/*
* Copyright 2003-2015 JetBrains s.r.o.
*
* 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 org.jetbrains.mps.util;
import org.jetbrains.annotations.NotNull;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* Iterator that uses {@link org.jetbrains.mps.util.Condition} to filter out undesired elements.
* <p/>
* Other than matching elements by condition, features of original iterator are preserved.
* <p/>
* This class is identical to jetbrains.mps.util.ConditionalIterator, just lives under another package in another dependency unit.
* Since I can't move that class here without breaking existing code, and don't want to split 'kernel' module into 'true kernel' and
* 'implementation kernel', the class is copied here and original is deprecated.
*
* @author Artem Tikhomirov
*/
public final class FilterIterator<T> implements Iterator<T> {
private final Iterator<? extends T> myIterator;
private final Condition<T> myCondition;
private T myNext;
public FilterIterator(@NotNull Iterator<? extends T> iterator, @NotNull Condition<T> condition) {
myIterator = iterator;
myCondition = condition;
myNext = nextInternal();
}
@Override
public boolean hasNext() {
return myNext != null;
}
@Override
public T next() {
if (myNext == null) {
throw new NoSuchElementException();
}
T result = myNext;
myNext = nextInternal();
return result;
}
@Override
public void remove() {
myIterator.remove();
}
private T nextInternal() {
T next;
while (myIterator.hasNext()) {
next = myIterator.next();
if (myCondition.met(next)) {
return next;
}
}
return null;
}
}