diff options
| -rw-r--r-- | src/backend/parser/gram.y | 34 |
1 files changed, 15 insertions, 19 deletions
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index 017940bdcd6..17653ef3a79 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -744,22 +744,15 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query); %nonassoc BETWEEN IN_P LIKE ILIKE SIMILAR NOT_LA %nonassoc ESCAPE /* ESCAPE must be just above LIKE/ILIKE/SIMILAR */ /* - * To support target_el without AS, we must give IDENT an explicit priority - * between ESCAPE and Op. We can safely assign the same priority to - * various unreserved keywords as needed to resolve ambiguities (this can't - * have any bad effects since obviously the keywords will still behave the - * same as if they weren't keywords). We need to do this: - * for PARTITION, RANGE, ROWS, GROUPS to support opt_existing_window_name; - * for RANGE, ROWS, GROUPS so that they can follow a_expr without creating - * postfix-operator problems; - * for GENERATED so that it can follow b_expr; - * and for NULL so that it can follow b_expr in ColQualList without creating - * postfix-operator problems. + * To support target_el without AS, it used to be necessary to assign IDENT an + * explicit precedence just less than Op. While that's not really necessary + * since we removed postfix operators, it's still helpful to do so because + * there are some other unreserved keywords that need precedence assignments. + * If those keywords have the same precedence as IDENT then they clearly act + * the same as non-keywords, reducing the risk of unwanted precedence effects. * - * To support CUBE and ROLLUP in GROUP BY without reserving them, we give them - * an explicit priority lower than '(', so that a rule with CUBE '(' will shift - * rather than reducing a conflicting rule that takes CUBE as a function name. - * Using the same precedence as IDENT seems right for the reasons given above. + * We need to do this for PARTITION, RANGE, ROWS, and GROUPS to support + * opt_existing_window_name (see comment there). * * The frame_bound productions UNBOUNDED PRECEDING and UNBOUNDED FOLLOWING * are even messier: since UNBOUNDED is an unreserved keyword (per spec!), @@ -769,9 +762,14 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query); * appear to cause UNBOUNDED to be treated differently from other unreserved * keywords anywhere else in the grammar, but it's definitely risky. We can * blame any funny behavior of UNBOUNDED on the SQL standard, though. + * + * To support CUBE and ROLLUP in GROUP BY without reserving them, we give them + * an explicit priority lower than '(', so that a rule with CUBE '(' will shift + * rather than reducing a conflicting rule that takes CUBE as a function name. + * Using the same precedence as IDENT seems right for the reasons given above. */ -%nonassoc UNBOUNDED /* ideally should have same precedence as IDENT */ -%nonassoc IDENT GENERATED NULL_P PARTITION RANGE ROWS GROUPS PRECEDING FOLLOWING CUBE ROLLUP +%nonassoc UNBOUNDED /* ideally would have same precedence as IDENT */ +%nonassoc IDENT PARTITION RANGE ROWS GROUPS PRECEDING FOLLOWING CUBE ROLLUP %left Op OPERATOR /* multi-character ops and user-defined operators */ %left '+' '-' %left '*' '/' '%' @@ -792,8 +790,6 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query); * left-associativity among the JOIN rules themselves. */ %left JOIN CROSS LEFT FULL RIGHT INNER_P NATURAL -/* kluge to keep xml_whitespace_option from causing shift/reduce conflicts */ -%right PRESERVE STRIP_P %% |