Clean Util Grammar Rule Stmts

Make it look more Postgres like.

Author: JoshInnis

regress/expected/cypher_match.out

@@ -244,14 +244,11 @@ ERROR:  operator does not exist: postgraph.graphid = postgraph.graphid
 HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
 -- Property Constraint in EXISTS
 MATCH (u) WHERE EXISTS((u)-[]->({id: "middle"})) RETURN u;
-ERROR:  operator does not exist: postgraph.gtype @> postgraph.gtype
-HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+ERROR:  MATCH cannot be the last clause in a cypher statement
 MATCH (u) WHERE EXISTS((u)-[]->({id: "not a valid id"})) RETURN u;
-ERROR:  operator does not exist: postgraph.gtype @> postgraph.gtype
-HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+ERROR:  MATCH cannot be the last clause in a cypher statement
 MATCH (u) WHERE EXISTS((u)-[]->({id: NULL})) RETURN u;
-ERROR:  operator does not exist: postgraph.gtype @> postgraph.gtype
-HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+ERROR:  MATCH cannot be the last clause in a cypher statement
 -- Exists checks for a loop. There shouldn't be any.
 MATCH (u)-[e]->(v) WHERE EXISTS((u)-[e]->(u)) RETURN u, e, v;
 ERROR:  operator does not exist: postgraph.graphid = postgraph.graphid
@@ -331,8 +328,7 @@ MATCH (u) RETURN case WHEN EXISTS(MATCH (u)-[]->() RETURN 1) THEN 1 ELSE 2 END;
 ERROR:  operator does not exist: postgraph.graphid = postgraph.graphid
 HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
 MATCH (u) RETURN case WHEN EXISTS((u)-[]->()) THEN 1 ELSE 2 END;
-ERROR:  operator does not exist: postgraph.graphid = postgraph.graphid
-HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+ERROR:  MATCH cannot be the last clause in a cypher statement
 /*
 EXPLAIN
 SELECT *
@@ -446,12 +442,13 @@ LINE 1: ORDER BY n, p, m, q;
 MATCH (n:opt_match_v), (m:opt_match_v)
 WHERE id(n) <> id(m)
 OPTIONAL MATCH (n)-[r]->(p), (m)-[s]->(q)
-RETURN n.name AS n, type(r)
+RETURN n.name AS n, type(r),
            m.name AS m, type(s)
 ORDER BY n, p, m, q;
-ERROR:  syntax error at or near "m"
-LINE 5:            m.name AS m, type(s)
-                   ^
+ERROR:  operator is not unique: postgraph.gtype <> postgraph.gtype
+LINE 2: WHERE id(n) <> id(m)
+                    ^
+HINT:  Could not choose a best candidate operator. You might need to add explicit type casts.
 CREATE (u {name: "orphan"}) CREATE (u1 {name: "F"})-[u2:e1]->(u3 {name: "T"}) RETURN u1, u2, u3;
                                 u1                                 |                                                        u2                                                         |                                u3                                 
 -------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------
@@ -460,12 +457,10 @@ CREATE (u {name: "orphan"}) CREATE (u1 {name: "F"})-[u2:e1]->(u3 {name: "T"}) RE
 
 -- Querying NOT EXISTS syntax
 MATCH (f),(t) WHERE NOT EXISTS((f)-[]->(t)) RETURN f.name, t.name;
-ERROR:  operator does not exist: postgraph.graphid = postgraph.graphid
-HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+ERROR:  MATCH cannot be the last clause in a cypher statement
 -- Querying EXISTS syntax
 MATCH (f),(t) WHERE EXISTS((f)-[]->(t)) RETURN f.name, t.name;
-ERROR:  operator does not exist: postgraph.graphid = postgraph.graphid
-HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+ERROR:  MATCH cannot be the last clause in a cypher statement
 --
 -- Constraints and WHERE clause together
 --
@@ -485,9 +480,7 @@ HINT:  No operator matches the given name and argument types. You might need to
 --
 -- need a following RETURN clause
 MATCH (n:v);
-ERROR:  syntax error at or near ";"
-LINE 1: MATCH (n:v);
-                   ^
+ERROR:  MATCH cannot be the last clause in a cypher statement
 --Invalid Variables
 MATCH (a)-[]-()-[]-(a:v1) RETURN a;
 ERROR:  variable a already exists

src/backend/parser/cypher_gram.y

@@ -118,9 +118,11 @@
 /* query */
 %type <node> stmt
 %type <list> single_query  cypher_stmt
-             use drop
+             
 
