gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/util/DefaultTraversalStrategies.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.util;

import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategies;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy;
import org.apache.tinkerpop.gremlin.structure.util.StringFactory;

import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Optional;
import java.util.Set;

/**
 * @author Marko A. Rodriguez (http://markorodriguez.com)
 */
public class DefaultTraversalStrategies implements TraversalStrategies {

    protected Set<TraversalStrategy<?>> traversalStrategies = new LinkedHashSet<>();

    @Override
    @SuppressWarnings({"unchecked", "varargs"})
    public TraversalStrategies addStrategies(final TraversalStrategy<?>... strategies) {
        for (final TraversalStrategy<?> addStrategy : strategies) {
            this.traversalStrategies.remove(addStrategy);
        }
        Collections.addAll(this.traversalStrategies, strategies);
        this.traversalStrategies = TraversalStrategies.sortStrategies(this.traversalStrategies);
        return this;
    }

    @Override
    @SuppressWarnings({"unchecked", "varargs"})
    public TraversalStrategies removeStrategies(final Class<? extends TraversalStrategy>... strategyClasses) {
        boolean removed = false;
        for (final Class<? extends TraversalStrategy> strategyClass : strategyClasses) {
            final Optional<TraversalStrategy<?>> strategy = this.traversalStrategies.stream().filter(s -> s.getClass().equals(strategyClass)).findAny();
            if (strategy.isPresent()) {
                this.traversalStrategies.remove(strategy.get());
                removed = true;
            }
        }
        if (removed)
            this.traversalStrategies = TraversalStrategies.sortStrategies(this.traversalStrategies);
        return this;
    }

    @Override
    public List<TraversalStrategy<?>> toList() {
        return Collections.unmodifiableList(new ArrayList<>(this.traversalStrategies));
    }

    @Override
    public <T extends TraversalStrategy> Optional<T> getStrategy(final Class<T> traversalStrategyClass) {
        for (final TraversalStrategy<?> traversalStrategy : this.traversalStrategies) {
            if (traversalStrategyClass.isAssignableFrom(traversalStrategy.getClass()))
                return (Optional) Optional.of(traversalStrategy);
        }
        return Optional.empty();
    }
    /**
     * @deprecated As of release 3.3.10, not directly replaced as this mode of strategy application has not been
     * utilized since early days of 3.x
     */
    @Override
    @Deprecated
    public void applyStrategies(final Traversal.Admin<?, ?> traversal) {
        for (final TraversalStrategy<?> traversalStrategy : this.traversalStrategies) {
            traversalStrategy.apply(traversal);
        }
    }

    @Override
    public DefaultTraversalStrategies clone() {
        try {
            final DefaultTraversalStrategies clone = (DefaultTraversalStrategies) super.clone();
            clone.traversalStrategies = new LinkedHashSet<>(this.traversalStrategies.size());
            clone.traversalStrategies.addAll(this.traversalStrategies);
            return clone;
        } catch (final CloneNotSupportedException e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
    }

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