/*
* Copyright (c) 2012, 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.oracle.truffle.dsl.processor.util;
import java.util.Iterator;
import java.util.NoSuchElementException;
public class Filterator<T> implements Iterator<T> {
private final Predicate<T> includePredicate;
private final Iterator<T> elements;
private boolean hasCached;
private T cached;
public Filterator(Iterator<T> elements, Predicate<T> includePredicate) {
this.elements = elements;
this.includePredicate = includePredicate;
}
public boolean hasNext() {
if (hasCached) {
return true;
}
nextValue();
return hasCached;
}
private void nextValue() {
while (!hasCached && elements.hasNext()) {
T element = elements.next();
if (includePredicate.evaluate(element)) {
cached = element;
hasCached = true;
}
}
}
public T next() {
T foundCached = getCached();
if (foundCached != null) {
return foundCached;
} else {
nextValue();
if (!hasCached) {
throw new NoSuchElementException();
}
return getCached();
}
}
private T getCached() {
if (hasCached) {
hasCached = false;
T value = cached;
cached = null;
return value;
}
return null;
}
@Override
public void remove() {
elements.remove();
}
}