/////////////////////////////////////////////////////////////////////////////// // 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; import java.util.ConcurrentModificationException; /** * Iterator for maps of type Object and double. * *
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 (TObjectDoubleIterator it = map.iterator(); * it.hasNext();) { * it.forward(); * if (satisfiesCondition(it.key()) { * doSomethingWithValue(it.value()); * } * } ** *
* // modifying values in-place through iteration: * for (TObjectDoubleIterator it = map.iterator(); * it.hasNext();) { * it.forward(); * if (satisfiesCondition(it.key()) { * it.setValue(newValueForKey(it.key())); * } * } ** *
* // deleting entries during iteration: * for (TObjectDoubleIterator it = map.iterator(); * it.hasNext();) { * it.forward(); * if (satisfiesCondition(it.key()) { * it.remove(); * } * } ** *
* // faster iteration by avoiding hasNext(): * TObjectDoubleIterator iterator = map.iterator(); * for (int i = map.size(); i-- > 0;) { * iterator.advance(); * doSomethingWithKeyAndValue(iterator.key(), iterator.value()); * } ** * @author Eric D. Friedman * @version $Id: TObjectDoubleIterator.java,v 1.1 2002/09/22 21:53:42 ericdf Exp $ */ public class TObjectDoubleIterator extends TIterator { private final TObjectDoubleHashMap _map; public TObjectDoubleIterator(TObjectDoubleHashMap 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 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 double 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 double setValue(double val) {
double old = value();
_map._values[_index] = val;
return old;
}
}// TObjectDoubleIterator