Github user anabranch commented on a diff in the pull request: https://github.com/apache/spark/pull/16138#discussion_r91173386 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/datetimeExpressions.scala --- @@ -1047,6 +1047,53 @@ case class ToDate(child: Expression) extends UnaryExpression with ImplicitCastIn } /** + * Parses a column with a format to a timestamp. + */ +@ExpressionDescription( + usage = "_FUNC_(timestamp_str, fmt) - Parses the `timestamp` expression " + + "with the `fmt` expression.", + extended = """ + Examples: + > SELECT _FUNC_('2016-12-31', 'yyyy-MM-dd'); + 2016-12-31 + """) +case class ParseToDate(left: Expression, right: Expression, child: Expression) + extends RuntimeReplaceable with ImplicitCastInputTypes { + + def this(left: Expression, format: Expression) = { + this(left, format, ToDate(new ParseToTimestamp(left, format))) + } + + override def inputTypes: Seq[AbstractDataType] = Seq(StringType, StringType) + override def dataType: DataType = DateType + override def flatArguments: Iterator[Any] = Iterator(left, right) + override def sql: String = s"$prettyName(${left.sql}, ${right.sql})" +} + +/** + * Parses a column with a format to a timestamp. + */ +@ExpressionDescription( + usage = "_FUNC_(timestamp, fmt) - Parses the `timestamp` expression with the `fmt` expression.", + extended = """ + Examples: + > SELECT _FUNC_('2016-12-31', 'yyyy-MM-dd'); + 2016-12-31 00:00:00.0 + """) +case class ParseToTimestamp(left: Expression, right: Expression, child: Expression) + extends RuntimeReplaceable with ImplicitCastInputTypes { + + def this(left: Expression, format: Expression) = { + this(left, format, Cast(UnixTimestamp(left, format), TimestampType)) --- End diff -- Where i am stuck is, there seems to be some implicit converting between types somewhere that I don't understand. The two casts are not completely equivalent for reasons beyond my understanding.
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