From 51972a9d5d068dd34b24ff4923981ffb90e5cc2d Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 16 Feb 2003 02:30:39 +0000
Subject: COALESCE() and NULLIF() are now first-class expressions, not macros
 that turn into CASE expressions.  They evaluate their arguments at most once.
  Patch by Kris Jurka, review and (very light) editorializing by me.

---
 src/backend/nodes/readfuncs.c | 47 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

(limited to 'src/backend/nodes/readfuncs.c')

diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index f37856728b1..410d092c916 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.148 2003/02/09 06:56:27 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.149 2003/02/16 02:30:37 tgl Exp $
  *
  * NOTES
  *	  Path and Plan nodes do not have any readfuncs support, because we
@@ -606,6 +606,47 @@ _readCaseWhen(void)
 	READ_DONE();
 }
 
+/*
+ * _readCoalesceExpr
+ */
+static CoalesceExpr *
+_readCoalesceExpr(void)
+{
+	READ_LOCALS(CoalesceExpr);
+
+	READ_OID_FIELD(coalescetype);
+	READ_NODE_FIELD(args);
+
+	READ_DONE();
+}
+
+/*
+ * _readNullIfExpr
+ */
+static NullIfExpr *
+_readNullIfExpr(void)
+{
+	READ_LOCALS(NullIfExpr);
+
+	READ_OID_FIELD(opno);
+	READ_OID_FIELD(opfuncid);
+	/*
+	 * The opfuncid is stored in the textual format primarily for debugging
+	 * and documentation reasons.  We want to always read it as zero to force
+	 * it to be re-looked-up in the pg_operator entry.  This ensures that
+	 * stored rules don't have hidden dependencies on operators' functions.
+	 * (We don't currently support an ALTER OPERATOR command, but might
+	 * someday.)
+	 */
+	local_node->opfuncid = InvalidOid;
+
+	READ_OID_FIELD(opresulttype);
+	READ_BOOL_FIELD(opretset);
+	READ_NODE_FIELD(args);
+
+	READ_DONE();
+}
+
 /*
  * _readNullTest
  */
@@ -895,6 +936,10 @@ parseNodeString(void)
 		return_value = _readCaseExpr();
 	else if (MATCH("WHEN", 4))
 		return_value = _readCaseWhen();
+	else if (MATCH("COALESCE", 8))
+		return_value = _readCoalesceExpr();
+	else if (MATCH("NULLIFEXPR", 10))
+		return_value = _readNullIfExpr();
 	else if (MATCH("NULLTEST", 8))
 		return_value = _readNullTest();
 	else if (MATCH("BOOLEANTEST", 11))
-- 
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