Generic Structure

FlattenCollection

A flattened view of a base collection of collections.

Declaration

struct FlattenCollection<Base> where Base : Collection, Base.Element : Collection

Overview

The elements of this view are a concatenation of the elements of each collection in the base.

The joined method is always lazy, but does not implicitly confer laziness on algorithms applied to its result. In other words, for ordinary collections c:

  • c.joined() does not create new storage

  • c.joined().map(f) maps eagerly and returns a new array

  • c.lazy.joined().map(f) maps lazily and returns a LazyMapCollection

  • See also: FlattenSequence

Topics

Initializers

init(Base)

Creates a flattened view of base.

Instance Properties

var count: Int

The number of elements in the collection.

var endIndex: FlattenCollection<Base>.Index

The collection’s “past the end” position.

var first: Base.Element.Element?

The first element of the collection.

var indices: DefaultIndices<FlattenCollection<Base>>

The indices that are valid for subscripting the collection, in ascending order.

var isEmpty: Bool

A Boolean value indicating whether the collection is empty.

var last: Base.Element.Element?

The last element of the collection.

var lazy: LazyCollection<FlattenCollection<Base>>

A view onto this collection that provides lazy implementations of normally eager operations, such as map and filter.

var lazy: LazySequence<FlattenCollection<Base>>

A sequence containing the same elements as this sequence, but on which some operations, such as map and filter, are implemented lazily.

var startIndex: FlattenCollection<Base>.Index

The position of the first element in a non-empty collection.

var underestimatedCount: Int

A value less than or equal to the number of elements in the sequence, calculated nondestructively.

var underestimatedCount: Int

A value less than or equal to the number of elements in the collection.

Instance Methods

func allSatisfy((Base.Element.Element) -> Bool) -> Bool

Returns a Boolean value indicating whether every element of a sequence satisfies a given predicate.

func compactMap<ElementOfResult>((Base.Element.Element) -> ElementOfResult?) -> [ElementOfResult]

Returns an array containing the non-nil results of calling the given transformation with each element of this sequence.

func contains(Base.Element.Element) -> Bool

Returns a Boolean value indicating whether the sequence contains the given element.

func contains(where: (Base.Element.Element) -> Bool) -> Bool

Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.

func drop(while: (Base.Element.Element) -> Bool) -> Slice<FlattenCollection<Base>>

Returns a subsequence by skipping elements while predicate returns true and returning the remaining elements.

func dropFirst() -> Slice<FlattenCollection<Base>>

Returns a subsequence containing all but the first element of the sequence.

func dropFirst(Int) -> Slice<FlattenCollection<Base>>

Returns a subsequence containing all but the given number of initial elements.

func dropLast() -> Slice<FlattenCollection<Base>>

Returns a subsequence containing all but the last element of the sequence.

func dropLast(Int) -> Slice<FlattenCollection<Base>>

Returns a subsequence containing all but the specified number of final elements.

func elementsEqual<OtherSequence>(OtherSequence) -> Bool

Returns a Boolean value indicating whether this sequence and another sequence contain the same elements in the same order.

func elementsEqual<OtherSequence>(OtherSequence, by: (Base.Element.Element, OtherSequence.Element) -> Bool) -> Bool

Returns a Boolean value indicating whether this sequence and another sequence contain equivalent elements in the same order, using the given predicate as the equivalence test.

func enumerated() -> EnumeratedSequence<FlattenCollection<Base>>

Returns a sequence of pairs (n, x), where n represents a consecutive integer starting at zero and x represents an element of the sequence.

func filter((Base.Element.Element) -> Bool) -> [Base.Element.Element]

Returns an array containing, in order, the elements of the sequence that satisfy the given predicate.

func first(where: (Base.Element.Element) -> Bool) -> Base.Element.Element?

Returns the first element of the sequence that satisfies the given predicate.

func firstIndex(of: Base.Element.Element) -> FlattenCollection<Base>.Index?

Returns the first index where the specified value appears in the collection.

func firstIndex(where: (Base.Element.Element) -> Bool) -> FlattenCollection<Base>.Index?

Returns the first index in which an element of the collection satisfies the given predicate.

func formIndex(before: inout FlattenCollection<Base>.Index)
func index(before: FlattenCollection<Base>.Index) -> FlattenCollection<Base>.Index
func joined() -> FlattenSequence<FlattenCollection<Base>>

Returns the elements of this sequence of sequences, concatenated.

func joined() -> FlattenCollection<FlattenCollection<Base>>

Returns the elements of this collection of collections, concatenated.

func joined<Separator>(separator: Separator) -> JoinedSequence<FlattenCollection<Base>>

Returns the concatenated elements of this sequence of sequences, inserting the given separator between each element.

func joined(separator: String) -> String

Returns a new string by concatenating the elements of the sequence, adding the given separator between each element.

func joined(separator: String) -> String

Returns a new string by concatenating the elements of the sequence, adding the given separator between each element.

func last(where: (Base.Element.Element) -> Bool) -> Base.Element.Element?

Returns the last element of the sequence that satisfies the given predicate.

func lastIndex(of: Base.Element.Element) -> FlattenCollection<Base>.Index?

Returns the last index where the specified value appears in the collection.

func lastIndex(where: (Base.Element.Element) -> Bool) -> FlattenCollection<Base>.Index?

