| /* |
| * 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.decoration; |
| |
| import org.apache.tinkerpop.gremlin.process.traversal.Traversal; |
| import org.apache.tinkerpop.gremlin.process.traversal.TraversalSource; |
| import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.util.EmptyStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy; |
| |
| import java.util.function.BinaryOperator; |
| import java.util.function.Supplier; |
| import java.util.function.UnaryOperator; |
| |
| /** |
| * The {@code SackStrategy} is used internal to the {@code withSack()} steps of {@link TraversalSource} and is not |
| * typically constructed directly. |
| * |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| */ |
| public final class SackStrategy extends AbstractTraversalStrategy<TraversalStrategy.DecorationStrategy> implements TraversalStrategy.DecorationStrategy { |
| |
| private final Supplier initialValue; |
| private final UnaryOperator splitOperator; |
| private final BinaryOperator mergeOperator; |
| |
| private SackStrategy(final Supplier initialValue, final UnaryOperator splitOperator, final BinaryOperator mergeOperator) { |
| if (null == initialValue) |
| throw new IllegalArgumentException("The initial value of a sack can not be null"); |
| this.initialValue = initialValue; |
| this.splitOperator = splitOperator; |
| this.mergeOperator = mergeOperator; |
| } |
| |
| @Override |
| public void apply(final Traversal.Admin<?, ?> traversal) { |
| if (traversal.isRoot()) |
| traversal.getSideEffects().setSack(this.initialValue, this.splitOperator, this.mergeOperator); |
| } |
| |
| public static <A> Builder<A> build() { |
| return new Builder<>(); |
| } |
| |
| public final static class Builder<A> { |
| |
| private Supplier<A> initialValue; |
| private UnaryOperator<A> splitOperator = null; |
| private BinaryOperator<A> mergeOperator = null; |
| |
| private Builder() { |
| } |
| |
| public Builder initialValue(final Supplier<A> initialValue) { |
| this.initialValue = initialValue; |
| return this; |
| } |
| |
| public Builder splitOperator(final UnaryOperator<A> splitOperator) { |
| this.splitOperator = splitOperator; |
| return this; |
| } |
| |
| public Builder mergeOperator(final BinaryOperator<A> mergeOperator) { |
| this.mergeOperator = mergeOperator; |
| return this; |
| } |
| |
| public SackStrategy create() { |
| return new SackStrategy(this.initialValue, this.splitOperator, this.mergeOperator); |
| } |
| } |
| } |