xiazcy commented on code in PR #2232: URL: https://github.com/apache/tinkerpop/pull/2232#discussion_r1327587045
########## gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/SubstringStepTest.java: ########## @@ -0,0 +1,62 @@ +/* + * 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.step.map; + +import org.apache.tinkerpop.gremlin.process.traversal.Traversal; +import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.__; +import org.apache.tinkerpop.gremlin.process.traversal.step.StepTest; +import org.junit.Test; + +import java.util.Arrays; +import java.util.Collections; +import java.util.List; + +import static org.junit.Assert.assertArrayEquals; +import static org.junit.Assert.assertEquals; + +public class SubstringStepTest extends StepTest { + + @Override + protected List<Traversal> getTraversals() { + return Arrays.asList( + __.substring(1L), + __.substring(1L, 2L)); + } + + @Test + public void testReturnTypes() { + assertEquals("ello wor", __.__("hello world").substring(1L, 8L).next()); Review Comment: Changed to take `int` arguments so not applicable. ########## gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/SubstringStep.java: ########## @@ -0,0 +1,108 @@ +/* + * 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.step.map; + +import org.apache.tinkerpop.gremlin.process.traversal.Traversal; +import org.apache.tinkerpop.gremlin.process.traversal.Traverser; +import org.apache.tinkerpop.gremlin.process.traversal.step.TraversalParent; +import org.apache.tinkerpop.gremlin.process.traversal.traverser.TraverserRequirement; + +import java.util.Collections; +import java.util.Set; + +/** + * Reference implementation for substring step, a mid-traversal step which returns a substring of the incoming string + * traverser with a 0-based start index (inclusive) and length specified. If the start index is negative then it will + * begin at the specified index counted from the end of the string, or 0 if exceeding the string length. + * Length is optional, if it is not specific or if it exceeds the length of the string then all remaining characters will + * be returned. Length <= 0 will return the empty string. Null values are not processed and remain as null when returned. + * If the incoming traverser is a non-String value then an {@code IllegalArgumentException} will be thrown. + * + * @author David Bechberger (http://bechberger.com) + * @author Yang Xia (http://github.com/xiazcy) + */ +public final class SubstringStep<S> extends ScalarMapStep<S, String> { + + private final Long start; + private final Long length; + + public SubstringStep(final Traversal.Admin traversal, final Long startIndex, final Long length) { + super(traversal); + this.start = startIndex; + this.length = length; + } + + public SubstringStep(final Traversal.Admin traversal, final Long startIndex) { + this(traversal, startIndex, null); + } + + @Override + protected String map(final Traverser.Admin<S> traverser) { + final S item = traverser.get(); + // throws when incoming traverser isn't a string + if (null != item && !(item instanceof String)) { + throw new IllegalArgumentException( + String.format("The substring() step can only take string as argument, encountered %s", item.getClass())); + } + + // to preserve null items + final String strItem = (String) item; + + if (null == strItem) + return null; + + final int newStart = processStartIndex(strItem.length()); + if (null == this.length) + return strItem.substring(newStart); + + // length < 0 will return the empty string. + if (this.length <= 0) + return ""; + + // if length specified exceeds the string length it is assumed to be equal to the length, which returns all + // remaining characters in the string. + return strItem.substring(newStart, + Math.toIntExact(Math.min(this.length + newStart, strItem.length()))); + } + + @Override + public Set<TraverserRequirement> getRequirements() { + return Collections.singleton(TraverserRequirement.OBJECT); + } + + @Override + public int hashCode() { Review Comment: Updated -- This is an automated message from the Apache Git Service. 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