cloud-fan commented on code in PR #45708:
URL: https://github.com/apache/spark/pull/45708#discussion_r1538615582
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/variant/variantExpressions.scala:
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@@ -63,3 +70,300 @@ case class ParseJson(child: Expression) extends
UnaryExpression
override protected def withNewChildInternal(newChild: Expression): ParseJson
=
copy(child = newChild)
}
+
+// A path segment in the `VariantGet` expression. It represents either an
object key access (when
+// `key` is not null) or an array index access (when `key` is null).
+case class PathSegment(key: String, index: Int)
+
+object VariantPathParser extends RegexParsers {
+ private def root: Parser[Char] = '$'
+
+ // Parse index segment like `[123]`.
+ private def index: Parser[PathSegment] =
+ for {
+ index <- '[' ~> "\\d+".r <~ ']'
+ } yield {
+ PathSegment(null, index.toInt)
+ }
+
+ // Parse key segment like `.name`, `['name']`, or `["name"]`.
+ private def key: Parser[PathSegment] =
+ for {
+ key <- '.' ~> "[^\\.\\[]+".r | "['" ~> "[^\\'\\?]+".r <~ "']" |
+ "[\"" ~> "[^\\\"\\?]+".r <~ "\"]"
+ } yield {
+ PathSegment(key, 0)
+ }
+
+ private val parser: Parser[List[PathSegment]] = phrase(root ~> rep(key |
index))
+
+ def parse(str: String): Option[Array[PathSegment]] = {
+ this.parseAll(parser, str) match {
+ case Success(result, _) => Some(result.toArray)
+ case _ => None
+ }
+ }
+}
+
+/**
+ * The implementation for `variant_get` and `try_variant_get` expressions.
Extracts a sub-variant
+ * value according to a path and cast it into a concrete data type.
+ * @param child The source variant value to extract from.
+ * @param path A literal path expression. It has the same format as the JSON
path.
+ * @param schema The target data type to cast into.
+ * @param failOnError Controls whether the expression should throw an
exception or return null if
+ * the cast fails.
+ * @param timeZoneId A string identifier of a time zone. It is required by
timestamp-related casts.
+ */
+case class VariantGet(
+ child: Expression,
+ path: Expression,
+ schema: DataType,
Review Comment:
```suggestion
targetType: DataType,
```
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