Give 'a_expr ::= a_expr Op' production a slightly lower precedence than

Op, so that the sequence 'a_expr Op Op a_expr' will be parsed as
a_expr Op (Op a_expr) not (a_expr Op) Op a_expr as formerly.  In other
words, prefer treating user-defined operators as prefix operators to
treating them as postfix operators, when there is an ambiguity.
Also clean up a couple of other infelicities in production priority
assignment --- for example, BETWEEN wasn't being given the intended
priority, but that of AND.

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 36690cf1e68df47a1781fc1bc93dcbfc7d70a414..dfa97e797319b975379e6c87b16b8afea18c0d46 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.217 2001/01/20 17:37:52 tgl Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.218 2001/01/23 22:39:08 tgl Exp $
  *
  * HISTORY
  *       AUTHOR                        DATE                    MAJOR EVENT
@@ -383,16 +383,16 @@ static void doNegateFloat(Value *v);
 %nonassoc      OVERLAPS
 %nonassoc      BETWEEN
 %nonassoc      IN
+%left          POSTFIXOP               /* dummy for postfix Op rules */
 %left          Op                              /* multi-character ops and user-defined operators */
 %nonassoc      NOTNULL
 %nonassoc      ISNULL
-%nonassoc      NULL_P
-%nonassoc      IS
+%nonassoc      IS NULL_P TRUE_P FALSE_P        /* sets precedence for IS NULL, etc */
 %left          '+' '-'
 %left          '*' '/' '%'
 %left          '^'
 /* Unary Operators */
-%left          AT
+%left          AT ZONE                 /* sets precedence for AT TIME ZONE */
 %right         UMINUS
 %left          '.'
 %left          '[' ']'
@@ -4355,7 +4355,7 @@ a_expr:  c_expr
                                {       $$ = makeA_Expr(OP, $2, $1, $3); }
                | Op a_expr
                                {       $$ = makeA_Expr(OP, $1, NULL, $2); }
-               | a_expr Op
+               | a_expr Op                                     %prec POSTFIXOP
                                {       $$ = makeA_Expr(OP, $2, $1, NULL); }
 
                | a_expr AND a_expr
@@ -4463,13 +4463,13 @@ a_expr:  c_expr
                                        n->typename->typmod = -1;
                                        $$ = makeA_Expr(OP, "=", $1,(Node *)n);
                                }
-               | a_expr BETWEEN b_expr AND b_expr
+               | a_expr BETWEEN b_expr AND b_expr                      %prec BETWEEN
                                {
                                        $$ = makeA_Expr(AND, NULL,
                                                makeA_Expr(OP, ">=", $1, $3),
                                                makeA_Expr(OP, "<=", $1, $5));
                                }
-               | a_expr NOT BETWEEN b_expr AND b_expr
+               | a_expr NOT BETWEEN b_expr AND b_expr          %prec BETWEEN
                                {
                                        $$ = makeA_Expr(OR, NULL,
                                                makeA_Expr(OP, "<", $1, $4),
@@ -4529,7 +4529,7 @@ a_expr:  c_expr
                                                $$ = n;
                                        }
                                }
-               | a_expr all_Op sub_type select_with_parens
+               | a_expr all_Op sub_type select_with_parens             %prec Op
                                {
                                        SubLink *n = makeNode(SubLink);
                                        n->lefthand = makeList1($1);
@@ -4591,7 +4591,7 @@ b_expr:  c_expr
                                {       $$ = makeA_Expr(OP, $2, $1, $3); }
                | Op b_expr
                                {       $$ = makeA_Expr(OP, $1, NULL, $2); }
-               | b_expr Op
+               | b_expr Op                                     %prec POSTFIXOP
                                {       $$ = makeA_Expr(OP, $2, $1, NULL); }
                ;