[GitHub] [druid] gianm commented on a change in pull request #9893: Add REGEXP_LIKE, fix bugs in REGEXP_EXTRACT.

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

gianm commented on a change in pull request #9893:
URL: https://github.com/apache/druid/pull/9893#discussion_r434745199



##########
File path: processing/src/main/java/org/apache/druid/query/expression/RegexpLikeExprMacro.java
##########
@@ -0,0 +1,101 @@
+/*
+ * 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.druid.query.expression;
+
+import org.apache.druid.common.config.NullHandling;
+import org.apache.druid.java.util.common.IAE;
+import org.apache.druid.java.util.common.StringUtils;
+import org.apache.druid.math.expr.Expr;
+import org.apache.druid.math.expr.ExprEval;
+import org.apache.druid.math.expr.ExprMacroTable;
+import org.apache.druid.math.expr.ExprType;
+
+import javax.annotation.Nonnull;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class RegexpLikeExprMacro implements ExprMacroTable.ExprMacro
+{
+  private static final String FN_NAME = "regexp_like";
+
+  @Override
+  public String name()
+  {
+    return FN_NAME;
+  }
+
+  @Override
+  public Expr apply(final List<Expr> args)
+  {
+    if (args.size() != 2) {
+      throw new IAE("Function[%s] must have 2 arguments", name());
+    }
+
+    final Expr arg = args.get(0);
+    final Expr patternExpr = args.get(1);
+
+    if (!ExprUtils.isStringLiteral(patternExpr)) {
+      throw new IAE("Function[%s] pattern must be a string literal", name());
+    }
+
+    // Precompile the pattern.
+    final Pattern pattern = Pattern.compile(
+        StringUtils.nullToEmptyNonDruidDataString((String) patternExpr.getLiteralValue())
+    );
+
+    class RegexpLikeExpr extends ExprMacroTable.BaseScalarUnivariateMacroFunctionExpr
+    {
+      private RegexpLikeExpr(Expr arg)
+      {
+        super(FN_NAME, arg);
+      }
+
+      @Nonnull
+      @Override
+      public ExprEval eval(final ObjectBinding bindings)
+      {
+        final String s = NullHandling.nullToEmptyIfNeeded(arg.eval(bindings).asString());
+
+        if (s == null) {
+          // True nulls do not match anything. Note: this branch only executes in SQL-compatible null handling mode.
+          return ExprEval.of(false, ExprType.LONG);
+        } else {
+          final Matcher matcher = pattern.matcher(NullHandling.nullToEmptyIfNeeded(s));

Review comment:
       Good catch, I removed it.




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