-%type <node> util_stmt
+%type <node> CreateExtensionStmt CreateGraphStmt CreateTableStmt
+             DropGraphStmt
+             UseGraphStmt
 %type <node> clause
 
 /* RETURN and WITH clause */
@@ -282,28 +284,17 @@ doNegateFloat(Value *v);
 stmt:
     cypher_stmt semicolon_opt
         {
-            /*
-             * If there is no transition for the lookahead token and the
-             * clauses can be reduced to single_query, the parsing is
-             * considered successful although it actually isn't.
-             *
-             * For example, when `MATCH ... CREATE ... MATCH ... ;` query is
-             * being parsed, there is no transition for the second `MATCH ...`
-             * because the query is wrong but `MATCH .. CREATE ...` is correct
-             * so it will be reduced to query_part_last anyway even if there
-             * are more tokens to read.
-             *
-             * Throw syntax error in this case.
-             */
+
             //if (yychar != YYEOF)
                 //yyerror(&yylloc, scanner, extra, "syntax error");
 
             extra->result = $1;
         }
-    | util_stmt semicolon_opt
-        {
-            extra->result = list_make1($1);
-        } 
+    | CreateGraphStmt semicolon_opt     { extra->result = list_make1($1); }
+    | CreateExtensionStmt semicolon_opt { extra->result = list_make1($1); }
+    | CreateTableStmt semicolon_opt     { extra->result = list_make1($1); }
+    | DropGraphStmt semicolon_opt       { extra->result = list_make1($1); }
+    | UseGraphStmt semicolon_opt        { extra->result = list_make1($1); }
     ;
 
 cypher_stmt:
@@ -329,7 +320,7 @@ cypher_stmt:
         }
     ;
 
-util_stmt:
+CreateGraphStmt:
     CREATE GRAPH IDENTIFIER
         {
 
@@ -338,8 +329,11 @@ util_stmt:
             n->graph_name = $3;
 
             $$ = (Node *)n;
-        } 
-    | CREATE EXTENSION IDENTIFIER create_extension_opt_list
+        }
+        ;
+
+CreateExtensionStmt:
+    CREATE EXTENSION IDENTIFIER create_extension_opt_list
         {
             CreateExtensionStmt *n = makeNode(CreateExtensionStmt);
 
@@ -359,7 +353,10 @@ util_stmt:
 
         	$$ = (Node *) n;
 		}
-    | CREATE OptTemp TABLE qualified_name '(' OptTableElementList ')'
+    ;
+
+CreateTableStmt:
+    CREATE OptTemp TABLE qualified_name '(' OptTableElementList ')'
 			OptInherit OptPartitionSpec table_access_method_clause OptWith
 			//OnCommitOption  OptTableSpace
 				{
@@ -392,10 +389,9 @@ util_stmt:
 					n->if_not_exists = false;
 
 					$$ = (Node *)n;
-				} 
-                | use { $$ = linitial($1); }
-                | drop { $$ = linitial($1); }
-                ;
+				}
+
+
 call_stmt:
     CALL expr_func_norm AS var_name where_opt
         {
@@ -544,25 +540,26 @@ clause:
     | unwind
     ;
 
-use:
+
+UseGraphStmt:
     USE GRAPH IDENTIFIER
     {
         cypher_use_graph *n = make_ag_node(cypher_use_graph);
         n->graph_name = $3;
 
-        $$ = list_make1(n);
+        $$ = n;
     };
 
-drop:
+DropGraphStmt:
     DROP GRAPH IDENTIFIER CASCADE
     {
 
         cypher_drop_graph *n = make_ag_node(cypher_drop_graph);
         n->graph_name = $3;
         n->cascade = true;
 
-        $$ = list_make1(n);
-    }
+        $$ = n;
+    };
 
 cypher_varlen_opt:
     '*' cypher_range_opt