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/*
* $Revision: 2615 $
*
* last checkin:
* $Author: gutwenger $
* $Date: 2012-07-16 14:23:36 +0200 (Mo, 16. Jul 2012) $
***************************************************************/
/** \file
* \brief Declaration and implementation of HashArray class.
*
* \author Carsten Gutwenger
*
* \par License:
* This file is part of the Open Graph Drawing Framework (OGDF).
*
* \par
* Copyright (C)<br>
* See README.txt in the root directory of the OGDF installation for details.
*
* \par
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* Version 2 or 3 as published by the Free Software Foundation;
* see the file LICENSE.txt included in the packaging of this file
* for details.
*
* \par
* This program 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.
*
* \par
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
* \see http://www.gnu.org/copyleft/gpl.html
***************************************************************/
#ifdef _MSC_VER
#pragma once
#endif
#ifndef OGDF_HASH_ARRAY_H
#define OGDF_HASH_ARRAY_H
#include "Hashing.h"
namespace ogdf {
//! Indexed arrays using hashing for element access.
/**
* @tparam I is the index type.
* @tparam E is the element type.
* @tparam H is the hash function type. Optional; its default uses the class DefHashFunc.
*
* A hashing array can be used like a usual array but has a general
* index type.
*
* The hashing array is only defined for a subset <I>I<SUB>def</SUB></I> of the
* index set (set of all elements of the index type). At construction, this set
* is empty. Whenever an index is assigned an element, this index is added
* to <I>I<SUB>def</SUB></I>. There are also method for testing if an index
* is defined (is in <I>I<SUB>def</SUB></I>).
*
* <H3>Example</H3>
* The following code snippet demonstrates how to use a hashing array. First,
* the example inserts elements into a hashing array simulating a tiny
* German–English dictionary, then it prints some elements via array
* access, and finally it iterates over all defined indices and prints the
* dictionary entries. We use a the const reference \a Hc, since we want to
* avoid that array access for undefined indices creates these elements.
*
* \code
* HashArray<String,String> H("[undefined]");
* const HashArray<String,String> &Hc = H;
*
* H["Hund"] = "dog";
* H["Katze"] = "cat";
* H["Maus"] = "mouse";
*
* cout << "Katze: " << Hc["Katze"] << endl;
* cout << "Hamster: " << Hc["Hamster"] << endl;
*
* cout << "\nAll elements:" << endl;
* HashConstIterator<String,String> it;
* for(it = Hc.begin(); it.valid(); ++it)
* cout << it.key() << " -> " << it.info() << endl;
* \endcode
*
* The produced output is as follows:
* \code
* Katze: cat
* Hamster: [undefined]
*
* All elements:
* Hund -> dog
* Maus -> mouse
* Katze -> cat
* \endcode
*/
template<class I, class E, class H = DefHashFunc<I> >
class HashArray : private Hashing<I,E,H>
{
E m_defaultValue; //! The default value for elements.
public:
//! The type of const-iterators for hash arrays.
typedef HashConstIterator<I,E,H> const_iterator;
//! Creates a hashing array; the default value is the default value of the element type.
HashArray() : Hashing<I,E,H>() { }
//! Creates a hashing array with default value \a defaultValue.
HashArray(const E &defaultValue, const H &hashFunc = H())
: Hashing<I,E,H>(256, hashFunc), m_defaultValue(defaultValue) { }
//! Copy constructor.
HashArray(const HashArray<I,E,H> &A) : Hashing<I,E,H>(A), m_defaultValue(A.m_defaultValue) { }
//! Returns an iterator to the first element in the list of all elements.
HashConstIterator<I,E,H> begin() const { return Hashing<I,E,H>::begin(); }
//! Returns the number of defined indices (= number of elements in hash table).
int size() const { return Hashing<I,E,H>::size(); }
//! Returns if any indices are defined (= if the hash table is empty)
int empty() const { return Hashing<I,E,H>::empty(); }
//! Returns the element with index \a i.
const E &operator[](const I &i) const {
HashElement<I,E> *pElement = Hashing<I,E,H>::lookup(i);
if (pElement) return pElement->info();
else return m_defaultValue;
}
//! Returns a reference to the element with index \a i.
E &operator[](const I &i) {
HashElement<I,E> *pElement = Hashing<I,E,H>::lookup(i);
if (!pElement) pElement = Hashing<I,E,H>::fastInsert(i,m_defaultValue);
return pElement->info();
}
//! Returns true iff index \a i is defined.
bool isDefined(const I &i) const {
return Hashing<I,E,H>::member(i);
}
//! Undefines index \a i.
void undefine(const I &i) {
Hashing<I,E,H>::del(i);
}
//! Assignment operator.
HashArray<I,E,H> &operator=(const HashArray<I,E,H> &A) {
m_defaultValue = A.m_defaultValue;
Hashing<I,E,H>::operator =(A);
return *this;
}
//! Undefines all indices.
void clear() { Hashing<I,E,H>::clear(); }
};
} // end namespace ogdf
#endif
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