dylanhz commented on code in PR #24972: URL: https://github.com/apache/flink/pull/24972#discussion_r1703604984
########## flink-table/flink-table-runtime/src/main/java/org/apache/flink/table/runtime/functions/scalar/SubstringIndexFunction.java: ########## @@ -0,0 +1,155 @@ +/* + * 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.flink.table.runtime.functions.scalar; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.table.data.StringData; +import org.apache.flink.table.data.binary.BinaryStringData; +import org.apache.flink.table.functions.BuiltInFunctionDefinitions; +import org.apache.flink.table.functions.SpecializedFunction; +import org.apache.flink.util.FlinkRuntimeException; + +import org.apache.commons.lang3.StringUtils; + +import javax.annotation.Nullable; + +import java.util.Arrays; + +/** Implementation of {@link BuiltInFunctionDefinitions#SUBSTRING_INDEX}. */ +@Internal +public class SubstringIndexFunction extends BuiltInScalarFunction { + public SubstringIndexFunction(SpecializedFunction.SpecializedContext context) { + super(BuiltInFunctionDefinitions.SUBSTRING_INDEX, context); + } + + public @Nullable StringData eval( + @Nullable StringData expr, @Nullable StringData delim, @Nullable Integer count) { + if (expr == null || delim == null || count == null) { + return null; + } + + if (count == 0) { + return BinaryStringData.EMPTY_UTF8; + } + String str = expr.toString(); + if (str.isEmpty()) { + return BinaryStringData.EMPTY_UTF8; + } + String delimiter = delim.toString(); + if (delimiter.isEmpty()) { + return BinaryStringData.EMPTY_UTF8; + } + + try { + if (count > 0) { + // get index of the count-th occurrences of delimiter + int idx = StringUtils.ordinalIndexOf(str, delimiter, count); + if (idx != StringUtils.INDEX_NOT_FOUND) { + return StringData.fromString(str.substring(0, idx)); + } + } else { + // get index of the last -count-th occurrences of delimiter + int idx = StringUtils.lastOrdinalIndexOf(str, delimiter, -count); + if (idx != StringUtils.INDEX_NOT_FOUND) { + return StringData.fromString(str.substring(idx + delimiter.length())); + } + } + } catch (Throwable t) { + throw new FlinkRuntimeException(t); + } + + // can not find enough delimiter + return expr; + } + + public @Nullable byte[] eval( + @Nullable byte[] expr, @Nullable byte[] delim, @Nullable Integer count) { + if (expr == null || delim == null || count == null) { + return null; + } + if (expr.length == 0 || delim.length == 0 || count == 0) { + return new byte[] {}; + } + + if (count > 0) { + int idx = -1; + while (count > 0) { + // get index of the next occurrence of delim + idx = find(expr, idx + 1, delim); + if (idx >= 0) { + --count; + } else { + // can not find enough delim + return expr; + } + } + if (idx == 0) { + return new byte[] {}; + } + return Arrays.copyOfRange(expr, 0, idx); + + } else { + int idx = expr.length - delim.length + 1; + while (count < 0) { + // get index of the previous occurrence of delim + idx = rfind(expr, idx - 1, delim); + if (idx >= 0) { + ++count; + } else { + // can not find enough delim + return expr; + } + } + if (idx + delim.length == expr.length) { + return new byte[] {}; + } + return Arrays.copyOfRange(expr, idx + delim.length, expr.length); + } + } + + private int find(byte[] str, int beginIdx, byte[] target) { + final int endIdx = str.length - target.length; Review Comment: BTW, I do find a bug in the next row, `beginIndex < endIndex` should be `beginIndex <= endIndex`. Corresponding test cases have been added. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
