add pass uniquify_var and interp_var

ocaml_yacc/calc.ml

@@ -7,22 +7,33 @@ let rec ast_to_string ast = match ast with
 | Ast.Node ls -> "[" ^ String.concat " " (List.map ast_to_string ls) ^ "]"
 ;;
 
-(** interpreter for interp_int*)
-class interp_int x_init =
+(**environment for the interpreter*)
+class environment =
     object (self)
-      val mutable x = x_init
-      method interp code = match code with
+      val mutable tbl : (string, int) Hashtbl.t = Hashtbl.create 10
+      method add_val key data = Hashtbl.add tbl key data
+      method get_val key = Hashtbl.find tbl key
+	  method get_tbl = tbl
+    end;;
+
+
+
+
+(** interpreter for interp_int*)
+class interp_int =
+    object (self)
+      method interp (env : environment) code = match code with
 		| Ast.Int x -> x
 		| Ast.Node [Ast.Leaf "+"; lhs; rhs] ->
-			let x1 = self#interp lhs in
-			let x2 = self#interp rhs in
+			let x1 = self#interp env lhs in
+			let x2 = self#interp env rhs in
 			x1+x2 
 		| Ast.Node [Ast.Leaf "-"; lhs; rhs] ->
-			let x1 = self#interp lhs in
-			let x2 = self#interp rhs in
+			let x1 = self#interp env lhs in
+			let x2 = self#interp env rhs in
 			x1-x2 
 		| Ast.Node [Ast.Leaf "-"; x] ->
-			let x1 = self#interp x in
+			let x1 = self#interp env x in
 			0-x1 
 		| Ast.Node [Ast.Leaf "%apply" ; Ast.Leaf "read"; Ast.Int 0] ->
 			let input = read_int_opt () in
@@ -32,6 +43,45 @@ class interp_int x_init =
 		| _ -> raise (Exc "unsupported")
     end;;
 
+(** interpreter for interp_var*)
+class interp_var = 
+	object (self)
+      inherit interp_int as super
+		method interp (env : environment) code = match code with
+			| Ast.Leaf var -> env#get_val var
+			| Ast.Node [Ast.Leaf "%let"; Ast.Node[typ; Ast.Leaf var; data]; body] ->
+				let new_val = self#interp env data in
+				let _ = env#add_val var new_val in
+				self#interp env body
+
+			| _ -> super#interp env code
+end;;
+
+let prime_op = ["+"; "-"];;
+
+(** PASS1 : uniquify the variable*)
+let rec uniquify_var_pass ast (tbl : (string, int) Hashtbl.t) = match ast with
+	| Ast.Int x -> ast
+	| Ast.Leaf var -> Ast.Leaf (var ^ "." ^ (string_of_int(Hashtbl.find tbl var)))
+	| Ast.Node [Ast.Leaf "-" ; x] ->  Ast.Node [Ast.Leaf "-"; uniquify_var_pass x tbl]
+
+
+	| Ast.Node [Ast.Leaf "%let"; Ast.Node[typ; Ast.Leaf var; data]; body] ->
+		let _ = if not(Hashtbl.mem tbl var) then
+				(Hashtbl.add tbl var 0) else
+				Hashtbl.replace tbl var ((Hashtbl.find tbl var)+1) in
+		let new_var = Ast.Leaf (var ^ "." ^(string_of_int(Hashtbl.find tbl var))) in
+		let rhs = uniquify_var_pass data tbl in
+		Ast.Node [Ast.Leaf "%let"; Ast.Node[typ; new_var; rhs];
+	uniquify_var_pass body tbl]
+	| Ast.Node [Ast.Leaf op ; lhs; rhs] -> if List.mem op prime_op  then
+													Ast.Node [Ast.Leaf op ;
+													uniquify_var_pass lhs tbl;
+													uniquify_var_pass rhs tbl] else
+													Ast.Node [uniquify_var_pass (Ast.Leaf op) tbl;
+													uniquify_var_pass lhs tbl;
+													uniquify_var_pass rhs tbl]
+	| _ -> ast
 
 
 
@@ -39,10 +89,14 @@ class interp_int x_init =
         let _ =
           try
             let lexbuf = Lexing.from_channel stdin in
-			let interp = new interp_int 0 in
+			let env = new environment in
+			let interp = new interp_var in
             while true do
+			  let hasht = (Hashtbl.create 10) in
               let result = Parser.main Lexer.token lexbuf in
-                Printf.printf "%d" (interp#interp result); print_newline(); flush stdout
+			  let result2 = uniquify_var_pass result hasht in 
+				Printf.printf "%s\n" (ast_to_string result2);
+                Printf.printf "%d" (interp#interp env result2); print_newline(); flush stdout
             done
           with Lexer.Eof ->
             exit 0