From 782c16c6a154e760bf1608d633488538cd52da93 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 24 Aug 2000 03:29:15 +0000
Subject: SQL-language functions are now callable in ordinary fmgr contexts ...
 for example, an SQL function can be used in a functional index.  (I make no
 promises about speed, but it'll work ;-).)  Clean up and simplify handling of
 functions returning sets.

---
 src/backend/executor/execScan.c | 60 ++++++++++++++++++++---------------------
 1 file changed, 29 insertions(+), 31 deletions(-)

(limited to 'src/backend/executor/execScan.c')

diff --git a/src/backend/executor/execScan.c b/src/backend/executor/execScan.c
index a3f66d20cad..d000a4cf50a 100644
--- a/src/backend/executor/execScan.c
+++ b/src/backend/executor/execScan.c
@@ -12,7 +12,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/execScan.c,v 1.13 2000/07/17 03:04:53 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/execScan.c,v 1.14 2000/08/24 03:29:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -50,11 +50,10 @@ ExecScan(Scan *node,
 {
 	CommonScanState *scanstate;
 	EState	   *estate;
+	ExprContext *econtext;
 	List	   *qual;
-	bool		isDone;
+	ExprDoneCond isDone;
 	TupleTableSlot *resultSlot;
-	ExprContext *econtext;
-	ProjectionInfo *projInfo;
 
 	/* ----------------
 	 *	Fetch data from node
@@ -65,13 +64,6 @@ ExecScan(Scan *node,
 	econtext = scanstate->cstate.cs_ExprContext;
 	qual = node->plan.qual;
 
-	/* ----------------
-	 *	Reset per-tuple memory context to free any expression evaluation
-	 *	storage allocated in the previous tuple cycle.
-	 * ----------------
-	 */
-	ResetExprContext(econtext);
-
 	/* ----------------
 	 *	Check to see if we're still projecting out tuples from a previous
 	 *	scan tuple (because there is a function-returning-set in the
@@ -80,14 +72,21 @@ ExecScan(Scan *node,
 	 */
 	if (scanstate->cstate.cs_TupFromTlist)
 	{
-		projInfo = scanstate->cstate.cs_ProjInfo;
-		resultSlot = ExecProject(projInfo, &isDone);
-		if (!isDone)
+		resultSlot = ExecProject(scanstate->cstate.cs_ProjInfo, &isDone);
+		if (isDone == ExprMultipleResult)
 			return resultSlot;
 		/* Done with that source tuple... */
 		scanstate->cstate.cs_TupFromTlist = false;
 	}
 
+	/* ----------------
+	 *	Reset per-tuple memory context to free any expression evaluation
+	 *	storage allocated in the previous tuple cycle.  Note this can't
+	 *	happen until we're done projecting out tuples from a scan tuple.
+	 * ----------------
+	 */
+	ResetExprContext(econtext);
+
 	/*
 	 * get a tuple from the access method loop until we obtain a tuple
 	 * which passes the qualification.
@@ -121,8 +120,6 @@ ExecScan(Scan *node,
 
 		/* ----------------
 		 *	check that the current tuple satisfies the qual-clause
-		 *	if our qualification succeeds then we may
-		 *	leave the loop.
 		 *
 		 * check for non-nil qual here to avoid a function call to
 		 * ExecQual() when the qual is nil ... saves only a few cycles,
@@ -130,7 +127,22 @@ ExecScan(Scan *node,
 		 * ----------------
 		 */
 		if (!qual || ExecQual(qual, econtext, false))
-			break;
+		{
+			/* ----------------
+			 *	Found a satisfactory scan tuple.
+			 *
+			 *	Form a projection tuple, store it in the result tuple
+			 *	slot and return it --- unless we find we can project no
+			 *	tuples from this scan tuple, in which case continue scan.
+			 * ----------------
+			 */
+			resultSlot = ExecProject(scanstate->cstate.cs_ProjInfo, &isDone);
+			if (isDone != ExprEndResult)
+			{
+				scanstate->cstate.cs_TupFromTlist = (isDone == ExprMultipleResult);
+				return resultSlot;
+			}
+		}
 
 		/* ----------------
 		 *	Tuple fails qual, so free per-tuple memory and try again.
@@ -138,18 +150,4 @@ ExecScan(Scan *node,
 		 */
 		ResetExprContext(econtext);
 	}
-
-	/* ----------------
-	 *	Found a satisfactory scan tuple.
-	 *
-	 *	Form a projection tuple, store it in the result tuple
-	 *	slot and return it.
-	 * ----------------
-	 */
-	projInfo = scanstate->cstate.cs_ProjInfo;
-
-	resultSlot = ExecProject(projInfo, &isDone);
-	scanstate->cstate.cs_TupFromTlist = !isDone;
-
-	return resultSlot;
 }
-- 
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