io.datarouter.scanner.RetainingScanner 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.LinkedList;

public class RetainingScanner extends BaseLinkedScanner>{

	private final LinkedList retainingList;

	public RetainingScanner(Scanner input, int retaining){
		super(input);
		retainingList = new LinkedList<>();
		for(int i = 0; i < retaining + 1; ++i){
			retainingList.add(null);
		}
	}

	@Override
	public boolean advanceInternal(){
		if(input.advance()){
			retainingList.removeLast();
			retainingList.offerFirst(input.current());
			current = new RetainingGroup<>(retainingList);
			return true;
		}
		return false;
	}

}