Range

struct Range<Element : ForwardIndexType>

A collection of consecutive discrete index values.

Element: Is both the element type and the index type of the collection.

Like other collections, a range containing one element has an endIndex that is the successor of its startIndex; and an empty range has startIndex == endIndex.

Axiom: for any Range r, r[i] == i.

Therefore, if Element has a maximal value, it can serve as an endIndex, but can never be contained in a Range<Element>.

It also follows from the axiom above that (-99..<100)[0] == 0. To prevent confusion (because some expect the result to be -99), in a context where Element is known to be an integer type, subscripting with Element is a compile-time error:

// error: could not find an overload for 'subscript'...
print(Range<Int>(start: -99, end: 100)[0])

However, subscripting that range still works in a generic context:

func brackets<Element: ForwardIndexType>(x: Range<Element>, _ i: Element) -> Element {
    return x[i] // Just forward to subscript
}
print(brackets(Range<Int>(start: -99, end: 100), 0))
// Prints "0"
Inheritance CollectionType, CustomDebugStringConvertible, CustomStringConvertible, Equatable, Indexable, SequenceType, _Reflectable View Protocol Hierarchy →
Associated Types
Generator = RangeGenerator<Element>

Type alias inferred.

Element = Element

Type alias inferred.

Index = Element

Type alias inferred.

SubSequence = Slice<Range<Element>>

Type alias inferred.
Import import Swift

Initializers

init(_:)

Construct a copy of x.

Declaration

init(_ x: Range<Element>)
init(start:end:)

Construct a range with startIndex == start and endIndex == end.

Deprecated: it will be removed in Swift 3. Use the '..<' operator..

Declaration

init(start: Element, end: Element)

Instance Variables

var count: Element.Distance

Returns the number of elements.

Complexity: O(1) if Index conforms to RandomAccessIndexType; O(N) otherwise.

Declaration

var count: Element.Distance { get }

Declared In

CollectionType
var debugDescription: String

A textual representation of self, suitable for debugging.

Declaration

var debugDescription: String { get }
var description: String

A textual representation of self.

Declaration

var description: String { get }
var endIndex: Element

The range's upper bound.

endIndex is not a valid argument to subscript, and is always reachable from startIndex by zero or more applications of successor().

Declaration

var endIndex: Element { get set }
var first: Element?

Returns the first element of self, or nil if self is empty.

Complexity: O(1)

Declaration

var first: Element? { get }

Declared In

CollectionType
var indices: Range<Element>

Returns the range of valid index values.

The result's endIndex is the same as that of self. Because Range is half-open, iterating the values of the result produces all valid subscript arguments for self, omitting its endIndex.

Declaration

var indices: Range<Element> { get }

Declared In

CollectionType
var isEmpty: Bool

Returns true iff self is empty.

Complexity: O(1)

Declaration

var isEmpty: Bool { get }

Declared In

CollectionType
var lazy: LazyCollection<Range<Element>>

A collection with contents identical to self, but on which normally-eager operations such as map and filter are implemented lazily.

See Also: LazySequenceType, LazyCollectionType.

Declaration

var lazy: LazyCollection<Range<Element>> { get }

Declared In

CollectionType
var startIndex: Element

The range's lower bound.

Identical to endIndex in an empty range.

Declaration

var startIndex: Element { get set }

Subscripts

subscript(_: Element)

Access the element at position.

Requires: position is a valid position in self and position != endIndex.

Declaration

subscript(position: Element) -> Element { get }
subscript(_: Element._DisabledRangeIndex)

Declaration

subscript(_: Element._DisabledRangeIndex) -> Element { get }
subscript(_: Range<Element>)

Returns a collection representing a contiguous sub-range of self's elements.

Complexity: O(1)

Declaration

subscript(bounds: Range<Element>) -> Slice<Range<Element>> { get }

Declared In

CollectionType

Instance Methods

func contains(_:)

Returns true iff an element in self satisfies predicate.

Declaration

func contains(@noescape predicate: (Element) throws -> Bool) rethrows -> Bool

Declared In

CollectionType, SequenceType
func dropFirst()

Returns a subsequence containing all but the first element.

Complexity: O(1)

Declaration

func dropFirst() -> Slice<Range<Element>>

Declared In

CollectionType, SequenceType
func dropFirst(_:)

Returns a subsequence containing all but the first n elements.

Requires: n >= 0 Complexity: O(n)

Declaration

func dropFirst(n: Int) -> Slice<Range<Element>>

Declared In

CollectionType, SequenceType
func dropLast()

Returns a subsequence containing all but the last element.

