Package io.trino.sql.tree

Class LabelDereference

java.lang.Object
io.trino.sql.tree.Node
io.trino.sql.tree.Expression
io.trino.sql.tree.LabelDereference
public class LabelDereference extends Expression
A temporary IR representation of a label-prefixed column reference in the context of row pattern recognition.

It is created from a DereferenceExpression when the MEASURES or DEFINE expressions are rewritten using the TranslationMap: A.price -> DereferenceExpression("A", "price") -> LabelDereference("A", price_symbol). Next, the LabelDereference is processed by the LogicalIndexExtractor, and it is removed from the expression.

LabelDereference is a synthetic AST node. It had to be introduced in order to carry the rewritten symbol (`price_symbol` in the example). The DereferenceExpression cannot be used for that purpose, because it only contains identifiers, and a Symbol cannot be safely converted to an Identifier.