Queue module

A double queue.

Taken from Programming in Lua Queues and Double Queues and modified to not allow nil values, and returns nil if pop_first or pop_last is used when the queue is empty.

Usage

local Queue = require('stdlib/queue/queue')

Functions

count (queue)	Returns the number of items in the queue.
is_empty (queue)	Returns true if the given queue is empty.
load (...)	Load global.queue or queues during on_load, as metatables are not persisted.
new ()	Constructs a new Queue object.
peek ()	Shortcut for Queue.peek_first
peek_first (queue)	Return the element at the front of the queue and remove it from the queue.
peek_last (queue)	Return the element at the back of the queue.
pop ()	Shortcut for Queue.pop_first
pop_first (queue)	Retrieve the element at the front of the queue and remove it from the queue.
pop_last (queue)	Retrieve the element at the back of the queue and remove it from the queue.
push ()	Shortcut for Queue.push_last
push_first (queue, value)	Push a new element to the front of the queue.
push_last (queue, value)	Push a new element to the back of the queue.

Functions

# count (queue)

Returns the number of items in the queue.

Parameters:

• queue : (Queue) the queue to check

Returns:

• (number) the number of items in the queue

# is_empty (queue)

Returns true if the given queue is empty.

Parameters:

• queue : (Queue) the queue to check

Returns:

• (boolean) true if empty, false otherwise

# load (...)

Load global.queue or queues during on_load, as metatables are not persisted.

This is only needed if you are using the queue as an object and storing it in global.

Parameters:

• ... : (Queue,...)

Usage:

global.myqueue1 = Queue.new()
global.myqueue2 = Queue.new()
script.on_load(function() Queue.load(myqueue1, myqueue2))

# new ()

Constructs a new Queue object.

Returns:

• (Queue) a new, empty queue

# peek ()

Shortcut for Queue.peek_first

# peek_first (queue)

Return the element at the front of the queue and remove it from the queue.

Parameters:

• queue : (Queue) the queue to retrieve the element from

Returns:

• (Mixed) the element at the front of the queue

# peek_last (queue)

Return the element at the back of the queue.

Parameters:

• queue : (Queue) the queue to retrieve the element from

Returns:

• (Mixed) the element at the back of the queue

# pop ()

Shortcut for Queue.pop_first

# pop_first (queue)

Retrieve the element at the front of the queue and remove it from the queue.

Parameters:

• queue : (Queue) the queue to retrieve the element from

Returns:

• (Mixed) value the element at the front of the queue

# pop_last (queue)

Retrieve the element at the back of the queue and remove it from the queue.

Parameters:

• queue : (Queue) the queue to retrieve the element from

Returns:

• (Mixed) the element at the back of the queue

# push ()

Shortcut for Queue.push_last

# push_first (queue, value)

Push a new element to the front of the queue.

Parameters:

• queue : (Queue) the queue to push an element to
• value : (Mixed) the element to push

# push_last (queue, value)

Push a new element to the back of the queue.

Parameters:

• queue : (Queue) the queue to push an element to
• value : (Mixed) the element to push