Requires: self is a finite sequence. Complexity: O(self.count)

Declaration

func dropLast() -> Slice<Range<Element>>

Declared In

CollectionType, SequenceType
func dropLast(_:)

Returns a subsequence containing all but the last n elements.

Requires: n >= 0 Complexity: O(self.count)

Declaration

func dropLast(n: Int) -> Slice<Range<Element>>

Declared In

CollectionType, SequenceType
func elementsEqual(_:)

Returns true iff self and other contain the same elements in the same order.

Declaration

func elementsEqual<OtherSequence : SequenceType where OtherSequence.Generator.Element == Generator.Element>(other: OtherSequence) -> Bool

Declared In

CollectionType, SequenceType
func elementsEqual(_:isEquivalent:)

Returns true iff self and other contain equivalent elements, using isEquivalent as the equivalence test.

Requires: isEquivalent is an equivalence relation.

Declaration

func elementsEqual<OtherSequence : SequenceType where OtherSequence.Generator.Element == Generator.Element>(other: OtherSequence, @noescape isEquivalent: (Element, Element) throws -> Bool) rethrows -> Bool

Declared In

CollectionType, SequenceType
func enumerate()

Returns a lazy SequenceType containing pairs (n, x), where ns are consecutive Ints starting at zero, and xs are the elements of base:

> for (n, c) in "Swift".characters.enumerate() {
    print("\(n): '\(c)'")
  }
0: 'S'
1: 'w'
2: 'i'
3: 'f'
4: 't'

Declaration

func enumerate() -> EnumerateSequence<Range<Element>>

Declared In

CollectionType, SequenceType
func filter(_:)

Returns an Array containing the elements of self, in order, that satisfy the predicate includeElement.

Declaration

func filter(@noescape includeElement: (Element) throws -> Bool) rethrows -> [Element]

Declared In

CollectionType, SequenceType
func flatMap<T>(_: (Element) throws -> T?)

Returns an Array containing the non-nil results of mapping transform over self.

Complexity: O(M + N), where M is the length of self and N is the length of the result.

Declaration

func flatMap<T>(@noescape transform: (Element) throws -> T?) rethrows -> [T]

Declared In

CollectionType, SequenceType
func flatMap<S : SequenceType>(_: (Element) throws -> S)

Returns an Array containing the concatenated results of mapping transform over self.

s.flatMap(transform)

is equivalent to

Array(s.map(transform).flatten())

Complexity: O(M + N), where M is the length of self and N is the length of the result.

Declaration

func flatMap<S : SequenceType>(transform: (Element) throws -> S) rethrows -> [S.Generator.Element]

Declared In

CollectionType, SequenceType
func forEach(_:)

Call body on each element in self in the same order as a for-in loop.

sequence.forEach {
  // body code
}

is similar to:

for element in sequence {
  // body code
}

Note: You cannot use the break or continue statement to exit the current call of the body closure or skip subsequent calls. Note: Using the return statement in the body closure will only exit from the current call to body, not any outer scope, and won't skip subsequent calls.

Complexity: O(self.count)

Declaration

func forEach(@noescape body: (Element) throws -> Void) rethrows

Declared In

CollectionType, SequenceType
func generate()

Returns a generator over the elements of this sequence.

Complexity: O(1).

Declaration

func generate() -> RangeGenerator<Element>
func indexOf(_:)

Returns the first index where predicate returns true for the corresponding value, or nil if such value is not found.

Complexity: O(self.count).

Declaration

func indexOf(@noescape predicate: (Element) throws -> Bool) rethrows -> Element?

Declared In

CollectionType
func lexicographicalCompare(_:isOrderedBefore:)

Returns true iff self precedes other in a lexicographical ("dictionary") ordering, using isOrderedBefore as the comparison between elements.

Note: This method implements the mathematical notion of lexicographical ordering, which has no connection to Unicode. If you are sorting strings to present to the end-user, you should use String APIs that perform localized comparison.

Requires: isOrderedBefore is a strict weak ordering over the elements of self and other.

Declaration

func lexicographicalCompare<OtherSequence : SequenceType where OtherSequence.Generator.Element == Generator.Element>(other: OtherSequence, @noescape isOrderedBefore: (Element, Element) throws -> Bool) rethrows -> Bool

Declared In

CollectionType, SequenceType
func map(_:)

Returns an Array containing the results of mapping transform over self.

Complexity: O(N).

Declaration

func map<T>(@noescape transform: (Element) throws -> T) rethrows -> [T]

Declared In

CollectionType, SequenceType
func maxElement(_:)

Returns the maximum element in self or nil if the sequence is empty.

Complexity: O(elements.count).

Requires: isOrderedBefore is a strict weak ordering over self.

