Multimap

public struct Multimap<Key: Hashable, Value: Equatable>

A Multimap is a special kind of dictionary in which each key may be associated with multiple values. This implementation allows duplicate key-value pairs.

Comforms to Sequence, ExpressibleByDictionaryLiteral, Equatable and CustomStringConvertible

Creating a Multimap

  • Returns an array containing the values associated with the specified key. An empty array is returned if the key does not exist in the multimap.

    Declaration

    Swift

    public subscript(key: Key) -> [Value]

  • Constructs an empty multimap.

    Declaration

    Swift

    public init()

  • Constructs a multimap from a dictionary.

    Declaration

    Swift

    public init(_ elements: Dictionary<Key, Value>)

Querying a Multimap

  • Number of key-value pairs stored in the multimap.

    Declaration

    Swift

    public fileprivate(set) var count = 0

  • Number of distinct keys stored in the multimap.

    Declaration

    Swift

    public var keyCount: Int

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

    Declaration

    Swift

    public var isEmpty: Bool

  • A sequence containing the multimap’s unique keys.

    Declaration

    Swift

    public var keys: AnySequence<Key>

  • A sequence containing the multimap’s values.

    Declaration

    Swift

    public var values: AnySequence<Value>

  • Returns true if the multimap contains at least one key-value pair with the given key.

    Declaration

    Swift

    public mutating func containsKey(_ key: Key) -> Bool

  • Returns true if the multimap contains at least one key-value pair with the given key and value.

    Declaration

    Swift

    public func containsValue(_ value: Value, forKey key: Key) -> Bool

Accessing and Changing Multimap Elements

  • Inserts a key-value pair into the multimap.

    Declaration

    Swift

    public mutating func insertValue(_ value: Value, forKey key: Key)

  • Inserts multiple key-value pairs into the multimap.

    Declaration

    Swift

    public mutating func insertValues<S:Sequence>(_ values: S, forKey key: Key) where S.Iterator.Element == Value

    Parameters

    values

    A sequence of values to associate with the given key

  • Replaces all the values associated with a given key. If the key does not exist in the multimap, the values are inserted.

    Declaration

    Swift

    public mutating func replaceValues<S:Sequence>(_ values: S, forKey key: Key) where S.Iterator.Element == Value

    Parameters

    values

    A sequence of values to associate with the given key

  • Removes a single key-value pair with the given key and value from the multimap, if it exists.

    Declaration

    Swift

    public mutating func removeValue(_ value: Value, forKey key: Key) -> Value?

    Return Value

    The removed value, or nil if no matching pair is found.

  • Removes all values associated with the given key.

    Declaration

    Swift

    public mutating func removeValuesForKey(_ key: Key)

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

    Declaration

    Swift

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

SequenceType Protocol Conformance

  • Provides for-in loop functionality.

    Declaration

    Swift

    public func makeIterator() -> AnyIterator<(Key,Value)>

    Return Value

    A generator over the elements.

DictionaryLiteralConvertible Protocol Conformance

  • Constructs a multiset using a dictionary literal. Unlike a set, multiple copies of an element are inserted.

    Declaration

    Swift

    public init(dictionaryLiteral elements: (Key, Value)...)

CustomStringConvertible Protocol Conformance

  • A string containing a suitable textual representation of the multimap.

    Declaration

    Swift

    public var description: String

Multimap Equatable Conformance

  • Returns true if and only if the multimaps contain the same key-value pairs.

    Declaration

    Swift

    public static func ==<Key, Value>(lhs: Multimap<Key, Value>, rhs: Multimap<Key, Value>) -> Bool