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Kuali Utilities
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/**
 * Copyright 2010-2014 The Kuali Foundation
 *
 * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
 *
 * 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.kuali.common.util.tree;

import static com.google.common.collect.Lists.newArrayList;
import static com.google.common.collect.Lists.reverse;
import static com.google.common.collect.Lists.transform;
import static org.kuali.common.util.base.Precondition.checkNotNull;

import java.util.List;

public abstract class AbstractNode implements Node {

	/**
	 * Return true if this is the root node (ie it has no parent)
	 */
	@Override
	public boolean isRoot() {
		return !getParent().isPresent();
	}

	/**
	 * Return true if this is a leaf node (ie it has no children)
	 */
	@Override
	public boolean isLeaf() {
		return getChildren().isEmpty();
	}

	/**
	 * Returns the number of levels above this node. The distance from the root to this node. If this node is the root, returns 0.
	 */
	@Override
	public int getLevel() {
		int level = 0;
		Node ancestor = this;
		while (ancestor.getParent().isPresent()) {
			ancestor = ancestor.getParent().get();
			level++;
		}
		return level;
	}

	/**
	 * Returns the path from the root, to get to this node. The last element in the path is this node.
	 */
	@Override
	public List> getPath() {
		Node ancestor = this;
		List> list = newArrayList();
		list.add(ancestor);
		while (ancestor.getParent().isPresent()) {
			ancestor = ancestor.getParent().get();
			list.add(ancestor);
		}
		return reverse(list);
	}

	/**
	 * Returns the node elements in the path from the root, to get to this node. The last entry is the element from this node
	 */
	@Override
	public List getElementPath() {
		return transform(getPath(), new NodeElementFunction());
	}

	/**
	 * Return true if this node is a child of parent
	 */
	@Override
	public boolean isChild(Node parent) {
		checkNotNull(parent, "parent");
		return parent.getChildren().contains(this);
	}

	/**
	 * Return true if this node is a parent of child
	 */
	@Override
	public boolean isParent(Node child) {
		checkNotNull(child, "child");
		return getChildren().contains(child);
	}

	/**
	 * Return true if this node descends from parent OR is parent
	 */
	@Override
	public boolean isAncestor(Node parent) {
		checkNotNull(parent, "parent");
		return getPath().contains(parent);
	}

}