org.gradoop.flink.representation.transactional.traversalcode.TraversalCode.java Source code

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Here is the source code for org.gradoop.flink.representation.transactional.traversalcode.TraversalCode.java

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/**
 * Copyright  2014 - 2018 Leipzig University (Database Research Group)
 *
 * 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 org.gradoop.flink.representation.transactional.traversalcode;

import com.google.common.collect.Lists;
import org.apache.commons.lang3.StringUtils;

import java.io.Serializable;
import java.util.Iterator;
import java.util.List;

/**
 * Represents a graph by the log of a depth first search.
 *
 * @param <C> vertex and edge value type
 */
public class TraversalCode<C extends Comparable<C>> implements Serializable, Comparable<TraversalCode<C>> {

    /**
     * Included edges.
     */
    private final List<Traversal<C>> traversals;

    /**
     * Default constructor.
     */
    public TraversalCode() {
        this.traversals = Lists.newArrayList();
    }

    /**
     * Constructor.
     *
     * @param traversal initial traversals
     */
    public TraversalCode(Traversal<C> traversal) {
        this.traversals = Lists.newArrayListWithExpectedSize(1);
        this.traversals.add(traversal);
    }

    /**
     * Constructor.
     *
     * @param parent parent DFS-code
     */
    public TraversalCode(TraversalCode<C> parent) {
        this.traversals = Lists.newArrayList(parent.getTraversals());
    }

    public List<Traversal<C>> getTraversals() {
        return traversals;
    }

    @Override
    public String toString() {
        return StringUtils.join(traversals, ',');
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        TraversalCode code = (TraversalCode) o;

        return traversals.equals(code.traversals);
    }

    @Override
    public int hashCode() {
        return traversals.hashCode();
    }

    @Override
    public int compareTo(TraversalCode<C> that) {

        int comparison;

        boolean thisIsRoot = this.getTraversals().isEmpty();
        boolean thatIsRoot = that.getTraversals().isEmpty();

        if (thisIsRoot && !thatIsRoot) {
            comparison = -1;

        } else if (thatIsRoot && !thisIsRoot) {
            comparison = 1;

        } else {
            comparison = 0;

            Iterator<Traversal<C>> thisIterator = this.getTraversals().iterator();
            Iterator<Traversal<C>> thatIterator = that.getTraversals().iterator();

            // if two DFS-Codes share initial traversals,
            // the first different traversal will decide about comparison
            while (comparison == 0 && thisIterator.hasNext() && thatIterator.hasNext()) {
                comparison = thisIterator.next().compareTo(thatIterator.next());
            }

            // DFS-Codes are equal or one is parent of other
            if (comparison == 0) {

                // this is child, cause it has further traversals
                if (thisIterator.hasNext()) {
                    comparison = 1;

                    // that is child, cause it has further traversals
                } else if (thatIterator.hasNext()) {
                    comparison = -1;

                }
            }
        }

        return comparison;
    }
}