Trait queues::IsQueue [−] [src]

pub trait IsQueue<T: Clone> {
    fn add(&mut self, val: T) -> Result<Option<T>, &str>;

    fn remove(&mut self) -> Result<T, &str>;

    fn peek(&self) -> Result<T, &str>;

    fn size(&self) -> usize;
}

Defines methods that would be expected on a queue data structure

Required Methods

Adds a new value to a queue

Parameters

  • val: Value to add to the queue

Returns

  • Ok(_): If the element add was successful.
    • Some(T): If adding an element resulted in the removal of an existing one (in the case of a circular buffer, for instance)
    • None: Adding an element did not return any value
  • Error: If the element add was unsuccessful

Errors

Attempting to add an element to a full queue that does not allow for overflow will return an error.

Removes an element from the queue and returns it

For queues with default values, removing an element will add a new default value into the queue.

Returns

  • Ok(T): The oldest element in the queue
  • Error

Errors

Returns an error if an attempt is made to remove an element from an empty queue

Peek at the head of the queue

Returns

  • Ok(T): The next element scheduled for removal from the queue
  • Error

Errors

Returns an error if an attempt is made to peek into an empty queue

Gets the size of the queue

Returns

The number of elements in the queue. Note, this includes default values when specified, which means that the size of a queue with default values should always be equal to its capacity

Implementors