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/*******************************************************************************
* Copyright (c) 2009, 2018 Cloudsmith Inc. and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Cloudsmith Inc. - initial API and implementation
*******************************************************************************/
package org.eclipse.equinox.internal.p2.metadata.expression;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import org.eclipse.equinox.p2.metadata.index.IIndexProvider;
/**
* The immutable context used when evaluating an expression.
*/
public final class Everything<T> extends MatchIteratorFilter<T> implements IRepeatableIterator<T> {
private boolean atStart = true;
private final Class<? extends T> elementClass;
public Everything(Class<? extends T> elementClass, Collection<T> collection) {
super(RepeatableIterator.create(collection == null ? Collections.emptyList() : collection));
this.elementClass = elementClass;
}
public Everything(Class<? extends T> elementClass, Iterator<? extends T> iterator, Expression expression) {
this(elementClass, iterator, needsRepeadedAccessToEverything(expression));
}
public Everything(Class<? extends T> elementClass, IIndexProvider<? extends T> indexProvider) {
super(RepeatableIterator.create(indexProvider));
this.elementClass = elementClass;
}
Everything(Class<? extends T> elementClass, Iterator<? extends T> iterator, boolean needsRepeat) {
super(needsRepeat ? RepeatableIterator.create(iterator) : iterator);
this.elementClass = elementClass;
}
@Override
public IRepeatableIterator<T> getCopy() {
Iterator<? extends T> iterator = getInnerIterator();
if (iterator instanceof IRepeatableIterator<?>)
return new Everything<>(elementClass, ((IRepeatableIterator<? extends T>) iterator).getCopy(), false);
if (atStart)
return this;
throw new UnsupportedOperationException();
}
@Override
public T next() {
atStart = false;
return super.next();
}
public Class<? extends T> getElementClass() {
return elementClass;
}
@Override
public Object getIteratorProvider() {
Iterator<? extends T> iterator = getInnerIterator();
if (iterator instanceof IRepeatableIterator<?>)
return ((IRepeatableIterator<?>) iterator).getIteratorProvider();
return this;
}
@Override
protected boolean isMatch(T val) {
return elementClass.isInstance(val);
}
/**
* Checks if the expression will make repeated requests for the 'everything' iterator.
* @return <code>true</code> if repeated requests will be made, <code>false</code> if not.
*/
private static boolean needsRepeadedAccessToEverything(Expression expression) {
return expression.countAccessToEverything() > 1;
}
}
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