io.datarouter.scanner.SortingScanner Maven / Gradle / Ivy

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/**
 * Copyright © 2009 HotPads ([email protected])
 *
 * 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 io.datarouter.scanner;

import java.util.Comparator;
import java.util.List;

public class SortingScanner extends BaseLinkedScanner{

	private final Comparator comparator;

	private boolean consumedInput;
	private Scanner sortedScanner;

	public SortingScanner(Scanner input, Comparator comparator){
		super(input);
		this.comparator = comparator;
		this.consumedInput = false;
	}

	@Override
	protected boolean advanceInternal(){
		if(!consumedInput){
			List items = input.list();
			items.sort(comparator);
			sortedScanner = Scanner.of(items);
			consumedInput = true;
		}
		if(sortedScanner.advance()){
			current = sortedScanner.current();
			return true;
		}
		return false;
	}

}