(***********************************************

  piece.ml
  Define pieces in the game
  Copyright (C) 2001 Brock Wilcox
  [awwaiid@deathonastick.org]
  Released under the terms of the GNU GPL
  See www.gnu.org for more information

  HISTORY / NOTES

  2001.04.07.22.48
   - Split off from game_utils.ml
  2001.02.25.06.19
   - do_move now returns () and raises error
   - Added rand_move and rand_piece
  2001.01.29.04.49
   - Tweaked the human input a bit
   - All rules implemented
  2000.11.02.14.00
   - Most rules implemented
   - Only needs winner routine
  2000.10.27.10.35
   - Created

***********************************************)


exception Error of string


(* The different types of things that can be on the board *)
type piece =
  | X
  | O
  | Blank

let to_int = function
  | X -> 1
  | O -> 2
  | Blank -> 0

(* Copy a piece *)
let copy = function
  | X -> X
  | O -> O
  | Blank -> Blank


(* Print out a piece *)
let print = function
  | X     -> print_char 'X'
  | O     -> print_char 'O'
  | Blank -> print_char ' '


(* Pick a random piece (X or O, not Blank) *)
(* There must be a prettier way of doing this *)
let rand () =
  match (Random.int 2) with
    | 0 -> X
    | 1 -> O
    | _ -> raise (Error "rand_piece")


(* Get the opposite of a piece *)
let opposite = function
  | X -> O
  | O -> X
  | Blank -> Blank


(* End of piece.ml *)