Support a_expr typecasting

Author: JoshInnis

regress/expected/new_cypher.out

@@ -15,6 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */ 
 -- Regression tests don't preload extensions, gotta load it first
+SET search_path TO postgraph;
 LOAD 'postgraph';
 CREATE EXTENSION postgraph;
 ERROR:  extension "postgraph" already exists
@@ -212,6 +213,12 @@ SELECT * FROM tst;
  Hello
 (1 row)
 
+SELECT '"Hello"'::gtype = '"Hello"'::gtype;
+ ?column? 
+----------
+ t
+(1 row)
+
 DROP GRAPH new_cypher CASCADE;
 NOTICE:  drop cascades to 2 other objects
 DETAIL:  drop cascades to table new_cypher._ag_label_vertex

regress/sql/new_cypher.sql

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */ 
 -- Regression tests don't preload extensions, gotta load it first
-
+SET search_path TO postgraph;
 LOAD 'postgraph';
 
 CREATE EXTENSION postgraph;
@@ -108,5 +108,7 @@ INSERT INTO tst SELECT 'Hello';
 
 SELECT * FROM tst;
 
+SELECT '"Hello"'::gtype = '"Hello"'::gtype;
+
 DROP GRAPH new_cypher CASCADE;
 DROP GRAPH new_cypher_2 CASCADE;

src/backend/parser/cypher_gram.y

@@ -642,9 +642,6 @@ simple_select:
 				}
 		;
 
-
-
-
 opt_all_clause:
 			ALL
 			| /*EMPTY*/
@@ -2142,9 +2139,9 @@ indirection_el:
  * you expect!  So we use %prec annotations freely to set precedences.
  */
 a_expr:		c_expr									{ $$ = $1; }
-			/*| a_expr TYPECAST Typename
+			| a_expr TYPECAST Typename
 					{ $$ = makeTypeCast($1, $3, @2); }
-			| a_expr COLLATE any_name
+			/*| a_expr COLLATE any_name
 				{
 					CollateClause *n = makeNode(CollateClause);
 					n->arg = $1;