cloud-fan commented on code in PR #39747:
URL: https://github.com/apache/spark/pull/39747#discussion_r1089961244
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala:
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@@ -3039,3 +3039,100 @@ case class SplitPart (
partNum = newChildren.apply(2))
}
}
+
+/**
+ * Function to check if a given number string is a valid Luhn number. Returns
true, if the number
+ * string is a valid Luhn number, false otherwise.
+ */
+@ExpressionDescription(
+ usage = """
+ _FUNC_(str ) - Checks that a string of digits is valid according to the
Luhn algorithm.
+ This checksum function is widely applied on credit card numbers and
government identification
+ numbers to distinguish valid numbers from mistyped, incorrect numbers.
+ """,
+ examples = """
+ Examples:
+ > SELECT _FUNC_('8112189876');
+ true
+ > SELECT _FUNC_('79927398713');
+ true
+ > SELECT _FUNC_('79927398714');
+ false
+ """,
+ since = "3.5.0",
+ group = "string_funcs")
+case class Luhncheck(child: Expression) extends UnaryExpression with
ExpectsInputTypes {
+
+ override def nullable: Boolean = false
+
+ override protected def withNewChildInternal(newChild: Expression): Luhncheck
=
+ copy(child = newChild)
+
+ override def inputTypes: Seq[AbstractDataType] = Seq(StringType)
+
+ override def dataType: DataType = BooleanType
+
+ /**
+ * Default behavior of evaluation according to the default nullability of
UnaryExpression. If
+ * subclass of UnaryExpression override nullable, probably should also
override this.
+ */
+ override def eval(input: InternalRow): Any =
Luhncheck.isLuhnNumber(child.eval(input))
+
+ /**
+ * Returns Java source code that can be compiled to evaluate this
expression. The default
+ * behavior is to call the eval method of the expression. Concrete
expression implementations
+ * should override this to do actual code generation.
+ *
+ * @param ctx
+ * a [[CodegenContext]]
+ * @param ev
+ * an [[ExprCode]] with unique terms.
+ * @return
+ * an [[ExprCode]] containing the Java source code to generate the given
expression
+ */
+ override protected def doGenCode(ctx: CodegenContext, ev: ExprCode):
ExprCode = {
+ defineCodeGen(
+ ctx,
+ ev,
+ c => {
+
s"""org.apache.spark.sql.catalyst.expressions.Luhncheck.isLuhnNumber($c)"""
+ })
+ }
+}
+
+object Luhncheck {
Review Comment:
`AesDecrypt` is a good example. We can also move the code to
`ExpressionImplUtils`
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