org.polarsys.reqcycle.utils.collect.collectors.WidthCollector.java Source code

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Here is the source code for org.polarsys.reqcycle.utils.collect.collectors.WidthCollector.java

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/*******************************************************************************
 *  Copyright (c) 2013 AtoS
 *  All rights reserved. This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License v1.0
 *  which accompanies this distribution, and is available at
 *  http://www.eclipse.org/legal/epl-v10.html *
 *  Contributors:
 *    Olivier Melois (AtoS) - initial API and implementation and/or initial documentation
 *   
 *******************************************************************************/
package org.polarsys.reqcycle.utils.collect.collectors;

import java.util.Collections;

import org.polarsys.reqcycle.utils.collect.Picker;
import org.polarsys.reqcycle.utils.collect.ResultHandler;
import org.polarsys.reqcycle.utils.collect.exceptions.CannotHandleException;
import org.polarsys.reqcycle.utils.collect.exceptions.CollectionAbortedException;

import com.google.common.collect.Iterables;

public class WidthCollector<T> extends AbstractCollector<T> {

    protected Iterable<T> startingElements;

    public WidthCollector(T startingElement, Iterable<? extends Picker<T>> pickers) {
        super(startingElement, pickers);
    }

    public WidthCollector(Iterable<T> startingElements, Iterable<? extends Picker<T>> pickers) {
        super(null, pickers);
        this.startingElements = startingElements;
    }

    public void collect(ResultHandler<T> handler) throws CollectionAbortedException {
        if (start != null && startingElements == null) {
            collectWidthWise(handler, start);
        }
        if (start == null && startingElements != null) {
            collectWidthWise(handler, startingElements);
        }
    }

    /**
     * Width wise collection.
     * 
     * @param handler
     *            the handler that processes each element.
     * @param element
     *            : the element from which the collection is performed.
     * @throws CollectionAbortedException
     */
    protected void collectWidthWise(ResultHandler<T> handler, T element) throws CollectionAbortedException {
        Iterable<T> singleton = Collections.singletonList(element);
        collectWidthWise(handler, singleton);
    }

    /**
     * Width wise collection.
     * 
     * @param handler
     *            the handler that processes each element.
     * @param element
     *            : the current layer from which the collection is performed.
     * @throws CollectionAbortedException
     */
    protected void collectWidthWise(ResultHandler<T> handler, Iterable<T> currentLayer)
            throws CollectionAbortedException {
        Iterable<T> nextLayer = Collections.emptyList();
        while (currentLayer != null && !Iterables.isEmpty(currentLayer)) {
            for (T currentElement : currentLayer) {
                try {
                    handler.handleResult(currentElement);
                    // Building the next layer.
                    for (Picker<T> picker : this.getPickers()) {
                        Iterable<T> nexts = picker.getNexts(currentElement); // getting children.
                        if (nexts != null) {
                            nextLayer = Iterables.concat(nextLayer, nexts);
                        }
                    }
                } catch (CannotHandleException e) {
                    // do nothing
                } catch (Exception e) {
                    throw new CollectionAbortedException(e);
                }
            }
            // The current layer has been processed. Going through the next one.
            currentLayer = nextLayer;
            nextLayer = Collections.emptyList();
        }
    }
}