/*******************************************************************************
* Copyright 2011 See AUTHORS file.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/
package com.glview.libgdx.graphics.utils;
import java.util.Iterator;
import com.glview.exception.GLViewRuntimeException;
/** Interface used to select items within an iterator against a predicate.
* @author Xoppa
*/
public interface Predicate<T> {
boolean evaluate(T arg0);
public class PredicateIterator<T> implements Iterator<T> {
public Iterator<T> iterator;
public Predicate<T> predicate;
public boolean end = false;
public boolean peeked = false;
public T next = null;
public PredicateIterator(final Iterable<T> iterable, final Predicate<T> predicate) {
this(iterable.iterator(), predicate);
}
public PredicateIterator(final Iterator<T> iterator, final Predicate<T> predicate) {
set(iterator, predicate);
}
public void set(final Iterable<T> iterable, final Predicate<T> predicate) {
set(iterable.iterator(), predicate);
}
public void set(final Iterator<T> iterator, final Predicate<T> predicate) {
this.iterator = iterator;
this.predicate = predicate;
end = peeked = false;
next = null;
}
@Override
public boolean hasNext() {
if (end) return false;
if (next != null) return true;
peeked = true;
while(iterator.hasNext()) {
final T n = iterator.next();
if (predicate.evaluate(n)) {
next = n;
return true;
}
}
end = true;
return false;
}
@Override
public T next() {
if (next == null && !hasNext())
return null;
final T result = next;
next = null;
peeked = false;
return result;
}
@Override
public void remove() {
if (peeked)
throw new GLViewRuntimeException("Cannot remove between a call to hasNext() and next().");
iterator.remove();
}
}
public static class PredicateIterable<T> implements Iterable<T> {
public Iterable<T> iterable;
public Predicate<T> predicate;
public PredicateIterator<T> iterator = null;
public PredicateIterable(Iterable<T> iterable, Predicate<T> predicate) {
set(iterable, predicate);
}
public void set(Iterable<T> iterable, Predicate<T> predicate) {
this.iterable = iterable;
this.predicate = predicate;
}
/** Returns an iterator. Note that the same iterator instance is returned each time this method is called.
* Use the {@link Predicate.PredicateIterator} constructor for nested or multithreaded iteration. */
@Override
public Iterator<T> iterator() {
if (iterator == null)
iterator = new PredicateIterator<T>(iterable.iterator(), predicate);
else
iterator.set(iterable.iterator(), predicate);
return iterator;
}
}
}