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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 com.gemstone.gnu.trove;
import java.util.ConcurrentModificationException;
/**
* Iterator for maps of type Object and float.
*
* 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 (TObjectFloatIterator it = map.iterator();
* it.hasNext();) {
* it.forward();
* if (satisfiesCondition(it.key()) {
* doSomethingWithValue(it.value());
* }
* }
*
*
*
* // modifying values in-place through iteration:
* for (TObjectFloatIterator it = map.iterator();
* it.hasNext();) {
* it.forward();
* if (satisfiesCondition(it.key()) {
* it.setValue(newValueForKey(it.key()));
* }
* }
*
*
*
* // deleting entries during iteration:
* for (TObjectFloatIterator it = map.iterator();
* it.hasNext();) {
* it.forward();
* if (satisfiesCondition(it.key()) {
* it.remove();
* }
* }
*
*
*
* // faster iteration by avoiding hasNext():
* TObjectFloatIterator iterator = map.iterator();
* for (int i = map.size(); i-- > 0;) {
* iterator.advance();
* doSomethingWithKeyAndValue(iterator.key(), iterator.value());
* }
*
*
* @author Eric D. Friedman
* @version $Id: TObjectFloatIterator.java,v 1.1 2002/09/22 21:53:42 ericdf Exp $
*/
public class TObjectFloatIterator extends TIterator {
private final TObjectFloatHashMap _map;
public TObjectFloatIterator(TObjectFloatHashMap map) {
super(map);
this._map = map;
}
/**
* Returns the index of the next value in the data structure
* or a negative value if the iterator is exhausted.
*
* @return an int value
*/
protected final int nextIndex() {
if (_expectedSize != _hash.size()) {
throw new ConcurrentModificationException();
}
Object[] set = _map._set;
int i = _index;
while (i-- > 0 && (set[i] == null || set[i] == TObjectHash.REMOVED)) ;
return i;
}
/**
* Moves the iterator forward to the next entry in the underlying map.
*
* @exception java.util.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 Object 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 float 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 float setValue(float val) {
float old = value();
_map._values[_index] = val;
return old;
}
}// TObjectFloatIterator