Copyright (c) 2000, 2009 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.core;

import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IOpenable;
import org.eclipse.jdt.core.JavaModelException;

An LRU cache of JavaElements.
/**
 * An LRU cache of <code>JavaElements</code>.
 */
public class ElementCache<K extends IJavaElement & IOpenable> extends OverflowingLRUCache<K, JavaElementInfo> {

	IJavaElement spaceLimitParent = null;

Constructs a new element cache of the given size.
/**
 * Constructs a new element cache of the given size.
 */
public ElementCache(int size) {
	super(size);
}
Constructs a new element cache of the given size.
/**
 * Constructs a new element cache of the given size.
 */
public ElementCache(int size, int overflow) {
	super(size, overflow);
}
Returns true if the element is successfully closed and
removed from the cache, otherwise false.
NOTE: this triggers an external removal of this element
by closing the element.
/**
 * Returns true if the element is successfully closed and
 * removed from the cache, otherwise false.
 *
 * <p>NOTE: this triggers an external removal of this element
 * by closing the element.
 */
@Override
protected boolean close(LRUCacheEntry<K, JavaElementInfo> entry) {
	if(!(entry.key instanceof Openable)) {
		return false;
	}
	Openable element = (Openable) entry.key;
	try {
		if (!element.canBeRemovedFromCache()) {
			return false;
		} else {
			element.close();
			return true;
		}
	} catch (JavaModelException npe) {
		return false;
	}
}

/*
 * Ensures that there is enough room for adding the children of the given info.
 * If the space limit must be increased, record the parent that needed this space limit.
 */
protected void ensureSpaceLimit(JavaElementInfo info, IJavaElement parent) {
	// ensure the children can be put without closing other elements
	int childrenSize = info.getChildren().length;
	int spaceNeeded = 1 + (int)((1 + this.loadFactor) * (childrenSize + this.overflow));
	if (this.spaceLimit < spaceNeeded) {
		// parent is being opened with more children than the space limit
		shrink(); // remove overflow
		setSpaceLimit(spaceNeeded);
		this.spaceLimitParent = parent;
	}
}

/*
 * Returns a new instance of the receiver.
 */
@Override
protected ElementCache<K> newInstance(int size, int newOverflow) {
	return new ElementCache<>(size, newOverflow);
}

/*
 * If the given parent was the one that increased the space limit, reset
 * the space limit to the given default value.
 */
protected void resetSpaceLimit(int defaultLimit, IJavaElement parent) {
	if (parent.equals(this.spaceLimitParent)) {
		setSpaceLimit(defaultLimit);
		this.spaceLimitParent = null;
	}
}

}