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(* arch-tag: slices of sequences of things
Copyright (C) 2004 John Goerzen <jgoerzen@complete.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*)
type slice_finish_t = EndOfList | EndingOffset of int | Position of int;;
type slice_t = (int * slice_finish_t);;
let slice_end = max_int;;
let slice_of_pair (pair:int * int) =
let x = fst pair and y = snd pair in
(x, if y < 0 then
(EndingOffset (-y))
else (if y = slice_end then
(EndOfList)
else
(Position y)));;
let subvalues_of_slice (s:slice_t) len =
let start = fst s and
finish = match snd s with
EndOfList -> len
| EndingOffset x -> len - x
| Position x -> x in
if (start < 0) then (raise (Invalid_argument "Slice.subvalues_of_slice"));
if (finish > len) || (finish < 0) || (finish < start) then
(raise (Invalid_argument "Slice.subvalues_of_slice"));
if start = finish then (0, 0) else
(start, (finish - start));;
let generic_slice subfunc lenfunc item (slice:slice_t) =
let subv = subvalues_of_slice slice (lenfunc item) in
subfunc item (fst subv) (snd subv);;
let string_slice = generic_slice String.sub String.length;;
let array_slice item s = generic_slice Array.sub Array.length item s;;
let list_slice item s = generic_slice Listutil.sub List.length item s;;
|