Declaration

func maxElement(@noescape isOrderedBefore: (Element, Element) throws -> Bool) rethrows -> Element?

Declared In

CollectionType, SequenceType
func minElement(_:)

Returns the minimum element in self or nil if the sequence is empty.

Complexity: O(elements.count).

Requires: isOrderedBefore is a strict weak ordering over self.

Declaration

func minElement(@noescape isOrderedBefore: (Element, Element) throws -> Bool) rethrows -> Element?

Declared In

CollectionType, SequenceType
func prefix(_:)

Returns a subsequence, up to maxLength in length, containing the initial elements.

If maxLength exceeds self.count, the result contains all the elements of self.

Requires: maxLength >= 0 Complexity: O(maxLength)

Declaration

func prefix(maxLength: Int) -> Slice<Range<Element>>

Declared In

CollectionType, SequenceType
func prefixThrough(_:)

Returns prefixUpTo(position.successor())

Complexity: O(1)

Declaration

func prefixThrough(position: Element) -> Slice<Range<Element>>

Declared In

CollectionType
func prefixUpTo(_:)

Returns self[startIndex..<end]

Complexity: O(1)

Declaration

func prefixUpTo(end: Element) -> Slice<Range<Element>>

Declared In

CollectionType
func reduce(_:combine:)

Returns the result of repeatedly calling combine with an accumulated value initialized to initial and each element of self, in turn, i.e. return combine(combine(...combine(combine(initial, self[0]), self[1]),...self[count-2]), self[count-1]).

Declaration

func reduce<T>(initial: T, @noescape combine: (T, Element) throws -> T) rethrows -> T

Declared In

CollectionType, SequenceType
func reverse()

Returns an Array containing the elements of self in reverse order.

Complexity: O(N), where N is the length of self.

Declaration

func reverse() -> [Element]

Declared In

CollectionType, SequenceType
func sort(_:)

Returns an Array containing the sorted elements of source according to isOrderedBefore.

The sorting algorithm is not stable (can change the relative order of elements for which isOrderedBefore does not establish an order).

Requires: isOrderedBefore is a strict weak ordering over the elements in self.

Declaration

func sort(@noescape isOrderedBefore: (Element, Element) -> Bool) -> [Element]

Declared In

CollectionType, SequenceType
func split(_:allowEmptySlices:isSeparator:)

Returns the maximal SubSequences of self, in order, that don't contain elements satisfying the predicate isSeparator.

maxSplit: The maximum number of SubSequences to return, minus 1. If maxSplit + 1 SubSequences are returned, the last one is a suffix of self containing the remaining elements. The default value is Int.max.

allowEmptySubsequences: If true, an empty SubSequence is produced in the result for each pair of consecutive elements satisfying isSeparator. The default value is false.

Requires: maxSplit >= 0

Declaration

func split(maxSplit: Int = default, allowEmptySlices: Bool = default, @noescape isSeparator: (Element) throws -> Bool) rethrows -> [Slice<Range<Element>>]

Declared In

CollectionType, SequenceType
func split(_:maxSplit:allowEmptySlices:)

Returns the maximal SubSequences of self, in order, around a separator element.

maxSplit: The maximum number of SubSequences to return, minus 1. If maxSplit + 1 SubSequences are returned, the last one is a suffix of self containing the remaining elements. The default value is Int.max.

allowEmptySubsequences: If true, an empty SubSequence is produced in the result for each pair of consecutive elements satisfying isSeparator. The default value is false.

Requires: maxSplit >= 0

Declaration

func split(separator: Element, maxSplit: Int = default, allowEmptySlices: Bool = default) -> [Slice<Range<Element>>]

Declared In

CollectionType, SequenceType
func startsWith(_:)

Returns true iff the initial elements of self are equal to prefix. Returns true if other is empty.

Declaration

func startsWith<OtherSequence : SequenceType where OtherSequence.Generator.Element == Generator.Element>(other: OtherSequence) -> Bool

Declared In

CollectionType, SequenceType
func startsWith(_:isEquivalent:)

Returns true iff self begins with elements equivalent to those of other, using isEquivalent as the equivalence test. Returns true if other is empty.

Requires: isEquivalent is an equivalence relation.

Declaration

func startsWith<OtherSequence : SequenceType where OtherSequence.Generator.Element == Generator.Element>(other: OtherSequence, @noescape isEquivalent: (Element, Element) throws -> Bool) rethrows -> Bool

Declared In

CollectionType, SequenceType
func suffix(_:)

Returns a slice, up to maxLength in length, containing the final elements of s.

If maxLength exceeds s.count, the result contains all the elements of s.

