Fix jsonpath unquoted identifiers

Author: Nikita Glukhov

src/backend/utils/adt/jsonpath_gram.y

@@ -275,7 +275,7 @@ makeItemLikeRegex(JsonPathParseItem *expr, string *pattern, string *flags)
 }
 
 %token	<str>		TO_P NULL_P TRUE_P FALSE_P IS_P UNKNOWN_P EXISTS_P
-%token	<str>		STRING_P NUMERIC_P INT_P VARIABLE_P
+%token	<str>		IDENT_P STRING_P NUMERIC_P INT_P VARIABLE_P
 %token	<str>		OR_P AND_P NOT_P
 %token	<str>		LESS_P LESSEQUAL_P EQUAL_P NOTEQUAL_P GREATEREQUAL_P GREATER_P
 %token	<str>		ANY_P STRICT_P LAX_P LAST_P STARTS_P WITH_P LIKE_REGEX_P FLAG_P
@@ -452,7 +452,8 @@ key:
 	;
 
 key_name:
-	STRING_P
+	IDENT_P
+	| STRING_P
 	| TO_P
 	| NULL_P
 	| TRUE_P

src/backend/utils/adt/jsonpath_scan.l

@@ -296,7 +296,7 @@ static keyword keywords[] = {
 static int
 checkSpecialVal()
 {
-	int			res = STRING_P;
+	int			res = IDENT_P;
 	int			diff;
 	keyword		*StopLow = keywords,
 				*StopHigh = keywords + lengthof(keywords),

src/test/regress/expected/jsonb_jsonpath.out

@@ -919,12 +919,6 @@ select jsonb 'null' @* '"123".type()';
  "string"
 (1 row)
 
-select jsonb 'null' @* 'aaa.type()';
- ?column? 
-----------
- "string"
-(1 row)
-
 select jsonb '{"a": 2}' @* '($.a - 5).abs() + 10';
  ?column? 
 ----------