(***********************************************************************) (* *) (* OCaml library from the book ``Apprendre à programmer avec OCaml'' *) (* *) (* Sylvain Conchon and Jean-Christophe Filliâtre *) (* Université Paris Sud *) (* *) (* Copyright 2014 Université Paris Sud. All rights reserved. This *) (* file is distributed under the terms of the GNU Library General *) (* Public License, with the same special exception on linking as the *) (* OCaml library. See http://caml.inria.fr/ocaml/license.fr.html *) (* *) (***********************************************************************) (* Programme 73 page 308 Structure de zipper pour une liste *) type 'a zipper = { left: 'a list; right: 'a list; } let of_list l = { left = []; right = l } let move_right z = match z.right with | [] -> invalid_arg "move_right" | x :: r -> { left = x :: z.left; right = r } let move_left z = match z.left with | [] -> invalid_arg "move_left" | x :: l -> { left = l; right = x :: z.right } let to_list z = List.rev_append z.left z.right let insert z x = { z with left = x :: z.left } let delete_left z = match z.left with | [] -> invalid_arg "delete_left" | _ :: l -> { z with left = l } let delete_right z = match z.right with | [] -> invalid_arg "delete_right" | _ :: r -> { z with right = r }