diff --git a/SQLPGrammar.y b/SQLPGrammar.y
index 2c4791e7b5f442d9021ad1ed172560a9f66009d4..6a5d9a5a50771f4e1251188c1fba1cd4ebee1731 100644
--- a/SQLPGrammar.y
+++ b/SQLPGrammar.y
@@ -21,11 +21,14 @@
 SQLPQuery
 	: Query
 	{
-		$$ = NULL;
+		create_constant("TEST", "10");
+		$$ = create_cons_cell_w_atom("SQLP_QUERY", create_cons_cell_w_atom("QUERY", $1));
+		print_cons_tree($$);
 	}
 	| Body
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("SQLP_QUERY", create_cons_cell_w_atom("BODY", $1));
+		print_cons_tree($$);
 	};
 
 Query
@@ -41,85 +44,85 @@ Query
 Body
 	: Pred
 	{
-		$$ = NULL;
+		$$ = create_list("PRED", $1);
 	}
 	| Atom
 	{
-		$$ = NULL;
+		$$ = $1;
 	}
 	| NaturalJoinList
 	{
-		$$ = NULL;
+		$$ = create_list("NATURAL_JOIN", $1);
 	}
 	| SubQuery
 	{
-		$$ = NULL;
+		$$ = $1;
 	};
 
 Atom
 	: TableIdentifier VarIdentifier
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("ATOM", create_cons_cell($1, create_cons_cell($2, NULL)));
 	};
 
 NaturalJoinList
-	: NaturalJoinList JOIN '(' Body ')'
+	: '(' Body ')' JOIN NaturalJoinList
 	{
-		$$ = NULL;
+		$$ = create_cons_cell($2, $5);
 	}
 	| '(' Body ')'
 	{
-		$$ = NULL;
+		$$ = create_cons_cell($2, NULL);
 	};
 
 SubQuery
 	: Query VarIdentifier
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("SUB_QUERY", create_cons_cell($2, NULL));
 	};
 
 Select
 	: SELECT SetOrBag Limit AsList Body
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("SELECT", create_cons_cell($2, create_cons_cell($3, create_cons_cell(create_list("AS", $4), create_cons_cell($5, NULL)))));
 	};
 
 SetOrBag
 	: DISTINCT
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("DISTINCT", NULL);
 	}
 	| ALL
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("ALL", NULL);
 	}
 	| /* empty */
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("ALL", NULL);
 	};
 
 Limit
-	: LIMIT INTEGER
+	: LIMIT Integer
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("LIMIT", $2);
 	}
 	| NOLIMIT
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("NO_LIMIT", NULL);
 	}
 	| /* empty */
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("NO_LIMIT", NULL);
 	};
 
 AsList
 	: As
 	{
-		$$ = $1;
+		$$ = create_cons_cell($1, NULL);
 	}
-	| AsList ',' As
+	| As ',' AsList
 	{
-		$$ = NULL;
+		$$ = create_cons_cell($1, $3);
 	};
 
 As
@@ -129,116 +132,121 @@ As
 	}
 	| Col AS AttrIdentifier
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("AS", create_cons_cell($1, create_cons_cell($3, NULL)));
 	};
 
 Union
 	: UNION SetOrBag Limit QueryList
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("UNION", create_cons_cell($2, create_cons_cell($3, create_cons_cell(create_list("QUERY", $4), NULL))));
 	};
 
 QueryList
-	: QueryList ',' '(' Query ')'
+	: '(' Query ')' ',' QueryList
 	{
-		$$ = NULL;
+		$$ = create_cons_cell($2, $5);
 	}
 	| '(' Query ')'
 	{
-		$$ = NULL;
+		$$ = create_cons_cell($2, NULL);
 	}
 
 Col
 	: VarIdentifier '.' AttributePath
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("COL", create_cons_cell($1, create_cons_cell(create_list("ATTRIBUTE", $3), NULL)));
   };
 
