module Dllist:A mutable, imperative, circular, doubly linked list library`sig`

..`end`

This module implements a doubly linked list in a mutable or imperitive
style (changes to the list are visible to all copies of the list).

`type ``'a`

node_t

`exception Empty`

`val create : ``'a -> 'a node_t`

Creates a node. This is an O(1) operation.

`val copy : ``'a node_t -> 'a node_t`

Copy the list attached to the given node and return the copy of the given
node. This is an O(N) operation.

`val length : ``'a node_t -> int`

Returns the length of the list. This is an O(N) operation.

`val rev : ``'a node_t -> unit`

List reversal. This is an O(N) operation.

`val add : ``'a node_t -> 'a -> unit`

`add n a`

Creates a new node containing data `a`

and inserts it into
the list after node `n`

. This is an O(1) operation.`val append : ``'a node_t -> 'a -> 'a node_t`

`append n a`

Creates a new node containing data `a`

and inserts it into
the list after node `n`

. Returns new node. This is an O(1) operation.`val prepend : ``'a node_t -> 'a -> 'a node_t`

`prepend n a`

Creates a new node containing data `a`

and inserts it into
the list before node `n`

. Returns new node. This is an O(1) operation.`val promote : ``'a node_t -> unit`

`promote n`

Swaps `n`

with `next n`

. This is an O(1) operation.`val demote : ``'a node_t -> unit`

`demote n`

Swaps `n`

with `prev n`

. This is an O(1) operation.`val remove : ``'a node_t -> unit`

Remove node from the list no matter where it is. This is an O(1) operation.

`val drop : ``'a node_t -> 'a node_t`

Remove node from the list no matter where it is. Return next node. This is
an O(1) operation.

`val rev_drop : ``'a node_t -> 'a node_t`

Remove node from the list no matter where it is. Return previous node. This
is an O(1) operation.

`val splice : ``'a node_t -> 'a node_t -> unit`

`splice n1 n2`

Connects `n1`

and `n2`

so that
`next n1 == n2 && prev n2 == n1`

. This can be used to connect two discrete
lists, or, if used on two nodes within the same list, it can be used to
separate the nodes between `n1`

and `n2`

from the rest of the list. In this
case, those nodes become a discrete list by themselves. This is an O(1)
operation.`val get : ``'a node_t -> 'a`

Given a node, get the data associated with that node. This is an
O(1) operation.

`val set : ``'a node_t -> 'a -> unit`

Given a node, set the data associated with that node. This is an O(1)
operation.

`val next : ``'a node_t -> 'a node_t`

Given a node, get the next element in the list after the node.

The list is circular, so the last node of the list returns the first node of the list as it's next node.

This is an O(1) operation.

`val prev : ``'a node_t -> 'a node_t`

Given a node, get the previous element in the list before the node.

The list is circular, so the first node of the list returns the last element of the list as it's previous node.

This is an O(1) operation.

`val skip : ``'a node_t -> int -> 'a node_t`

`skip n i`

Return the node that is `i`

nodes after node `n`

in the list.
If `i`

is negative then return the node that is `i`

nodes before node `n`

in the list. This is an O(N) operation.`val iter : ``('a -> unit) -> 'a node_t -> unit`

`iter f n`

Apply `f`

to every element in the list, starting at `n`

. This
is an O(N) operation.`val fold_left : ``('a -> 'b -> 'a) -> 'a -> 'b node_t -> 'a`

Accumulate a value over the entire list.
This works like List.fold_left. This is an O(N) operation.

`val fold_right : ``('a -> 'b -> 'b) -> 'a node_t -> 'b -> 'b`

Accumulate a value over the entire list.
This works like List.fold_right, but since the list is bidirectional,
it doesn't suffer the performance problems of List.fold_right.
This is an O(N) operation.

`val map : ``('a -> 'b) -> 'a node_t -> 'b node_t`

Allocate a new list, with entirely new nodes, whose values are
the transforms of the values of the original list. Note that this
does not modify the given list. This is an O(N) operation.

`val to_list : ``'a node_t -> 'a list`

Converts a dllist to a normal list. This is an O(N) operation.

`val of_list : ``'a list -> 'a node_t`

Converts from a normal list to a Dllist and returns the first node. Raises

`Empty`

if given list is empty. This is an O(N) operation.`val enum : ``'a node_t -> 'a Enum.t`

Create an enum of the list.
Note that modifying the list while the enum exists will have undefined
effects. This is an O(1) operation.

`val rev_enum : ``'a node_t -> 'a Enum.t`

Create a reverse enum of the list.
Note that modifying the list while the enum exists will have undefined
effects. This is an O(1) operation.

`val of_enum : ``'a Enum.t -> 'a node_t`

Create a dllist from an enum.
This consumes the enum, and allocates a whole new dllist. Raises

`Empty`

if given enum is empty. This is an O(N) operation.