1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
open Import
type t =
{ s : string
; pos : int
; len : int
}
module L = struct
type nonrec t = t list
let get_substring slices ~start ~stop =
if stop = start
then ""
else (
let slices =
let rec drop slices remains =
if remains = 0
then slices
else (
match slices with
| [] -> assert false
| ({ s = _; pos; len } as slice) :: xs ->
let remains' = remains - len in
if remains' >= 0
then drop xs remains'
else (
let pos = pos + remains in
let len = len - remains in
{ slice with pos; len } :: xs))
in
drop slices start
in
let buf = Buffer.create (stop - start) in
let rec take slices remains =
if remains > 0
then (
match slices with
| [] -> assert false
| { s; pos; len } :: xs ->
let remains' = remains - len in
if remains' > 0
then (
Buffer.add_substring buf s pos len;
take xs remains')
else Buffer.add_substring buf s pos remains)
in
take slices (stop - start);
Buffer.contents buf)
;;
let rec drop t remains =
if remains = 0
then t
else (
match t with
| [] -> []
| ({ s = _; pos; len } as slice) :: t ->
if remains >= len
then drop t (remains - len)
else (
let delta = len - remains in
{ slice with pos = pos + delta; len = len - delta } :: t))
;;
let drop_rev t remains =
(* TODO Use a proper functional queue *)
if remains = 0 then t else List.rev (drop (List.rev t) remains)
;;
end
|