-AttributePath
-	: AttrIdentifier
-	{
-		$$ = NULL;
-	};
-	| AttributePath '.' AttrIdentifier
-	{
-		$$ = NULL;
-	};
-
-VarIdentifier
-	: IDENTIFIER
-	{
-		$$ = NULL;
-	};
-
-
-TableIdentifier
-	: IDENTIFIER
-	{
-		$$ = NULL;
-	};
-
-AttrIdentifier
-	: IDENTIFIER
-	{
-		$$ = NULL;
-	};
-
 Pred
 	: Conj
 	{
-		$$ = NULL;
+		$$ = create_cons_cell(create_list("CONJ", $1), NULL);
 	}
 	| '(' Conj OR Pred ')'
 	{
-		$$ = NULL;
+		$$ = create_cons_cell(create_list("CONJ", $2), $4);
 	};
 
 Conj
 	: BasicPred
 	{
-		$$ = NULL;
+		$$ = create_cons_cell($1, NULL);
 	}
 	| '(' BasicPred AND Conj ')'
 	{
-		$$ = NULL;
+		$$ = create_cons_cell($2, $4);
 	}
 
 BasicPred
 	: Term '=' Term
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("EQUAL", create_cons_cell($1, create_cons_cell($3, NULL)));
 	}
 	| Term '<' Term
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("LT", create_cons_cell($1, create_cons_cell($3, NULL)));
 	}
 	| Term LE Term
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("LE", create_cons_cell($1, create_cons_cell($3, NULL)));
 	}
 	| EXISTS Body
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("EXISTS", create_cons_cell($2, NULL));
 	}
 	| NOT Pred
 	{
-		$$ = NULL;
+		$$ = create_cons_cell_w_atom("NOT", create_cons_cell($2, NULL));
 	};
 
 Term
 	: INTEGER
 	{
-		$$ = NULL;
+		$$ = create_constant("INTEGER", constant);
 	}
 	| REAL
 	{
-		$$ = NULL;
+		$$ = create_constant("REAL", constant);
 	}
 	| STRING
 	{
-		$$ = NULL;
+		$$ = create_constant("STRING", constant);
 	}
 	| Col
 	{
 		$$ = $1;
 	};
+
+AttributePath
+	: AttrIdentifier
+	{
+		$$ = create_cons_cell($1, NULL);
+	};
+	| AttrIdentifier '.' AttributePath
+	{
+		$$ = create_cons_cell($1, $3);
+	};
+
+VarIdentifier
+	: IDENTIFIER
+	{
+		$$ = create_identifier("VAR", identifier);
+	};
+
+TableIdentifier
+	: IDENTIFIER
+	{
+		$$ = create_identifier("TABLE", identifier);
+	};
+
+AttrIdentifier
+	: IDENTIFIER
+	{
+		$$ = create_identifier("ATTR", identifier);
+	};
+
+Integer
+	: INTEGER
+	{
+		$$ = create_constant("INTEGER", constant);
+	};
diff --git a/util.c b/util.c
index cd25ca23fc919c3a913847a3d49cade763eab6d8..5f82b6afedebe1c7a4cf557dff54a648cce32a4f 100644
--- a/util.c
+++ b/util.c
@@ -47,6 +47,12 @@ cons_cell* create_identifier(char *type, char *identifier) {
 	return create_cons_cell_w_atom(str, cc);
 }
 
+cons_cell * create_constant(char *type, char *val) {
+	printf("create_constant: %s, %s\n", type, val);
+	cons_cell* cc = create_cons_cell_w_atom(val, NULL);
+	return create_cons_cell_w_atom(type, cc);
+}
+
 cons_cell * create_list(char *type, cons_cell *list) {
 	printf("create_list: %s\n", type);
 	char str[100];
diff --git a/util.h b/util.h
index 4b33bc97aae5f180596099a8024bff3032665797..0bf84525d79ca5f79244408ad9485e4652e209dc 100644
--- a/util.h
+++ b/util.h
@@ -35,6 +35,8 @@ cons_cell * cdr(cons_cell * cc);
 
 cons_cell * create_identifier(char *type, char *identifier);
 
+cons_cell * create_constant(char *type, char *val);
+
 cons_cell * create_list(char *type, cons_cell *list);
 
 void print_cons_tree(cons_cell *cc);