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/*
* Copyright 2000-2014 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 com.intellij.util.containers;
import com.intellij.openapi.util.Condition;
import com.intellij.openapi.util.Conditions;
import org.jetbrains.annotations.NotNull;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* {@link #remove} throws {@link IllegalStateException} if called after {@link #hasNext}
* @author dsl
* @author dyoma
*/
public class FilteringIterator<Dom, E extends Dom> implements Iterator<E> {
private final Iterator<Dom> myBaseIterator;
private final Condition<? super Dom> myFilter;
private boolean myNextObtained = false;
private boolean myCurrentIsValid = false;
private Dom myCurrent;
private Boolean myCurrentPassedFilter = null;
public static final Condition NOT_NULL = new Condition() {
@Override
public boolean value(Object t) {
return t != null;
}
};
public FilteringIterator(@NotNull Iterator<Dom> baseIterator, @NotNull Condition<? super Dom> filter) {
myBaseIterator = baseIterator;
myFilter = filter;
}
private void obtainNext() {
if (myNextObtained) return;
boolean hasNext = myBaseIterator.hasNext();
setCurrent(hasNext ? myBaseIterator.next() : null);
myCurrentIsValid = hasNext;
myNextObtained = true;
}
@Override
public boolean hasNext() {
obtainNext();
if (!myCurrentIsValid) return false;
boolean value = isCurrentPassesFilter();
while (!value && myBaseIterator.hasNext()) {
Dom next = myBaseIterator.next();
setCurrent(next);
value = isCurrentPassesFilter();
}
return value;
}
private void setCurrent(Dom next) {
myCurrent = next;
myCurrentPassedFilter = null;
}
private boolean isCurrentPassesFilter() {
if (myCurrentPassedFilter != null) return myCurrentPassedFilter.booleanValue();
boolean passed = myFilter.value(myCurrent);
myCurrentPassedFilter = Boolean.valueOf(passed);
return passed;
}
@Override
public E next() {
if (!hasNext()) throw new NoSuchElementException();
E result = (E)myCurrent;
myNextObtained = false;
return result;
}
/**
* Works after call {@link #next} until call {@link #hasNext}
* @throws IllegalStateException if {@link #hasNext} called
*/
@Override
public void remove() {
if (myNextObtained) throw new IllegalStateException();
myBaseIterator.remove();
}
public static <T> Iterator<T> skipNulls(Iterator<T> iterator) {
return create(iterator, NOT_NULL);
}
public static <Dom, T extends Dom> Iterator<T> create(Iterator<Dom> iterator, Condition<? super Dom> condition) {
return new FilteringIterator<Dom, T>(iterator, condition);
}
public static <T> Condition<T> alwaysTrueCondition(Class<T> aClass) {
return Conditions.alwaysTrue();
}
public static <T> InstanceOf<T> instanceOf(final Class<T> aClass) {
return new InstanceOf<T>(aClass);
}
public static <T> Iterator<T> createInstanceOf(Iterator<?> iterator, Class<T> aClass) {
return create((Iterator<T>)iterator, instanceOf(aClass));
}
public static class InstanceOf<T> implements Condition<Object> {
private final Class<T> myInstancesClass;
public InstanceOf(Class<T> instancesClass) {
myInstancesClass = instancesClass;
}
@Override
public boolean value(Object object) {
return myInstancesClass.isInstance(object);
}
}
}
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