gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/finalization/MatchAlgorithmStrategy.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.tinkerpop.gremlin.process.traversal.strategy.finalization;

import org.apache.commons.configuration.Configuration;
import org.apache.commons.configuration.MapConfiguration;
import org.apache.tinkerpop.gremlin.process.traversal.Step;
import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.MatchStep;
import org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy;
import org.apache.tinkerpop.gremlin.structure.util.StringFactory;

import java.util.Collections;

/**
 * @author Marko A. Rodriguez (http://markorodriguez.com)
 */
public final class MatchAlgorithmStrategy extends AbstractTraversalStrategy<TraversalStrategy.FinalizationStrategy> implements TraversalStrategy.FinalizationStrategy {

    private static final String MATCH_ALGORITHM = "matchAlgorithm";
    private Class<? extends MatchStep.MatchAlgorithm> matchAlgorithmClass;

    private MatchAlgorithmStrategy() {
        // for serialization
    }

    private MatchAlgorithmStrategy(final Class<? extends MatchStep.MatchAlgorithm> matchAlgorithmClass) {
        this.matchAlgorithmClass = matchAlgorithmClass;
    }

    @Override
    public void apply(final Traversal.Admin<?, ?> traversal) {
        for (final Step<?, ?> step : traversal.getSteps()) {
            if (step instanceof MatchStep) {
                ((MatchStep) step).setMatchAlgorithm(this.matchAlgorithmClass);
            }
        }
    }

    public static MatchAlgorithmStrategy create(final Configuration configuration) {
        try {
            return new MatchAlgorithmStrategy((Class) Class.forName(configuration.getString(MATCH_ALGORITHM)));
        } catch (final ClassNotFoundException e) {
            throw new IllegalArgumentException(e.getMessage(), e);
        }
    }

    @Override
    public Configuration getConfiguration() {
        return new MapConfiguration(Collections.singletonMap(MATCH_ALGORITHM, null != this.matchAlgorithmClass.getDeclaringClass() ?
                this.matchAlgorithmClass.getCanonicalName().replace("." + this.matchAlgorithmClass.getSimpleName(), "$" + this.matchAlgorithmClass.getSimpleName()) :
                this.matchAlgorithmClass.getCanonicalName()));
    }

    public static Builder build() {
        return new Builder();
    }

    @Override
    public String toString() {
        return StringFactory.traversalStrategyString(this);
    }

    public final static class Builder {

        private Class<? extends MatchStep.MatchAlgorithm> matchAlgorithmClass = MatchStep.CountMatchAlgorithm.class;

        private Builder() {
        }

        public Builder algorithm(final Class<? extends MatchStep.MatchAlgorithm> matchAlgorithmClass) {
            this.matchAlgorithmClass = matchAlgorithmClass;
            return this;
        }


        public MatchAlgorithmStrategy create() {
            return new MatchAlgorithmStrategy(this.matchAlgorithmClass);
        }
    }
}