| /* |
| * 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.lambda; |
| |
| import org.apache.tinkerpop.gremlin.process.traversal.Traverser; |
| import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalUtil; |
| import org.apache.tinkerpop.gremlin.structure.Element; |
| |
| import java.util.Map; |
| import java.util.Objects; |
| |
| /** |
| * More efficiently extracts a value from an {@link Element} or {@code Map} to avoid strategy application costs. Note |
| * that as of 3.4.5 this class is now poorly named as it was originally designed to work with {@link Element} only. |
| * In future 3.5.0 this class will likely be renamed but to ensure that we get this revised functionality for |
| * {@code Map} without introducing a breaking change this name will remain the same. |
| * |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| */ |
| public final class ElementValueTraversal<V> extends AbstractLambdaTraversal<Element, V> { |
| |
| private final String propertyKey; |
| private V value; |
| |
| public ElementValueTraversal(final String propertyKey) { |
| this.propertyKey = propertyKey; |
| } |
| |
| @Override |
| public V next() { |
| return this.value; |
| } |
| |
| @Override |
| public boolean hasNext() { |
| return true; |
| } |
| |
| @Override |
| public void addStart(final Traverser.Admin<Element> start) { |
| if (null == this.bypassTraversal) { |
| // playing a game of type erasure here.....technically we can process either Map or Element here in this |
| // case after 3.4.5. and obviously users get weird errors along those lines here anyway. will fix up the |
| // generics in 3.5.0 when we can take some breaking changes. seemed like this feature would make Gremlin |
| // a lot nicer and given the small footprint of the change this seemed like a good hack to take. |
| final Object o = start.get(); |
| if (o instanceof Element) |
| this.value = ((Element) o).value(propertyKey); |
| else if (o instanceof Map) |
| this.value = (V) ((Map) o).get(propertyKey); |
| else |
| throw new IllegalStateException(String.format( |
| "The by(\"%s\") modulator can only be applied to a traverser that is an Element or a Map - it is being applied to [%s] a %s class instead", |
| propertyKey, o, o.getClass().getSimpleName())); |
| } else { |
| this.value = TraversalUtil.apply(start, this.bypassTraversal); |
| } |
| } |
| |
| public String getPropertyKey() { |
| return this.propertyKey; |
| } |
| |
| @Override |
| public String toString() { |
| return "value(" + (null == this.bypassTraversal ? this.propertyKey : this.bypassTraversal) + ')'; |
| } |
| |
| @Override |
| public int hashCode() { |
| return super.hashCode() ^ this.propertyKey.hashCode(); |
| } |
| |
| @Override |
| public boolean equals(final Object other) { |
| return other instanceof ElementValueTraversal |
| && Objects.equals(((ElementValueTraversal) other).propertyKey, this.propertyKey); |
| } |
| } |