lib/interned.ml

   1 (*pp deriving *)
   2
   3 (* Copyright Jeremy Yallop 2007.
   4    This file is free software, distributed under the MIT license.
   5    See the file COPYING for details.
   6 *)
   7
   8 (* Interned strings *)
   9 module StringMap = Map.Make(String)
  10
  11 (* global state *)
  12 let map = ref StringMap.empty
  13 let counter = ref 0
  14
  15 type t = int * string
  16     deriving (Show)
  17
  18 let intern s =
  19   try StringMap.find s !map
  20   with Not_found ->
  21     let fresh = (!counter, String.copy s) in begin
  22         map := StringMap.add s fresh !map;
  23         incr counter;
  24         fresh
  25       end
  26
  27 let to_string (_,s) = String.copy s
  28 let name = snd
  29 let compare (l,_) (r,_) = compare l r
  30 let eq (l,_) (r,_) = l = r