Add IS UNKNOWN, IS NOT UNKNOWN boolean tests, fix the existing boolean

tests to return the correct results per SQL9x when given NULL inputs.
Reimplement these tests as well as IS [NOT] NULL to have their own
expression node types, instead of depending on special functions.
From Joe Conway, with a little help from Tom Lane.

1 files changed, 43 insertions, 1 deletions

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 77ae4fb781a..6cf5b35d266 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.144 2001/06/09 23:21:54 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.145 2001/06/19 22:39:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1017,6 +1017,42 @@ _copyCaseWhen(CaseWhen *from)
 	return newnode;
 }
 
+/* ----------------
+ *		_copyNullTest
+ * ----------------
+ */
+static NullTest *
+_copyNullTest(NullTest *from)
+{
+	NullTest *newnode = makeNode(NullTest);
+
+	/*
+	 * copy remainder of node
+	 */
+	Node_Copy(from, newnode, arg);
+	newnode->nulltesttype = from->nulltesttype;
+
+	return newnode;
+}
+
+/* ----------------
+ *		_copyBooleanTest
+ * ----------------
+ */
+static BooleanTest *
+_copyBooleanTest(BooleanTest *from)
+{
+	BooleanTest *newnode = makeNode(BooleanTest);
+
+	/*
+	 * copy remainder of node
+	 */
+	Node_Copy(from, newnode, arg);
+	newnode->booltesttype = from->booltesttype;
+
+	return newnode;
+}
+
 static ArrayRef *
 _copyArrayRef(ArrayRef *from)
 {
@@ -2954,6 +2990,12 @@ copyObject(void *from)
 		case T_CaseWhen:
 			retval = _copyCaseWhen(from);
 			break;
+		case T_NullTest:
+			retval = _copyNullTest(from);
+			break;
+		case T_BooleanTest:
+			retval = _copyBooleanTest(from);
+			break;
 		case T_FkConstraint:
 			retval = _copyFkConstraint(from);
 			break;