/*
* Copyright 2011 the original author or authors.
*
* 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.gradle.api.internal.collections;
import org.gradle.api.internal.WithEstimatedSize;
import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
public class FilteredCollection<T, S extends T> implements Collection<S>, WithEstimatedSize {
protected final Collection<T> collection;
protected final CollectionFilter<S> filter;
public FilteredCollection(Collection<T> collection, CollectionFilter<S> filter) {
this.collection = collection;
this.filter = filter;
}
public boolean add(S o) {
throw new UnsupportedOperationException(String.format("Cannot add '%s' to '%s' as it is a filtered collection", o, this));
}
public boolean addAll(Collection<? extends S> c) {
throw new UnsupportedOperationException(String.format("Cannot add all from '%s' to '%s' as it is a filtered collection", c, this));
}
public void clear() {
throw new UnsupportedOperationException(String.format("Cannot clear '%s' as it is a filtered collection", this));
}
protected boolean accept(Object o) {
return filter.filter(o) != null;
}
public boolean contains(Object o) {
return collection.contains(o) && accept(o);
}
public boolean containsAll(Collection<?> c) {
if (collection.containsAll(c)) {
for (Object o : c) {
if (!accept(o)) {
return false;
}
}
return true;
} else {
return false;
}
}
// boolean equals(Object o) {
//
// }
//
// int hashCode() {
//
// }
public boolean isEmpty() {
if (collection.isEmpty()) {
return true;
} else {
for (T o : collection) {
if (accept(o)) {
return false;
}
}
return true;
}
}
@Override
public int estimatedSize() {
return Estimates.estimateSizeOf(collection);
}
protected static class FilteringIterator<T, S extends T> implements Iterator<S>, WithEstimatedSize {
private final CollectionFilter<S> filter;
private final Iterator<T> iterator;
private final int estimatedSize;
private S next;
public FilteringIterator(Collection<T> collection, CollectionFilter<S> filter) {
this.iterator = collection.iterator();
this.filter = filter;
this.estimatedSize = Estimates.estimateSizeOf(collection);
this.next = findNext();
}
private S findNext() {
while (iterator.hasNext()) {
T potentialNext = iterator.next();
S filtered = filter.filter(potentialNext);
if (filtered != null) {
return filtered;
}
}
return null;
}
public boolean hasNext() {
return next != null;
}
public S next() {
if (next != null) {
S thisNext = next;
next = findNext();
return thisNext;
} else {
throw new NoSuchElementException();
}
}
public void remove() {
throw new UnsupportedOperationException("This iterator does not support removal");
}
@Override
public int estimatedSize() {
return estimatedSize;
}
}
public Iterator<S> iterator() {
return new FilteringIterator<T, S>(collection, filter);
}
public boolean remove(Object o) {
throw new UnsupportedOperationException(String.format("Cannot remove '%s' from '%s' as it is a filtered collection", o, this));
}
public boolean removeAll(Collection<?> c) {
throw new UnsupportedOperationException(String.format("Cannot remove all of '%s' from '%s' as it is a filtered collection", c, this));
}
public boolean retainAll(Collection<?> c) {
throw new UnsupportedOperationException(String.format("Cannot retain all of '%s' from '%s' as it is a filtered collection", c, this));
}
public int size() {
int i = 0;
for (T o : collection) {
if (accept(o)) {
++i;
}
}
return i;
}
public Object[] toArray() {
Object[] a = new Object[size()];
int i = 0;
for (T o : collection) {
if (accept(o)) {
a[i++] = o;
}
}
return a;
}
// TODO - a proper implementation of this
public <T> T[] toArray(T[] a) {
return (T[])toArray();
}
}