(**************************************************************************) (* *) (* OCaml *) (* *) (* Daniel de Rauglaudre, projet Cristal, INRIA Rocquencourt *) (* *) (* Copyright 1997 Institut National de Recherche en Informatique et *) (* en Automatique. *) (* *) (* All rights reserved. This file is distributed under the terms of *) (* the GNU Lesser General Public License version 2.1, with the *) (* special exception on linking described in the file LICENSE. *) (* *) (**************************************************************************)
type ('e,'a) t = { mutable count : int; mutable data : ('e,'a) data } and ('e,'a) data =
Sempty
| Scons of'a * ('e,'a) data
| Sgen of ('e,'a) gen
| Sbuffio : buffio -> (unit,char) data and ('e,'a) gen = { mutable curr : 'a option option; func : 'e -> 'a option } and buffio =
{ ic : in_channel; buff : bytes; mutable len : int; mutable ind : int }
exception Failure
let count { count } = count
let fill_buff b =
b.len <- input b.ic b.buff 0 (Bytes.length b.buff); b.ind <- 0
let peek : type e v. e -> (e,v) t -> v option = fun e s -> (* consult the first item of s *) match s.data with
Sempty -> None
| Scons (a, _) -> Some a
| Sgen {curr = Some a} -> a
| Sgen g -> let x = g.func e in g.curr <- Some x; x
| Sbuffio b -> if b.ind >= b.len then fill_buff b; if b.len == 0 thenbegin s.data <- Sempty; None end else Some (Bytes.unsafe_get b.buff b.ind)
let rec junk : type e v. e -> (e,v) t -> unit = fun e s -> match s.data with
Scons (_, d) -> s.count <- (succ s.count); s.data <- d
| Sgen ({curr = Some _} as g) -> s.count <- (succ s.count); g.curr <- None
| Sbuffio b -> if b.ind >= b.len then fill_buff b; if b.len == 0 then s.data <- Sempty else (s.count <- (succ s.count); b.ind <- succ b.ind)
| Sempty -> ()
| Sgen { curr = None } -> match peek e s with
None -> ()
| Some _ -> junk e s
let rec nget e n s = if n <= 0 then [], s.data, 0 else match peek e s with
Some a ->
junk e s; let (al, d, k) = nget e (pred n) s in a :: al, Scons (a, d), succ k
| None -> [], s.data, 0
let npeek e n s = let (al, d, len) = nget e n s in
s.count <- (s.count - len);
s.data <- d;
al
let nth e n st = tryList.nth (npeek e (n+1) st) n with Stdlib.Failure _ -> raise Failure
let rec njunk e n st = if n <> 0 then (junk e st; njunk e (n-1) st)
let next e s = match peek e s with
Some a -> junk e s; a
| None -> raise Failure
let is_empty e s = match peek e s with
| Some _ -> false
| None -> true
(* Stream building functions *)
let from ?(offset=0) f = {count = offset; data = Sgen {curr = None; func = f}}
(* NB we need the thunk for value restriction *) let empty () = {count = 0; data = Sempty}
let of_string ?(offset=0) s = let count = ref 0 in
from ~offset (fun () -> let c = !count in if c < String.length s then (incr count; Some s.[c]) else None)
let of_channel ic =
{count = 0;
data = Sbuffio {ic = ic; buff = Bytes.create 4096; len = 0; ind = 0}}
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