Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/7214#discussion_r33885110
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
---
@@ -298,3 +299,34 @@ case class StringLength(child: Expression) extends
UnaryExpression with ExpectsI
override def prettyName: String = "length"
}
+
+/**
+ * A function that return the Levenshtein distance between the two given
strings.
+ */
+case class Levenshtein(left: Expression, right: Expression) extends
BinaryExpression
+ with ExpectsInputTypes {
+
+ override def inputTypes: Seq[AbstractDataType] = Seq(StringType,
StringType)
+
+ override def eval(input: InternalRow): Any = {
+ val leftValue = left.eval(input)
+ if (leftValue == null) {
+ null
+ } else {
+ val rightValue = right.eval(input)
+ if(rightValue == null) {
+ null
+ } else {
+ StringUtils.getLevenshteinDistance(leftValue.toString,
rightValue.toString)
+ }
+ }
+ }
+
+ override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode):
String = {
+ val stringUtils = classOf[StringUtils].getName
+ nullSafeCodeGen(ctx, ev, (res, left, right) =>
+ s"$res = $stringUtils.getLevenshteinDistance($left.toString(),
$right.toString());")
+ }
+
+ override def dataType: DataType = IntegerType
--- End diff --
can you move this right after inputTypes?
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