Previous  Up  Next

Module Doubly_linked

module Doubly_linked: Doubly_linked

There is a fundamental problem with a data structure (like doubly-linked lists) that is both mutable and provides iteration function that call back to user-supplied functions. If those user-supplied functions modify the data structure, what is the semantics of the remainder of the iteration? This module sidesteps this issue by detecting attempts by user-supplied functions to modify a doubly-linked list while in the middle of iterating over it.

Modification functions include: insert_*, remove*, transfer Iteration functions include: exists, fold*, for_all, find

Calls to modification functions detect if the list is being iterated over, and if so raise an exception rather than modify the list. For example, a use like the following would raise.

iter t ~f:(fun _ -> ... remove t e ...)

module Elt: sig .. end
type 'a t 
include Container.S1
val invariant : 'a t -> unit
val create : unit -> 'a t
creating doubly-linked lists
val of_list : 'a list -> 'a t
of_list l returns a doubly-linked list t with the same elements as l and in the same order (i.e. the first element of l is the first element of t). It is always the case that l = to_list (of_list l).
val equal : 'a t -> 'a t -> bool
predicates
val is_first : 'a t -> 'a Elt.t -> bool
val is_last : 'a t -> 'a Elt.t -> bool
val first_elt : 'a t -> 'a Elt.t option
constant-time extraction of first and last elements.
val last_elt : 'a t -> 'a Elt.t option
val first : 'a t -> 'a option
val last : 'a t -> 'a option
val next : 'a t -> 'a Elt.t -> 'a Elt.t option
constant-time move to next or previous element.
val prev : 'a t -> 'a Elt.t -> 'a Elt.t option
val insert_before : 'a t -> 'a Elt.t -> 'a -> 'a Elt.t
constant-time insertion of a new element. It is an error to call insert_before t e a or insert_after t e a if e is not an element in t.
val insert_after : 'a t -> 'a Elt.t -> 'a -> 'a Elt.t
val insert_first : 'a t -> 'a -> 'a Elt.t
val insert_last : 'a t -> 'a -> 'a Elt.t
val remove : 'a t -> 'a Elt.t -> unit
constant-time removal of an element. It is an error to call remove t e when e is not in t.
val remove_first : 'a t -> 'a option
val remove_last : 'a t -> 'a option
val fold_elt : 'a t -> init:'b -> f:('b -> 'a Elt.t -> 'b) -> 'b
fold_elt t ~init ~f is the same as fold, except f is called with the 'a Elt.t's from the list instead of the contained 'a values.

Note that like other iteration functions, it is an error to mutate t inside the fold. If you'd like to call remove on any of the 'a Elt.t's, accumulate them here and do so after fold_elt returns.

val iter_elt : 'a t -> f:('a Elt.t -> unit) -> unit
val fold_right : 'a t -> init:'b -> f:('a -> 'b -> 'b) -> 'b
val find_elt : 'a t -> f:('a -> bool) -> 'a Elt.t option
find_elt t ~f finds the first element in t that satisfies f, by testing each of element of t in turn until f succeeds.
val clear : 'a t -> unit
clear t removes all elements from the list in constant time.
val copy : 'a t -> 'a t
copy t returns a copy of t.
val transfer : src:'a t -> dst:'a t -> unit
transfer ~src ~dst has the same behavior as iter src ~f:(insert_last dst); clear src except that it runs in constant time.

If s = to_list src and d = to_list dst, then after transfer ~src ~dst: to_list src = [] to_list dst = d @ s

val filter_inplace : 'a t -> f:('a -> bool) -> unit
filter_inplace t ~f removes all elements of t that don't satisfy f.
val unchecked_iter : 'a t -> f:('a -> unit) -> unit
unchecked_iter t ~f behaves like iter t ~f except that f is allowed to modify t. Adding or removing elements before the element currently being visited has no effect on the traversal. Elements added after the element currently being visited will be traversed. Elements deleted after the element currently being visited will not be traversed. Deleting the element currently visited is an error that is not detected (presumably leading to an infinite loop) .
val t_of_sexp : (Sexplib.Sexp.t -> 'a) -> Sexplib.Sexp.t -> 'a t
val sexp_of_t : ('a -> Sexplib.Sexp.t) -> 'a t -> Sexplib.Sexp.t

creating doubly-linked lists

of_list l returns a doubly-linked list t with the same elements as l and in the same order (i.e. the first element of l is the first element of t). It is always the case that l = to_list (of_list l).

predicates

constant-time extraction of first and last elements.

constant-time move to next or previous element.

constant-time insertion of a new element. It is an error to call insert_before t e a or insert_after t e a if e is not an element in t.

constant-time removal of an element. It is an error to call remove t e when e is not in t.

fold_elt t ~init ~f is the same as fold, except f is called with the 'a Elt.t's from the list instead of the contained 'a values.

Note that like other iteration functions, it is an error to mutate t inside the fold. If you'd like to call remove on any of the 'a Elt.t's, accumulate them here and do so after fold_elt returns.

find_elt t ~f finds the first element in t that satisfies f, by testing each of element of t in turn until f succeeds.

clear t removes all elements from the list in constant time.

copy t returns a copy of t.

transfer ~src ~dst has the same behavior as iter src ~f:(insert_last dst); clear src except that it runs in constant time.

If s = to_list src and d = to_list dst, then after transfer ~src ~dst: to_list src = [] to_list dst = d @ s

filter_inplace t ~f removes all elements of t that don't satisfy f.

unchecked_iter t ~f behaves like iter t ~f except that f is allowed to modify t. Adding or removing elements before the element currently being visited has no effect on the traversal. Elements added after the element currently being visited will be traversed. Elements deleted after the element currently being visited will not be traversed. Deleting the element currently visited is an error that is not detected (presumably leading to an infinite loop) .