From 116d2bba7eeaf25c544bc187e3ad2a8677a9a22c Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 19 Jun 2001 22:39:12 +0000
Subject: 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.

---
 src/backend/executor/execQual.c | 138 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 137 insertions(+), 1 deletion(-)

(limited to 'src/backend/executor')

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);
 
 
 /*----------
@@ -1091,6 +1095,126 @@ ExecEvalCase(CaseExpr *caseExpr, ExprContext *econtext,
 	return (Datum) 0;
 }
 
+/* ----------------------------------------------------------------
+ *		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
  *
@@ -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",
-- 
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