}
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template<class Key, class Value> inline
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std::string Hashtable<Key, Value>::toString() const
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{
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Array<Key> keys;
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Array<Value> values;
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arrayify(keys, values);
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std::string rtn = "[";
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for (int i=0; i<keys.length(); i++)
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{
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rtn += "{" + Teuchos::toString(keys[i]) + ", " + Teuchos::toString(values[i])
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+ "}";
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if (i < keys.length()-1) rtn += ", ";
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}
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rtn += "]";
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return rtn;
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}
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template<class Key, class Value> inline
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std::string toString(const Hashtable<Key, Value>& h)
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{
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Array<Key> keys;
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Array<Value> values;
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h.arrayify(keys, values);
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std::string rtn = "[";
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for (int i=0; i<keys.length(); i++)
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{
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rtn += "{" + Teuchos::toString(keys[i]) + ", " + Teuchos::toString(values[i])
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+ "}";
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if (i < keys.length()-1) rtn += ", ";
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}
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rtn += "]";
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return rtn;
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}
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template<class Key, class Value> inline
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const Value& Hashtable<Key, Value>::get(const Key& key) const
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{
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TEST_FOR_EXCEPTION(!containsKey(key),
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std::runtime_error,
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"Hashtable<Key, Value>::get: key "
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<< Teuchos::toString(key)
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<< " not found in Hashtable"
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<< toString());
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const Array<HashPair<Key, Value> >& candidates
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= data_[hashCode(key) % capacity_];
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accumulateAvgFill(candidates.length());
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for (int i=0; i<candidates.length(); i++)
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{
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const HashPair<Key, Value>& c = candidates[i];
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if (c.key_ == key)
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{
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return c.value_;
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}
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}
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return mostRecentValue_;
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}
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template<class Key, class Value> inline
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void Hashtable<Key, Value>::remove(const Key& key)
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{
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TEST_FOR_EXCEPTION(!containsKey(key),
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std::runtime_error,
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"Hashtable<Key, Value>::remove: key "
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<< Teuchos::toString(key)
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<< " not found in Hashtable"
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<< toString());
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count_--;
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int h = hashCode(key) % capacity_;
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const Array<HashPair<Key, Value> >& candidates = data_[h];
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for (int i=0; i<candidates.length(); i++)
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{
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const HashPair<Key, Value>& c = candidates[i];
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if (c.key_ == key)
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{
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data_[h].remove(i);
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break;
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}
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}
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}
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template<class Key, class Value> inline
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void Hashtable<Key, Value>::accumulateAvgFill(int n) const
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{
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avgDegeneracy_ = ((double) nHits_)/(nHits_ + 1.0) * avgDegeneracy_ + ((double) n)/(nHits_ + 1.0);
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nHits_++;
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}
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template<class Key, class Value> inline
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std::ostream& operator<<(std::ostream& os, const Hashtable<Key, Value>& h)
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{
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return os << toString(h);
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}
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}
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#endif // TEUCHOS_HASHTABLE_H
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