Short syntax for UNLIST with IN operator

doc/sql.extensions/README.unlist

@@ -67,5 +67,45 @@ Unacceptable behavior:
 	SELECT UNLIST FROM UNLIST('UNLIST,A,S,A') AS A;
 
 
+Short syntax for UNLIST with IN operator:
+	Since Firebird 6.0, UNLIST can be used directly with the IN operator without requiring a full subquery.
+	Instead of writing IN (SELECT * FROM UNLIST(...) AS U), you can now use the shorter syntax IN UNLIST(...).
+
+Syntax:
+	<in predicate> ::=
+		<value> [NOT] IN <table value function unlist short>
+
+	<table value function unlist short> ::=
+		UNLIST ( <input> [, <separator>] [, <data type conversion>] )
+
+Examples:
+
+A)
+	SELECT * FROM EMPLOYEE WHERE EMP_NO IN UNLIST('2,4,5,7,11');
+B)
+	SELECT * FROM EMPLOYEE WHERE JOB_COUNTRY IN UNLIST('France,Italy,England');
+C)
+	SELECT EMP_NO FROM EMPLOYEE	WHERE JOB_COUNTRY NOT IN UNLIST('USA');
+D)
+	SELECT * FROM EMPLOYEE WHERE DEPT_NO IN UNLIST('100:110:115:120', ':' RETURNING INT);
+E)
+	SET AUTOTERM;
+	RECREATE PROCEDURE GET_EMPLOYEES_BY_PHONE_EXT (PHONE VARCHAR(1000))
+	RETURNS (EMPLOYEE_NAME VARCHAR(100))
+	AS
+	BEGIN
+		FOR
+			SELECT FIRST_NAME FROM EMPLOYEE
+			WHERE PHONE_EXT IN UNLIST(:PHONE, ',' RETURNING INT)
+			INTO :EMPLOYEE_NAME
+		DO
+			SUSPEND;
+	END;
+
+	SELECT A.EMPLOYEE_NAME FROM GET_EMPLOYEES_BY_PHONE_EXT('2,3,7') AS A;
+
+Note:
+	The short syntax automatically provides the correlation name and column name,
+	so they cannot be specified explicitly when using this form.
 
 

src/dsql/parse.y

@@ -7756,8 +7756,36 @@ in_predicate
 				ComparativeBoolNode::DFLAG_ANSI_ANY, $4);
 			$$ = newNode<NotBoolNode>(node);
 		}
+	| value IN table_value_function_unlist_short
+		{
+			$$ = newNode<ComparativeBoolNode>(blr_eql, $1,
+				ComparativeBoolNode::DFLAG_ANSI_ANY, $3);
+		}
+	| value NOT IN table_value_function_unlist_short
+		{
+			const auto node = newNode<ComparativeBoolNode>(blr_eql, $1,
+				ComparativeBoolNode::DFLAG_ANSI_ANY, $4);
+			$$ = newNode<NotBoolNode>(node);
+		}
 	;
 
+%type <exprNode> table_value_function_unlist_short
+table_value_function_unlist_short
+: table_value_function_unlist
+	{
+		const auto unlistNode = nodeAs<UnlistFunctionSourceNode>($1);
+		unlistNode->alias = UnlistFunctionSourceNode::FUNC_NAME;
+
+		const auto rseNode = newNode<RseNode>();
+		rseNode->dsqlFlags |= RecordSourceNode::DFLAG_BODY_WRAPPER;
+		rseNode->dsqlFrom = newNode<RecSourceListNode>(unlistNode);
+
+		const auto selectNode = newNode<SelectExprNode>();
+		selectNode->querySpec = rseNode;
+
+		$$ = selectNode;
+	}
+
 %type <boolExprNode> exists_predicate
 exists_predicate
 	: EXISTS '(' select_expr ')'