[GitHub] [pinot] Jackie-Jiang commented on a change in pull request #7114: Support REGEXP_EXTRACT

[GitBox <gi...@apache.org>]

Jackie-Jiang commented on a change in pull request #7114:
URL: https://github.com/apache/pinot/pull/7114#discussion_r707667853



##########
File path: pinot-core/src/main/java/org/apache/pinot/core/operator/transform/function/RegexpExtractTransformFunction.java
##########
@@ -0,0 +1,119 @@
+/**
+ * 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.pinot.core.operator.transform.function;
+
+import com.google.common.base.Preconditions;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import org.apache.pinot.core.operator.blocks.ProjectionBlock;
+import org.apache.pinot.core.operator.transform.TransformResultMetadata;
+import org.apache.pinot.core.plan.DocIdSetPlanNode;
+import org.apache.pinot.segment.spi.datasource.DataSource;
+
+
+/**
+ * The REGEXP_EXTRACT transform function takes maximum 4 arguments:
+ * {@code REGEXP_EXTRACT(`value`, `regexp`[, `pos`, `occurrence`])}
+ * <ul>
+ *   <li>value: a string used to match the regular expression.</li>
+ *   <li>regex: the regular expression.</li>
+ *   <li>pos: the beginning position for regex match (starts with index 1).</li>
+ *   <li>occurrence: the `occurrence`-th regex match to return.</li>
+ * </ul>
+ * Returns the substring in `value` that matches the `regexp`.
+ * <p>Returns NULL if there is no match.
+ * <p>If `pos` is specified, the search starts at this `pos` character in `value`,
+ * otherwise it starts at the beginning. `pos` starts with index 1 and cannot be 0.
+ * If `pos` is greater than the length of `value`, NULL is returned.
+ * <p>If `occurrence` is specified, the search returns a specific occurrence of
+ * the regexp in `value`, otherwise it returns the first match.
+ */
+public class RegexpExtractTransformFunction extends BaseTransformFunction {
+  public static final String FUNCTION_NAME = "REGEXP_EXTRACT";
+
+  private TransformFunction _valueFunction;
+  private Pattern _regexp;
+  private int _position;
+  private int _occurrence;
+  private String[] _stringOutputRegexMatches;
+  private TransformResultMetadata _resultMetadata;
+
+  @Override
+  public String getName() {
+    return FUNCTION_NAME;
+  }
+
+  @Override
+  public void init(List<TransformFunction> arguments, Map<String, DataSource> dataSourceMap) {
+    Preconditions.checkArgument(
+        arguments.size() >= 2 && arguments.size() <= 4,
+        "REGEXP_EXTRACT takes between 2 to 4 arguments. See usage: "
+            + "REGEXP_EXTRACT(`value`, `regexp`[, `pos`, `occurrence`]");
+    _valueFunction = arguments.get(0);
+
+    TransformFunction regexpFunction = arguments.get(1);
+    Preconditions.checkState(
+        regexpFunction instanceof LiteralTransformFunction,
+        "`regexp` must be a literal regex expression.");
+    _regexp = Pattern.compile(((LiteralTransformFunction) regexpFunction).getLiteral());
+
+    if (arguments.size() >= 3) {
+      TransformFunction positionFunction = arguments.get(2);
+      Preconditions.checkState(positionFunction instanceof LiteralTransformFunction
+              && Integer.parseInt(((LiteralTransformFunction) positionFunction).getLiteral()) > 0,
+          "`pos` must be a literal, positive number.");
+      _position = Integer.parseInt(((LiteralTransformFunction) positionFunction).getLiteral());
+    } else {
+      _position = 1;
+    }
+    if (arguments.size() == 4) {
+      TransformFunction occurrenceFunction = arguments.get(3);
+      Preconditions.checkState(occurrenceFunction instanceof LiteralTransformFunction
+              && Integer.parseInt(((LiteralTransformFunction) occurrenceFunction).getLiteral()) > 0,
+          "`pos` must be a literal, positive number.");
+      _occurrence = Integer.parseInt(((LiteralTransformFunction) occurrenceFunction).getLiteral());
+    } else {
+      _occurrence = 1;
+    }
+    _resultMetadata = STRING_SV_NO_DICTIONARY_METADATA;
+    _stringOutputRegexMatches = new String[DocIdSetPlanNode.MAX_DOC_PER_CALL];
+  }
+
+  @Override
+  public TransformResultMetadata getResultMetadata() {
+    return _resultMetadata;
+  }
+
+  @Override
+  public String[] transformToStringValuesSV(ProjectionBlock projectionBlock) {
+    int length = projectionBlock.getNumDocs();
+    String[] valuesSV = _valueFunction.transformToStringValuesSV(projectionBlock);
+    for (int i = 0; i < length; ++i) {
+      Matcher matcher = _regexp.matcher(valuesSV[i].substring(_position - 1));
+      if (matcher.find()) {
+        _stringOutputRegexMatches[i] = matcher.group(_occurrence - 1);
+      } else {
+        _stringOutputRegexMatches[i] = null;

Review comment:
       We cannot put `null` in the response. Need to pick a default null value, or make it configurable from the function argument

##########
File path: pinot-common/src/main/java/org/apache/pinot/common/function/scalar/StringFunctions.java
##########
@@ -179,6 +180,48 @@ public static String rtrim(String input) {
     return RTRIM.matcher(input).replaceAll("");
   }
 
+  /**
+   * @see Pattern#matches(String, CharSequence)
+   * @param value input value
+   * @param regexp regular expression
+   * @return the matched result.
+   */
+  @ScalarFunction
+  public static String regexpExtract(String value, String regexp) {
+    return regexpExtract(value, regexp, 1, 1);
+  }
+
+  /**
+   * Regular expression extract that accepts starting position as argument.
+   * @param value input value
+   * @param regexp regular expression
+   * @param pos starting position
+   * @return the matched result.
+   */
+  @ScalarFunction
+  public static String regexpExtract(String value, String regexp, int pos) {
+    return regexpExtract(value, regexp, pos, 1);
+  }
+
+  /**
+   * Regular expression extract that accepts starting position and i-th occurrence as argument.
+   * @param value input value
+   * @param regexp regular expression
+   * @param pos starting position
+   * @param occurrence the specified i-th occurrence to extract.
+   * @return the matched result.
+   */
+  @ScalarFunction
+  public static String regexpExtract(String value, String regexp, int pos, int occurrence) {
+    Pattern p = Pattern.compile(regexp);
+    Matcher matcher = p.matcher(value.substring(pos - 1));
+    if (matcher.find()) {
+      return matcher.group(occurrence - 1);
+    } else {
+      return null;

Review comment:
       Same here. Pinot doesn't support null as of now




-- 
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: commits-unsubscribe@pinot.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org



---------------------------------------------------------------------
To unsubscribe, e-mail: commits-unsubscribe@pinot.apache.org
For additional commands, e-mail: commits-help@pinot.apache.org