PriorityQueue

public struct PriorityQueue<T>

In a priority queue each element is associated with a priority, elements are dequeued in highest-priority-first order (the elements with the highest priority are dequeued first).

The enqueue and dequeue operations run in O(log(n)) time.

Conforms to Sequence, CustomStringConvertible.

Creating a Priority Queue

  • Constructs an empty priority queue using a closure to determine the order of a provided pair of elements. The closure that you supply for sortedBy should return a boolean value to indicate whether one element should be before (true) or after (false) another element using strict weak ordering. See http://en.wikipedia.org/wiki/Weak_ordering#Strict_weak_orderings

    Declaration

    Swift

    public init(sortedBy sortFunction: @escaping (T,T) -> Bool)

    Parameters

    sortedBy

    Strict weak ordering function checking if the first element has higher priority.

  • Constructs a priority queue from a sequence, such as an array, using a given closure to determine the order of a provided pair of elements. The closure that you supply for sortedBy should return a boolean value to indicate whether one element should be before (true) or after (false) another element using strict weak ordering. See http://en.wikipedia.org/wiki/Weak_ordering#Strict_weak_orderings

    Declaration

    Swift

    public init<S: Sequence>(_ elements: S, sortedBy sortFunction: @escaping (T,T) -> Bool) where S.Iterator.Element == T

    Parameters

    sortedBy

    Strict weak ordering function for checking if the first element has higher priority.

Querying a Priority Queue

  • Number of elements stored in the priority queue.

    Declaration

    Swift

    public var count: Int

  • Returns true if and only if count == 0.

    Declaration

    Swift

    public var isEmpty: Bool

  • The highest priority element in the queue, or nil if the queue is empty.

    Declaration

    Swift

    public var first: T?

Adding and Removing Elements

  • Inserts an element into the priority queue.

    Declaration

    Swift

    public mutating func enqueue(_ element: T)

  • Retrieves and removes the highest priority element of the queue.

    Declaration

    Swift

    public mutating func dequeue() -> T

    Return Value

    The highest priority element, or nil if the queue is empty.

  • Removes all the elements from the priority queue, and by default clears the underlying storage buffer.

    Declaration

    Swift

    public mutating func removeAll(keepingCapacity keep: Bool = false)

Sequence Protocol Conformance

  • Provides for-in loop functionality. Generates elements in no particular order.

    Declaration

    Swift

    public func makeIterator() -> AnyIterator<T>

    Return Value

    A generator over the elements.

CustomStringConvertible Protocol Conformance

  • A string containing a suitable textual representation of the priority queue.

    Declaration

    Swift

    public var description: String