A value less than or equal to the number of elements in the sequence, calculated nondestructively.
var underestimatedCount: Int { get }The default implementation returns 0. If you provide your own implementation, make sure to compute the value nondestructively.
import Swiftprotocol Sequence<Element>A type that provides sequential, iterated access to its elements.
@frozen struct IntA signed integer value type.
var underestimatedCount: Int { get }A value less than or equal to the number of elements in the sequence, calculated nondestructively.
var lazy: LazySequence<Self> { get }A sequence containing the same elements as this sequence, but on which some operations, such as map and filter, are implemented lazily.
func allSatisfy(_ predicate: (Self.Element) throws -> Bool) rethrows -> Bool Returns a Boolean value indicating whether every element of a sequence satisfies a given predicate.
func compactMap<ElementOfResult>(_ transform: (Self.Element) throws -> ElementOfResult?) rethrows -> [ElementOfResult] Returns an array containing the non-nil results of calling the given transformation with each element of this sequence.
func contains(where predicate: (Self.Element) throws -> Bool) rethrows -> Bool Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.
func count<E>(where predicate: (Self.Element) throws(E) -> Bool) throws(E) -> Int where E : Error Returns the number of elements in the sequence that satisfy the given predicate.
func drop(while predicate: (Self.Element) throws -> Bool) rethrows -> DropWhileSequence<Self> Returns a sequence by skipping the initial, consecutive elements that satisfy the given predicate.
func dropFirst(_ k: Int = 1) -> DropFirstSequence<Self> Returns a sequence containing all but the given number of initial elements.
func dropLast(_ k: Int = 1) -> [Self.Element] Returns a sequence containing all but the given number of final elements.
func elementsEqual<OtherSequence>(_ other: OtherSequence, by areEquivalent: (Self.Element, OtherSequence.Element) throws -> Bool) rethrows -> Bool where OtherSequence : Sequence 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<Self> 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(_ isIncluded: (Self.Element) throws -> Bool) rethrows -> [Self.Element] Returns an array containing, in order, the elements of the sequence that satisfy the given predicate.
func first(where predicate: (Self.Element) throws -> Bool) rethrows -> Self.Element? Returns the first element of the sequence that satisfies the given predicate.
func flatMap<SegmentOfResult>(_ transform: (Self.Element) throws -> SegmentOfResult) rethrows -> [SegmentOfResult.Element] where SegmentOfResult : Sequence Returns an array containing the concatenated results of calling the given transformation with each element of this sequence.
func forEach(_ body: (Self.Element) throws -> Void) rethrows Calls the given closure on each element in the sequence in the same order as a for-in loop.
func lexicographicallyPrecedes<OtherSequence>(_ other: OtherSequence, by areInIncreasingOrder: (Self.Element, Self.Element) throws -> Bool) rethrows -> Bool where OtherSequence : Sequence, Self.Element == OtherSequence.Element Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.
func map<T, E>(_ transform: (Self.Element) throws(E) -> T) throws(E) -> [T] where E : Error Returns an array containing the results of mapping the given closure over the sequence’s elements.
@warn_unqualified_access func max(by areInIncreasingOrder: (Self.Element, Self.Element) throws -> Bool) rethrows -> Self.Element? Returns the maximum element in the sequence, using the given predicate as the comparison between elements.
@warn_unqualified_access func min(by areInIncreasingOrder: (Self.Element, Self.Element) throws -> Bool) rethrows -> Self.Element? Returns the minimum element in the sequence, using the given predicate as the comparison between elements.
func prefix(_ maxLength: Int) -> PrefixSequence<Self> Returns a sequence, up to the specified maximum length, containing the initial elements of the sequence.
func prefix(while predicate: (Self.Element) throws -> Bool) rethrows -> [Self.Element] Returns a sequence containing the initial, consecutive elements that satisfy the given predicate.
func reduce<Result>(_ initialResult: Result, _ nextPartialResult: (Result, Self.Element) throws -> Result) rethrows -> Result Returns the result of combining the elements of the sequence using the given closure.
func reduce<Result>(into initialResult: Result, _ updateAccumulatingResult: (inout Result, Self.Element) throws -> ()) rethrows -> Result Returns the result of combining the elements of the sequence using the given closure.
func reversed() -> [Self.Element] Returns an array containing the elements of this sequence in reverse order.
func shuffled() -> [Self.Element] Returns the elements of the sequence, shuffled.
func shuffled<T>(using generator: inout T) -> [Self.Element] where T : RandomNumberGenerator Returns the elements of the sequence, shuffled using the given generator as a source for randomness.
func sorted(by areInIncreasingOrder: (Self.Element, Self.Element) throws -> Bool) rethrows -> [Self.Element] Returns the elements of the sequence, sorted using the given predicate as the comparison between elements.
func split(maxSplits: Int = Int.max, omittingEmptySubsequences: Bool = true, whereSeparator isSeparator: (Self.Element) throws -> Bool) rethrows -> [ArraySlice<Self.Element>] Returns the longest possible subsequences of the sequence, in order, that don’t contain elements satisfying the given predicate. Elements that are used to split the sequence are not returned as part of any subsequence.
func starts<PossiblePrefix>(with possiblePrefix: PossiblePrefix, by areEquivalent: (Self.Element, PossiblePrefix.Element) throws -> Bool) rethrows -> Bool where PossiblePrefix : Sequence 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(_ maxLength: Int) -> [Self.Element] Returns a subsequence, up to the given maximum length, containing the final elements of the sequence.
func withContiguousStorageIfAvailable<R>(_ body: (UnsafeBufferPointer<Self.Element>) throws -> R) rethrows -> R? func flatMap<ElementOfResult>(_ transform: (Self.Element) throws -> ElementOfResult?) rethrows -> [ElementOfResult]