Question 8

pfx/basic/lexer.mll

 (* Question 6.1 et 6.2 *)
 {
-  (* open Parser
-  open Ast *)
+  open Parser
+  (* open Ast *)
   open Utils
 
-  type token =
-    | EOF | PUSH | POP | SWAP | ADD | SUB | MUL | DIV | REM | INT of int
-
-  let print_token = function
-    | EOF -> print_string "EOF"
-    | INT i -> print_int i
-    | PUSH -> print_string "PUSH"
-    | SWAP -> print_string "SWAP"
-    | POP -> print_string "POP"
-    | ADD -> print_string "ADD"
-    | SUB -> print_string "SUB"
-    | MUL -> print_string "MUL"
-    | DIV -> print_string "DIV"
-    | REM -> print_string "REM"
-
   let mk_int nb lexbuf =
     try INT (int_of_string nb)
     with Failure _ -> failwith (Location.string_of (Location.curr lexbuf))
@@ -51,27 +36,3 @@ rule token = parse
   | "rem" {REM}
   (* illegal characters *)
   | _                  { failwith (Location.string_of (Location.curr lexbuf)) }
\ No newline at end of file
-
-{
-  let rec examine_all lexbuf =
-    let result = token lexbuf in
-    print_token result;
-    print_string " ";
-    match result with
-    | EOF -> ()
-    | _   -> examine_all lexbuf
-
-  let compile file =
-  print_string ("File "^file^" is being treated!\n");
-  try
-    let input_file = open_in file in
-    let lexbuf = Lexing.from_channel input_file in
-    Location.init lexbuf file;
-    examine_all lexbuf;
-    print_newline ();
-    close_in (input_file)
-  with Sys_error _ ->
-    print_endline ("Can't find file '" ^ file ^ "'")
-
-  let _ = Arg.parse [] compile ""
-}
\ No newline at end of file

pfx/basic/parser.mly

 %{
-  (* Ocaml code here*)
-
+  open Ast
 %}
 
 (**************
  * The tokens *
  **************)
 
-(* enter tokens here, they should begin with %token *)
-%token EOF
+%token EOF PUSH POP SWAP ADD SUB MUL DIV REM
 %token <int> INT
 
 
@@ -16,7 +14,6 @@
  * Entry points of the parser *
  ******************************)
 
-(* enter your %start clause here *)
 %start <Ast.program> program
 
 %%
@@ -25,8 +22,20 @@
  * The rules *
  *************)
 
-(* list all rules composing your grammar; obviously your entry point has to be present *)
-
-program: i=INT EOF { i,[] }
+program: 
+  | i=INT; c=command { i, c }
+  | EOF { 0, [] }
+
+command: 
+  | PUSH command { failwith ("Argument missing for push function") }
+  | PUSH i=INT c=command { (Push i)::c }
+  | POP c=command { Pop::c }
+  | SWAP c=command { Swap::c }
+  | ADD c=command { Add::c }
+  | SUB c=command { Sub::c }
+  | MUL c=command { Mul::c }
+  | DIV c=command { Div::c }
+  | REM c=command { Rem::c }
+  | EOF { [] }
 
 %%

pfx/basic/tests/ok_prog.pfx

-0 push 2 push 7 push 3 add div -- -5
+0 push 2 push 4 swap

pfx/dune

+(executables
+ (names pfxVM)
+ (libraries utils basicPfx))