# Module Dllist

    module Dllist: sig .. end

A mutable, imperative, circular, doubly linked list library

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

node functions

    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.

list conversion

    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.

enums

    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.