Requires: maxLength >= 0 Complexity: O(self.count)

Declaration

func suffix(maxLength: Int) -> Slice<Range<Element>>

Declared In

CollectionType, SequenceType
func suffixFrom(_:)

Returns self[start..<endIndex]

Complexity: O(1)

Declaration

func suffixFrom(start: Element) -> Slice<Range<Element>>

Declared In

CollectionType
func underestimateCount()

Returns a value less than or equal to the number of elements in self, nondestructively.

Complexity: O(N).

Declaration

func underestimateCount() -> Int

Declared In

CollectionType, SequenceType

Conditionally Inherited Items

The initializers, methods, and properties listed below may be available on this type under certain conditions (such as methods that are available on Array when its elements are Equatable) or may not ever be available if that determination is beyond SwiftDoc.org's capabilities. Please open an issue on GitHub if you see something out of place!

Where Generator.Element : CollectionType

func flatten()

A concatenation of the elements of self.

Declaration

func flatten() -> FlattenCollection<Range<Element>>

Declared In

CollectionType

Where Generator.Element : CollectionType, Index : BidirectionalIndexType, Generator.Element.Index : BidirectionalIndexType

func flatten()

A concatenation of the elements of self.

Declaration

func flatten() -> FlattenBidirectionalCollection<Range<Element>>

Declared In

CollectionType

Where Generator.Element : Comparable

func lexicographicalCompare(_:)

Returns true iff self precedes other in a lexicographical ("dictionary") ordering, using "<" as the comparison between elements.

Note: This method implements the mathematical notion of lexicographical ordering, which has no connection to Unicode. If you are sorting strings to present to the end-user, you should use String APIs that perform localized comparison.

Declaration

func lexicographicalCompare<OtherSequence : SequenceType where OtherSequence.Generator.Element == Generator.Element>(other: OtherSequence) -> Bool

Declared In

CollectionType, SequenceType
func maxElement()

Returns the maximum element in self or nil if the sequence is empty.

Complexity: O(elements.count).

Declaration

func maxElement() -> Element?

Declared In

CollectionType, SequenceType
func minElement()

Returns the minimum element in self or nil if the sequence is empty.

Complexity: O(elements.count).

Declaration

func minElement() -> Element?

Declared In

CollectionType, SequenceType
func sort()

Returns an Array containing the sorted elements of source.

The sorting algorithm is not stable (can change the relative order of elements that compare equal).

Requires: The less-than operator (func <) defined in the Comparable conformance is a strict weak ordering over the elements in self.

Declaration

func sort() -> [Element]

Declared In

CollectionType, SequenceType

Where Generator.Element : SequenceType

func flatten()

A concatenation of the elements of self.

Declaration

func flatten() -> FlattenSequence<Range<Element>>

Declared In

CollectionType, SequenceType
func joinWithSeparator(_:)

Returns a view, whose elements are the result of interposing a given separator between the elements of the sequence self.

For example, [[1, 2, 3], [4, 5, 6], [7, 8, 9]].joinWithSeparator([-1, -2]) yields [1, 2, 3, -1, -2, 4, 5, 6, -1, -2, 7, 8, 9].

Declaration

func joinWithSeparator<Separator : SequenceType where Separator.Generator.Element == Generator.Element.Generator.Element>(separator: Separator) -> JoinSequence<Range<Element>>

Declared In

CollectionType, SequenceType

Where Generator.Element == String

func joinWithSeparator(_:)

Interpose the separator between elements of self, then concatenate the result. For example:

["foo", "bar", "baz"].joinWithSeparator("-|-") // "foo-|-bar-|-baz"

Declaration

func joinWithSeparator(separator: String) -> String

Declared In

CollectionType, SequenceType

Where Index : BidirectionalIndexType

var last: Element?

Declaration

var last: Element? { get }

Declared In

CollectionType
func dropLast(_:)

Returns a subsequence containing all but the last n elements.

Requires: n >= 0 Complexity: O(n)

Declaration

func dropLast(n: Int) -> Slice<Range<Element>>

Declared In

CollectionType
func reverse()

Returns the elements of self in reverse order.

Complexity: O(1)

Declaration

func reverse() -> ReverseCollection<Range<Element>>

Declared In

CollectionType
func suffix(_:)

Returns a slice, up to maxLength in length, containing the final elements of s.

If maxLength exceeds s.count, the result contains all the elements of s.

Requires: maxLength >= 0 Complexity: O(maxLength)

Declaration

func suffix(maxLength: Int) -> Slice<Range<Element>>

Declared In

CollectionType

Where Index : RandomAccessIndexType

func reverse()

Returns the elements of self in reverse order.

Complexity: O(1)

Declaration

func reverse() -> ReverseRandomAccessCollection<Range<Element>>

Declared In

CollectionType