gnu.trove.THashIterator Maven / Gradle / Ivy
///////////////////////////////////////////////////////////////////////////////
// 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;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* Implements all iterator functions for the hashed object set.
* Subclasses may override objectAtIndex to vary the object
* returned by calls to next() (e.g. for values, and Map.Entry
* objects).
*
* Note that iteration is fastest if you forego the calls to
* hasNext in favor of checking the size of the structure
* yourself and then call next() that many times:
*
*
* Iterator i = collection.iterator();
* for (int size = collection.size(); size-- > 0;) {
* Object o = i.next();
* }
*
*
* You may, of course, use the hasNext(), next() idiom too if
* you aren't in a performance critical spot.
*
*/
abstract class THashIterator extends TIterator implements Iterator {
private final TObjectHash _object_hash;
/**
* Create an instance of THashIterator over the values of the TObjectHash
*/
public THashIterator(TObjectHash hash) {
super(hash);
_object_hash = hash;
}
/**
* Moves the iterator to the next Object and returns it.
*
* @return an Object value
* @exception ConcurrentModificationException if the structure
* was changed using a method that isn't on this iterator.
* @exception NoSuchElementException if this is called on an
* exhausted iterator.
*/
public V next() {
moveToNextIndex();
return objectAtIndex(_index);
}
/**
* Returns the index of the next value in the data structure
* or a negative value if the iterator is exhausted.
*
* @return an int value
* @exception ConcurrentModificationException if the underlying
* collection's size has been modified since the iterator was
* created.
*/
protected final int nextIndex() {
if (_expectedSize != _hash.size()) {
throw new ConcurrentModificationException();
}
Object[] set = _object_hash._set;
int i = _index;
while (i-- > 0 && (set[i] == TObjectHash.FREE || set[i] == TObjectHash.REMOVED)) ;
return i;
}
/**
* Returns the object at the specified index. Subclasses should
* implement this to return the appropriate object for the given
* index.
*
* @param index the index of the value to return.
* @return an Object value
*/
abstract protected V objectAtIndex(int index);
} // THashIterator