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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 org.kuali.common.util.base.Precondition.checkNotNull;

import com.google.common.base.Function;

public final class NodeStringFunction implements Function, String> {

	public NodeStringFunction(Function function) {
		checkNotNull(function, "function");
		this.function = function;
	}

	/**
	 * Convert the element contained in each node to a string by calling it's toString() method
	 */
	public static  NodeStringFunction create() {
		return create(new ToStringFunction());
	}

	/**
	 * Convert the element contained in each node to a string by invoking {@code function} on it
	 */
	public static  NodeStringFunction create(Function function) {
		return new NodeStringFunction(function);
	}

	private final Function function;

	@Override
	public String apply(Node node) {
		checkNotNull(node, "node");
		checkNotNull(node.getElement(), "node.element");
		return function.apply(node.getElement());
	}

	private static class ToStringFunction implements Function {

		@Override
		public String apply(T element) {
			checkNotNull(element, "element");
			return element.toString();
		}
	}

}