Promote row expressions to full-fledged citizens of the expression syntax,

rather than allowing them only in a few special cases as before.  In
particular you can now pass a ROW() construct to a function that accepts
a rowtype parameter.  Internal generation of RowExprs fixes a number of
corner cases that used to not work very well, such as referencing the
whole-row result of a JOIN or subquery.  This represents a further step in
the work I started a month or so back to make rowtype values into
first-class citizens.

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.280 2004/05/05 04:48:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.281 2004/05/10 22:44:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -998,6 +998,21 @@ _copyArrayExpr(ArrayExpr *from)
 	return newnode;
 }
 
+/*
+ * _copyRowExpr
+ */
+static RowExpr *
+_copyRowExpr(RowExpr *from)
+{
+	RowExpr  *newnode = makeNode(RowExpr);
+
+	COPY_NODE_FIELD(args);
+	COPY_SCALAR_FIELD(row_typeid);
+	COPY_SCALAR_FIELD(row_format);
+
+	return newnode;
+}
+
 /*
  * _copyCoalesceExpr
  */
@@ -2674,6 +2689,9 @@ copyObject(void *from)
 		case T_ArrayExpr:
 			retval = _copyArrayExpr(from);
 			break;
+		case T_RowExpr:
+			retval = _copyRowExpr(from);
+			break;
 		case T_CoalesceExpr:
 			retval = _copyCoalesceExpr(from);
 			break;

src/backend/nodes/equalfuncs.c

@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.219 2004/05/05 04:48:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.220 2004/05/10 22:44:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -423,6 +423,24 @@ _equalArrayExpr(ArrayExpr *a, ArrayExpr *b)
 	return true;
 }
 
+static bool
+_equalRowExpr(RowExpr *a, RowExpr *b)
+{
+	COMPARE_NODE_FIELD(args);
+	COMPARE_SCALAR_FIELD(row_typeid);
+
+	/*
+	 * Special-case COERCE_DONTCARE, so that planner can build coercion
+	 * nodes that are equal() to both explicit and implicit coercions.
+	 */
+	if (a->row_format != b->row_format &&
+		a->row_format != COERCE_DONTCARE &&
+		b->row_format != COERCE_DONTCARE)
+		return false;
+
+	return true;
+}
+
 static bool
 _equalCoalesceExpr(CoalesceExpr *a, CoalesceExpr *b)
 {
@@ -1748,6 +1766,9 @@ equal(void *a, void *b)
 		case T_ArrayExpr:
 			retval = _equalArrayExpr(a, b);
 			break;
+		case T_RowExpr:
+			retval = _equalRowExpr(a, b);
+			break;
 		case T_CoalesceExpr:
 			retval = _equalCoalesceExpr(a, b);
 			break;

src/backend/nodes/makefuncs.c

@@ -9,12 +9,13 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/makefuncs.c,v 1.42 2003/11/29 19:51:49 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/makefuncs.c,v 1.43 2004/05/10 22:44:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
 
+#include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "utils/lsyscache.h"
 
@@ -170,6 +171,17 @@ makeNullConst(Oid consttype)
 					 typByVal);
 }
 
+/*
+ * makeBoolConst -
+ *	  creates a Const node representing a boolean value (can be NULL too)
+ */
+Node *
+makeBoolConst(bool value, bool isnull)
+{
+	/* note that pg_type.h hardwires size of bool as 1 ... duplicate it */
+	return (Node *) makeConst(BOOLOID, 1, BoolGetDatum(value), isnull, true);
+}
+
 /*
  * makeBoolExpr -
  *	  creates a BoolExpr node

src/backend/nodes/outfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.235 2004/05/08 21:21:18 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.236 2004/05/10 22:44:44 tgl Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -828,6 +828,16 @@ _outArrayExpr(StringInfo str, ArrayExpr *node)
 	WRITE_BOOL_FIELD(multidims);
 }
 
+static void
+_outRowExpr(StringInfo str, RowExpr *node)
+{
+	WRITE_NODE_TYPE("ROW");
+
+	WRITE_NODE_FIELD(args);
+	WRITE_OID_FIELD(row_typeid);
+	WRITE_ENUM_FIELD(row_format, CoercionForm);
+}
+
 static void
 _outCoalesceExpr(StringInfo str, CoalesceExpr *node)
 {
@@ -1719,6 +1729,9 @@ _outNode(StringInfo str, void *obj)
 			case T_ArrayExpr:
 				_outArrayExpr(str, obj);
 				break;
+			case T_RowExpr:
+				_outRowExpr(str, obj);
+				break;
 			case T_CoalesceExpr:
 				_outCoalesceExpr(str, obj);
 				break;

src/backend/nodes/readfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.168 2004/05/08 21:21:18 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.169 2004/05/10 22:44:44 tgl Exp $
  *
  * NOTES
  *	  Path and Plan nodes do not have any readfuncs support, because we
@@ -628,6 +628,21 @@ _readArrayExpr(void)
 	READ_DONE();
 }
 
+/*
+ * _readRowExpr
+ */
+static RowExpr *
+_readRowExpr(void)
+{
+	READ_LOCALS(RowExpr);
+
+	READ_NODE_FIELD(args);
+	READ_OID_FIELD(row_typeid);
+	READ_ENUM_FIELD(row_format, CoercionForm);
+
+	READ_DONE();
+}
+
 /*
  * _readCoalesceExpr
  */
@@ -978,6 +993,8 @@ parseNodeString(void)
 		return_value = _readCaseTestExpr();
 	else if (MATCH("ARRAY", 5))
 		return_value = _readArrayExpr();
+	else if (MATCH("ROW", 3))
+		return_value = _readRowExpr();
 	else if (MATCH("COALESCE", 8))
 		return_value = _readCoalesceExpr();
 	else if (MATCH("NULLIFEXPR", 10))