Returns the index of the last element in the collection that matches the given predicate.

func lexicographicallyPrecedes<OtherSequence>(OtherSequence) -> Bool

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the less-than operator (<) to compare elements.

func lexicographicallyPrecedes<OtherSequence>(OtherSequence, by: (Base.Element.Element, Base.Element.Element) -> Bool) -> Bool

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.

func makeIterator() -> FlattenCollection<Base>.Iterator

Returns an iterator over the elements of this sequence.

func map<T>((Base.Element.Element) -> T) -> [T]

Returns an array containing the results of mapping the given closure over the sequence’s elements.

func map<T>((Base.Element.Element) -> T) -> [T]

Returns an array containing the results of mapping the given closure over the sequence’s elements.

func max() -> Base.Element.Element?

Returns the maximum element in the sequence.

func max(by: (Base.Element.Element, Base.Element.Element) -> Bool) -> Base.Element.Element?

Returns the maximum element in the sequence, using the given predicate as the comparison between elements.

func min() -> Base.Element.Element?

Returns the minimum element in the sequence.

func min(by: (Base.Element.Element, Base.Element.Element) -> Bool) -> Base.Element.Element?

Returns the minimum element in the sequence, using the given predicate as the comparison between elements.

func prefix(Int) -> Slice<FlattenCollection<Base>>

Returns a subsequence, up to the specified maximum length, containing the initial elements of the collection.

func prefix(through: FlattenCollection<Base>.Index) -> Slice<FlattenCollection<Base>>

Returns a subsequence from the start of the collection through the specified position.

func prefix(upTo: FlattenCollection<Base>.Index) -> Slice<FlattenCollection<Base>>

Returns a subsequence from the start of the collection up to, but not including, the specified position.

func prefix(while: (Base.Element.Element) -> Bool) -> Slice<FlattenCollection<Base>>

Returns a subsequence containing the initial elements until predicate returns false and skipping the remaining elements.

func randomElement() -> Base.Element.Element?

Returns a random element of the collection.

func randomElement<T>(using: inout T) -> Base.Element.Element?

Returns a random element of the collection, using the given generator as a source for randomness.

func reduce<Result>(Result, (Result, Base.Element.Element) -> Result) -> Result

Returns the result of combining the elements of the sequence using the given closure.

func reduce<Result>(into: Result, (inout Result, Base.Element.Element) -> ()) -> Result

Returns the result of combining the elements of the sequence using the given closure.

func reversed() -> [Base.Element.Element]

Returns an array containing the elements of this sequence in reverse order.

func shuffled() -> [Base.Element.Element]

Returns the elements of the sequence, shuffled.

func shuffled<T>(using: inout T) -> [Base.Element.Element]

Returns the elements of the sequence, shuffled using the given generator as a source for randomness.

func sorted() -> [Base.Element.Element]

Returns the elements of the sequence, sorted.

func sorted(by: (Base.Element.Element, Base.Element.Element) -> Bool) -> [Base.Element.Element]

Returns the elements of the sequence, sorted using the given predicate as the comparison between elements.

func split(maxSplits: Int, omittingEmptySubsequences: Bool, whereSeparator: (Base.Element.Element) -> Bool) -> [Slice<FlattenCollection<Base>>]

Returns the longest possible subsequences of the collection, in order, that don’t contain elements satisfying the given predicate.

func split(separator: Base.Element.Element, maxSplits: Int, omittingEmptySubsequences: Bool) -> [Slice<FlattenCollection<Base>>]

Returns the longest possible subsequences of the sequence, in order, around elements equal to the given element.

func split(separator: Base.Element.Element, maxSplits: Int, omittingEmptySubsequences: Bool) -> [Slice<FlattenCollection<Base>>]

Returns the longest possible subsequences of the collection, in order, around elements equal to the given element.

func starts<PossiblePrefix>(with: PossiblePrefix) -> Bool

Returns a Boolean value indicating whether the initial elements of the sequence are the same as the elements in another sequence.

func starts<PossiblePrefix>(with: PossiblePrefix, by: (Base.Element.Element, PossiblePrefix.Element) -> Bool) -> Bool

Returns a Boolean value indicating whether the initial elements of the sequence are equivalent to the elements in another sequence, using the given predicate as the equivalence test.

func suffix(Int) -> Slice<FlattenCollection<Base>>

Returns a subsequence, up to the given maximum length, containing the final elements of the collection.

func suffix(from: FlattenCollection<Base>.Index) -> Slice<FlattenCollection<Base>>

Returns a subsequence from the specified position to the end of the collection.

Structures

struct FlattenCollection.Index

A position in a FlattenCollection

Relationships

Conforms To

See Also

Wrappers for Algorithms

struct EnumeratedSequence

An enumeration of the elements of a sequence or collection.

struct FlattenSequence

A sequence consisting of all the elements contained in each segment contained in some Base sequence.

struct JoinedSequence

A sequence that presents the elements of a base sequence of sequences concatenated using a given separator.

struct Repeated

A collection whose elements are all identical.

struct ReversedCollection

A collection that presents the elements of its base collection in reverse order.

struct StrideTo

A sequence of values formed by striding over a half-open interval.

struct StrideThrough

A sequence of values formed by striding over a closed interval.

struct UnfoldSequence

A sequence whose elements are produced via repeated applications of a closure to some mutable state.

struct Zip2Sequence

A sequence of pairs built out of two underlying sequences.