Re: [Caml-list] Calling parser from inside a parser rule

[Damien Pous <Damien.Pous@ens-lyon.fr>]

hi,

why don't you recurse before the parser level ?

lexer.mll:
<<
{ type token = [`Print | `Arf | `Eof] }

let blank = [' ' '\r' '\t' '\n']*
let word = [ 'a'-'z' '.' ]*

rule token = parse
  | blank   { token lexbuf }
  | "#include" blank '"' (word as s) '"' { `Include s }
  | "print" { `Print }
  | "arf"   { `Arf }
      (* ... *) 
  | eof     { `Eof }
>>

reclexer.mll
<<
let token lexbuf: unit -> Lexer.token =
  let acc = ref [lexbuf] in
  let rec aux () = match !acc with
    | [] -> `Eof
    | (x::q) as l -> 
	match Lexer.token x with
	  | `Include s -> acc := (Lexing.from_channel (open_in s))::l; aux()
	  | `Eof -> acc := q; aux()
	  | #Lexer.token as t -> t
  in aux
>>

let t = token (Lexing.from_channel (open_in "toto"));;
t();;
t();;
...

of course you have to handle cyclic includes...

damien

On Sun, 19 Sep 2004 08:50:42 -0700
James Lamanna <jamesl@appliedminds.com> wrote:
> Essentially.
> I want to be able to recurse into my parser.

-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners