HTMLPurifier_Queue
in package
A simple array-backed queue, based off of the classic Okasaki persistent amortized queue. The basic idea is to maintain two stacks: an input stack and an output stack. When the output stack runs out, reverse the input stack and use it as the output stack.
We don't use the SPL implementation because it's only supported on PHP 5.3 and later.
Exercise: Prove that push/pop on this queue take amortized O(1) time.
Exercise: Extend this queue to be a deque, while preserving amortized O(1) time. Some care must be taken on rebalancing to avoid quadratic behaviour caused by repeatedly shuffling data from the input stack to the output stack and back.
Table of Contents
Properties
Methods
- __construct() : mixed
- isEmpty() : mixed
- Checks if it's empty.
- push() : mixed
- Pushes an element onto the front of the queue.
- shift() : mixed
- Shifts an element off the front of the queue.
Properties
$input
private
mixed
$input
$output
private
mixed
$output
Methods
__construct()
public
__construct([mixed $input = array() ]) : mixed
Parameters
- $input : mixed = array()
isEmpty()
Checks if it's empty.
public
isEmpty() : mixed
push()
Pushes an element onto the front of the queue.
public
push(mixed $x) : mixed
Parameters
- $x : mixed
shift()
Shifts an element off the front of the queue.
public
shift() : mixed