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, 137 insertions, 1 deletions

diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index 84aa271629b..fb950fdfd14 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.86 2001/04/19 04:29:02 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.87 2001/06/19 22:39:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -62,6 +62,10 @@ static Datum ExecEvalAnd(Expr *andExpr, ExprContext *econtext, bool *isNull);
 static Datum ExecEvalOr(Expr *orExpr, ExprContext *econtext, bool *isNull);
 static Datum ExecEvalCase(CaseExpr *caseExpr, ExprContext *econtext,
 			 bool *isNull, ExprDoneCond *isDone);
+static Datum ExecEvalNullTest(NullTest *ntest, ExprContext *econtext,
+			 bool *isNull, ExprDoneCond *isDone);
+static Datum ExecEvalBooleanTest(BooleanTest *btest, ExprContext *econtext,
+			 bool *isNull, ExprDoneCond *isDone);
 
 
 /*----------
@@ -1092,6 +1096,126 @@ ExecEvalCase(CaseExpr *caseExpr, ExprContext *econtext,
 }
 
 /* ----------------------------------------------------------------
+ *		ExecEvalNullTest
+ *
+ *		Evaluate a NullTest node.
+ * ----------------------------------------------------------------
+ */
+static Datum
+ExecEvalNullTest(NullTest *ntest,
+				 ExprContext *econtext,
+				 bool *isNull,
+				 ExprDoneCond *isDone)
+{
+	Datum		result;
+
+	result = ExecEvalExpr(ntest->arg, econtext, isNull, isDone);
+	switch (ntest->nulltesttype)
+    {
+        case IS_NULL:
+            if (*isNull)
+            {
+                *isNull = false;
+                return BoolGetDatum(true);
+            }
+            else
+                return BoolGetDatum(false);
+        case IS_NOT_NULL:
+            if (*isNull)
+            {
+                *isNull = false;
+                return BoolGetDatum(false);
+            }
+            else
+                return BoolGetDatum(true);
+        default:
+            elog(ERROR, "ExecEvalNullTest: unexpected nulltesttype %d",
+                 (int) ntest->nulltesttype);
+            return (Datum) 0;  /* keep compiler quiet */
+    }
+}
+
+/* ----------------------------------------------------------------
+ *		ExecEvalBooleanTest
+ *
+ *		Evaluate a BooleanTest node.
+ * ----------------------------------------------------------------
+ */
+static Datum
+ExecEvalBooleanTest(BooleanTest *btest,
+					ExprContext *econtext,
+					bool *isNull,
+					ExprDoneCond *isDone)
+{
+	Datum		result;
+
+	result = ExecEvalExpr(btest->arg, econtext, isNull, isDone);
+	switch (btest->booltesttype)
+    {
+        case IS_TRUE:
+            if (*isNull)
+            {
+                *isNull = false;
+                return BoolGetDatum(false);
+            }
+            else if (DatumGetBool(result))
+                return BoolGetDatum(true);
+			else
+                return BoolGetDatum(false);
+        case IS_NOT_TRUE:
+            if (*isNull)
+            {
+                *isNull = false;
+                return BoolGetDatum(true);
+            }
+            else if (DatumGetBool(result))
+                return BoolGetDatum(false);
+			else
+                return BoolGetDatum(true);
+        case IS_FALSE:
+            if (*isNull)
+            {
+                *isNull = false;
+                return BoolGetDatum(false);
+            }
+            else if (DatumGetBool(result))
+                return BoolGetDatum(false);
+			else
+                return BoolGetDatum(true);
+        case IS_NOT_FALSE:
+            if (*isNull)
+            {
+                *isNull = false;
+                return BoolGetDatum(true);
+            }
+            else if (DatumGetBool(result))
+                return BoolGetDatum(true);
+			else
+                return BoolGetDatum(false);
+        case IS_UNKNOWN:
+            if (*isNull)
+            {
+                *isNull = false;
+                return BoolGetDatum(true);
+            }
+			else
+                return BoolGetDatum(false);
+        case IS_NOT_UNKNOWN:
+            if (*isNull)
+            {
+                *isNull = false;
+                return BoolGetDatum(false);
+            }
+			else
+                return BoolGetDatum(true);
+        default:
+            elog(ERROR, "ExecEvalBooleanTest: unexpected booltesttype %d",
+                 (int) btest->booltesttype);
+            return (Datum) 0;  /* keep compiler quiet */
+    }
+}
+
+/* ----------------------------------------------------------------
  *		ExecEvalFieldSelect
  *
  *		Evaluate a FieldSelect node.
@@ -1266,6 +1390,18 @@ ExecEvalExpr(Node *expression,
 									isNull,
 									isDone);
 			break;
+		case T_NullTest:
+			retDatum = ExecEvalNullTest((NullTest *) expression,
+									econtext,
+									isNull,
+									isDone);
+			break;
+		case T_BooleanTest:
+			retDatum = ExecEvalBooleanTest((BooleanTest *) expression,
+									econtext,
+									isNull,
+									isDone);
+			break;
 
 		default:
 			elog(ERROR, "ExecEvalExpr: unknown expression type %d",