BitArray

public struct BitArray

An array of boolean values stored using individual bits, thus providing a very small memory footprint. It has most of the features of a standard array such as constant time random access and amortized constant time insertion at the end of the array.

Conforms to MutableCollection, ExpressibleByArrayLiteral , Equatable, Hashable, CustomStringConvertible

Creating a BitArray

  • Constructs an empty bit array.

    Declaration

    Swift

    public init()

  • Constructs a bit array from a Bool sequence, such as an array.

    Declaration

    Swift

    public init<S: Sequence>(_ elements: S) where S.Iterator.Element == Bool

  • Constructs a new bit array from an Int array representation. All values different from 0 are considered true.

    Declaration

    Swift

    public init(intRepresentation : [Int])

  • Constructs a new bit array with count bits set to the specified value.

    Declaration

    Swift

    public init(repeating repeatedValue: Bool, count: Int)

Querying a BitArray

  • Number of bits stored in the bit array.

    Declaration

    Swift

    public fileprivate(set) var count = 0

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

    Declaration

    Swift

    public var isEmpty: Bool

  • The first bit, or nil if the bit array is empty.

    Declaration

    Swift

    public var first: Bool?

  • The last bit, or nil if the bit array is empty.

    Declaration

    Swift

    public var last: Bool?

  • The number of bits set to true in the bit array.

    Declaration

    Swift

    public fileprivate(set) var cardinality = 0

Adding and Removing Bits

  • Adds a new Bool as the last bit.

    Declaration

    Swift

    public mutating func append(_ bit: Bool)

  • Inserts a bit into the array at a given index. Use this method to insert a new bit anywhere within the range of existing bits, or as the last bit. The index must be less than or equal to the number of bits in the bit array. If you attempt to remove a bit at a greater index, you’ll trigger an error.

    Declaration

    Swift

    public mutating func insert(_ bit: Bool, at index: Int)

  • Removes the last bit from the bit array and returns it.

    Declaration

    Swift

    public mutating func removeLast() -> Bool

    Return Value

    The last bit, or nil if the bit array is empty.

  • Removes the bit at the given index and returns it. The index must be less than the number of bits in the bit array. If you attempt to remove a bit at a greater index, you’ll trigger an error.

    Declaration

    Swift

    public mutating func remove(at index: Int) -> Bool

  • Removes all the bits from the array, and by default clears the underlying storage buffer.

    Declaration

    Swift

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

MutableCollection Protocol Conformance

  • Provides random access to individual bits using square bracket noation. The index must be less than the number of items in the bit array. If you attempt to get or set a bit at a greater index, you’ll trigger an error.

    Declaration

    Swift

    public subscript(index: Int) -> Bool

  • Always zero, which is the index of the first bit when non-empty.

    Declaration

    Swift

    public var startIndex : Int

  • Always count, which the successor of the last valid subscript argument.

    Declaration

    Swift

    public var endIndex : Int

  • Returns the position immediately after the given index.

    Parameter

    Parameter i: A valid index of the collection. i must be less than endIndex.

    Returns

    The index value immediately after i.

    Declaration

    Swift

    public func index(after i: Int) -> Int

    Parameters

    i

    A valid index of the collection. i must be less than endIndex.

    Return Value

    The index value immediately after i.

ExpressibleByArrayLiteral Protocol Conformance

  • Constructs a bit array using a Bool array literal. let example: BitArray = [true, false, true]

    Declaration

    Swift

    public init(arrayLiteral elements: Bool...)

CustomStringConvertible Protocol Conformance

  • A string containing a suitable textual representation of the bit array.

    Declaration

    Swift

    public var description: String

Hashable Protocol Conformance

  • The hash value. x == y implies x.hashValue == y.hashValue

    Declaration

    Swift

    public var hashValue: Int