Support "variadic" functions, which can accept a variable number of arguments

so long as all the trailing arguments are of the same (non-array) type.
The function receives them as a single array argument (which is why they
have to all be the same type).

It might be useful to extend this facility to aggregates, but this patch
doesn't do that.

This patch imposes a noticeable slowdown on function lookup --- a follow-on
patch will fix that by adding a redundant column to pg_proc.

Pavel Stehule

1 files changed, 16 insertions, 20 deletions

diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 362108ba3fa..8addb53e51e 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.228 2008/04/29 14:59:16 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.229 2008/07/16 01:30:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -358,8 +358,8 @@ transformIndirection(ParseState *pstate, Node *basenode, List *indirection)
 			result = ParseFuncOrColumn(pstate,
 									   list_make1(n),
 									   list_make1(result),
-									   false, false, true,
-									   -1);
+									   false, false, false,
+									   true, -1);
 		}
 	}
 	/* process trailing subscripts, if any */
@@ -481,8 +481,8 @@ transformColumnRef(ParseState *pstate, ColumnRef *cref)
 					node = ParseFuncOrColumn(pstate,
 											 list_make1(makeString(name2)),
 											 list_make1(node),
-											 false, false, true,
-											 cref->location);
+											 false, false, false,
+											 true, cref->location);
 				}
 				break;
 			}
@@ -511,8 +511,8 @@ transformColumnRef(ParseState *pstate, ColumnRef *cref)
 					node = ParseFuncOrColumn(pstate,
 											 list_make1(makeString(name3)),
 											 list_make1(node),
-											 false, false, true,
-											 cref->location);
+											 false, false, false,
+											 true, cref->location);
 				}
 				break;
 			}
@@ -552,8 +552,8 @@ transformColumnRef(ParseState *pstate, ColumnRef *cref)
 					node = ParseFuncOrColumn(pstate,
 											 list_make1(makeString(name4)),
 											 list_make1(node),
-											 false, false, true,
-											 cref->location);
+											 false, false, false,
+											 true, cref->location);
 				}
 				break;
 			}
@@ -1018,25 +1018,21 @@ transformFuncCall(ParseState *pstate, FuncCall *fn)
 	List	   *targs;
 	ListCell   *args;
 
-	/*
-	 * Transform the list of arguments.  We use a shallow list copy and then
-	 * transform-in-place to avoid O(N^2) behavior from repeated lappend's.
-	 *
-	 * XXX: repeated lappend() would no longer result in O(n^2) behavior;
-	 * worth reconsidering this design?
-	 */
-	targs = list_copy(fn->args);
-	foreach(args, targs)
+	/* Transform the list of arguments ... */
+	targs = NIL;
+	foreach(args, fn->args)
 	{
-		lfirst(args) = transformExpr(pstate,
-									 (Node *) lfirst(args));
+		targs = lappend(targs, transformExpr(pstate,
+											 (Node *) lfirst(args)));
 	}
 
+	/* ... and hand off to ParseFuncOrColumn */
 	return ParseFuncOrColumn(pstate,
 							 fn->funcname,
 							 targs,
 							 fn->agg_star,
 							 fn->agg_distinct,
+							 fn->func_variadic,
 							 false,
 							 fn->location);
 }