linkedlist.lua

• Index

Contents

• Methods additional to the Single linked list interface
• Single linked list interface

Classes

• linkedlist.double
• linkedlist.single

Topics

• README

Class linkedlist.double

A double-linked-list class.

The class features the following functionality:

• API compatible with the single-linked-list (easy to switch)
• adds lifo queue behaviour.
• adds method to swap 2 items in position
• adds methods for moving items up/down
• adds a reverse iterator

The item objects are mostly for internal use only. The actual value stored lives in the item.value field.

Methods additional to the Single linked list interface

Single linked list interface

Methods additional to the Single linked list interface

List:get_previous ([item])

Gets the previous item.

Parameters:

• item item an item object as returned when added, if not provided, the last item in the list will be returned. (optional)

Returns:

the previous/last item, or nil+"not found"

List:move_down (item)

Moves an item 1 element down. Moves 1 position towards the end of the list. Does nothing if the item is already at the end of the list.

Parameters:

• item item must be an item object as returned when added.

Returns:

true if successful, false if already at the end

List:move_up (item)

Moves an item 1 element up. Moves 1 position towards the start of the list. Does nothing if the item is already at the top of the list.

Parameters:

• item item must be an item object as returned when added.

Returns:

true if successful, false if already at the top

List:peek_lifo ()

Returns the value at the end (lifo), without removing it.

Returns:

the value at the end, or nil+"not found" if empty

List:pop_lifo ()

Pops the value at the end (lifo).

Returns:

the value at the end, or nil+"not found" if empty

List:reverse_iter ()

Iterator over the list, in reverse order. Note: the returned count will be from 1 to size, ascending.

Returns:

iterator returning count and value

Usage:

for cnt, value in my_list:iter() do
    print(value)
end

List:swap (item1, item2)

Swaps two items. Updates the positions of the two items in the list. If the items are the same item, nothing happens.

Parameters:

• item1 item must be an item object as returned when added.
• item2 item must be an item object as returned when added.

Returns:

nothing

Single linked list interface

List.new ()

Create a new Linked List object.

Returns:

Linked List object

Usage:

local lst = List.new()
-- or alternatively
local lst = List()

List:add_value (value[, idx=size+1])

Adds an item to the list. Note that the idx position, is the position where the item ends up after insertion. Too high or too low indices will not return errors, but insert at the start/end.

Parameters:

• value the value to store in the list, can be any type, inlcuding nil
• idx int position where to add (negative indices allowed, idx = 0 will add at the start). By default appends at end. (default size+1)

Returns:

the added item.

List:clear ()

Clears the list.

Returns:

true

List:first_item ()

Gets the first item in the list. Does not remove the item from the list.

Returns:

the first item, or nil+"not found"

List:first_value ()

Gets the first value in the list. Does not remove the value from the list.

Returns:

the first value, or nil+"not found"

List:get_item (idx)

Gets the item at the specified index. Note: this method iterates over the list to find the index, so it is not efficient, especially with larger lists.

Parameters:

• idx int index of the item to return

Returns:

the item, or nil+"not found"

List:get_next ([item])

Gets the next item.

Parameters:

• item item an item object as returned when added, if not provided, the first item in the list will be returned. (optional)

Returns:

the next/first item, or nil+"not found"

List:get_size ()

Gets the length of the list.

Returns:

integer, length of the list

List:get_value (idx)

Gets the value at the specified index. Note: this method iterates over the list to find the index, so it is not efficient, especially with larger lists.

Parameters:

• idx int index of the value to return

Returns:

the value, or nil+"not found"

List:iter ()

Iterator over the list.

Returns:

iterator returning idx and value

Usage:

for i, value in my_list:iter() do
    print(value)
end

List:last_item ()

Gets the last item in the list. Does not remove the item from the list.

Returns:

the last item

List:last_value ()

Gets the last value in the list. Does not remove the value from the list.

Returns:

the last value

List:peek ()

Returns the value at the top/start, without removing it.

Returns:

the value at the start, or nil+"not found" if empty

List:pop ()

Pops the value at the top/start.

Returns:

the value at the start, or nil+"not found" if empty

List:push (value)

Adds a value to the end of the list.

Parameters:

• value the value to store in the list, can be any type, inlcuding nil

Returns:

the added item.