[GitHub] [spark] cloud-fan commented on a change in pull request #27355: [SPARK-30625][SQL] Support `escape` as third parameter of the `like` function

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cloud-fan commented on a change in pull request #27355: [SPARK-30625][SQL] Support `escape` as third parameter of the `like` function
URL: https://github.com/apache/spark/pull/27355#discussion_r377436053
 
 

 ##########
 File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
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 @@ -107,46 +109,65 @@ abstract class StringRegexExpression extends BinaryExpression
       true
       > SELECT '%SystemDrive%/Users/John' _FUNC_ '/%SystemDrive/%//Users%' ESCAPE '/';
       true
+      > SELECT _FUNC_('_Apache Spark_', '__%Spark__', '_');
+      true
   """,
   note = """
     Use RLIKE to match with standard regular expressions.
   """,
   since = "1.0.0")
 // scalastyle:on line.contains.tab
-case class Like(left: Expression, right: Expression, escapeChar: Char)
-  extends StringRegexExpression {
+case class Like(str: Expression, pattern: Expression, escape: Expression)
+  extends TernaryExpression with StringRegexExpression {
 
-  def this(left: Expression, right: Expression) = this(left, right, '\\')
+  def this(str: Expression, pattern: Expression) = this(str, pattern, Literal("\\"))
+
+  override def inputTypes: Seq[DataType] = Seq(StringType, StringType, StringType)
+  override def children: Seq[Expression] = Seq(str, pattern, escape)
+
+  private lazy val escapeChar: Char = if (escape.foldable) {
+    escape.eval() match {
+      case s: UTF8String if s != null && s.numChars() == 1 => s.toString.charAt(0)
+      case s => throw new AnalysisException(
+        s"The 'escape' parameter must be a string literal of one char but it is $s.")
+    }
+  } else {
+    throw new AnalysisException("The 'escape' parameter must be a string literal.")
 
 Review comment:
   This kind of thing should be done in `checkInputDataTypes`.

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