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///////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2001, Eric D. Friedman All Rights Reserved.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, 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 Lesser General Public
// License along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
///////////////////////////////////////////////////////////////////////////////

package gnu.trove;

/**
 * Iterator for maps of type int and int.
 *
 * 

The iterator semantics for Trove's primitive maps is slightly different * from those defined in java.util.Iterator, but still well within * the scope of the pattern, as defined by Gamma, et al.

* *

This iterator does not implicitly advance to the next entry when * the value at the current position is retrieved. Rather, you must explicitly * ask the iterator to advance() and then retrieve either the key(), * the value() or both. This is done so that you have the option, but not * the obligation, to retrieve keys and/or values as your application requires, and * without introducing wrapper objects that would carry both. As the iteration is * stateful, access to the key/value parts of the current map entry happens in * constant time.

* *

In practice, the iterator is akin to a "search finger" that you move from * position to position. Read or write operations affect the current entry only and * do not assume responsibility for moving the finger.

* *

Here are some sample scenarios for this class of iterator:

* *
 * // accessing keys/values through an iterator:
 * for (TIntIntIterator it = map.iterator();
 *      it.hasNext();) {
 *   it.forward();
 *   if (satisfiesCondition(it.key()) {
 *     doSomethingWithValue(it.value());
 *   }
 * }
 * 
* *
 * // modifying values in-place through iteration:
 * for (TIntIntIterator it = map.iterator();
 *      it.hasNext();) {
 *   it.forward();
 *   if (satisfiesCondition(it.key()) {
 *     it.setValue(newValueForKey(it.key()));
 *   }
 * }
 * 
* *
 * // deleting entries during iteration:
 * for (TIntIntIterator it = map.iterator();
 *      it.hasNext();) {
 *   it.forward();
 *   if (satisfiesCondition(it.key()) {
 *     it.remove();
 *   }
 * }
 * 
* *
 * // faster iteration by avoiding hasNext():
 * TIntIntIterator iterator = map.iterator();
 * for (int i = map.size(); i-- > 0;) {    
 *   iterator.advance();     
 *   doSomethingWithKeyAndValue(iterator.key(), iterator.value());
 * }   
 * 
* * @author Eric D. Friedman * @version $Id: TIntIntIterator.java,v 1.1 2002/09/22 21:53:41 ericdf Exp $ */ public class TIntIntIterator extends TPrimitiveIterator { /** the collection being iterated over */ private final TIntIntHashMap _map; /** * Creates an iterator over the specified map */ public TIntIntIterator(TIntIntHashMap map) { super(map); this._map = map; } /** * Moves the iterator forward to the next entry in the underlying map. * * @exception NoSuchElementException if the iterator is already exhausted */ public void advance() { moveToNextIndex(); } /** * Provides access to the key of the mapping at the iterator's position. * Note that you must advance() the iterator at least once * before invoking this method. * * @return the key of the entry at the iterator's current position. */ public int key() { return _map._set[_index]; } /** * Provides access to the value of the mapping at the iterator's position. * Note that you must advance() the iterator at least once * before invoking this method. * * @return the value of the entry at the iterator's current position. */ public int value() { return _map._values[_index]; } /** * Replace the value of the mapping at the iterator's position with the * specified value. Note that you must advance() the iterator at * least once before invoking this method. * * @param val the value to set in the current entry * @return the old value of the entry. */ public int setValue(int val) { int old = value(); _map._values[_index] = val; return old; } }// TIntIntIterator

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