Instance Method

formIndex(_:offsetBy:limitedBy:)

Offsets the given index by the specified distance, or so that it equals the given limiting index.

Declaration

func formIndex(_ i: inout Bound, offsetBy distance: Int, limitedBy limit: Bound) -> Bool

Parameters

i

A valid index of the collection.

distance

The distance to offset i. distance must not be negative unless the collection conforms to the BidirectionalCollection protocol.

limit

A valid index of the collection to use as a limit. If distance > 0, a limit that is less than i has no effect. Likewise, if distance < 0, a limit that is greater than i has no effect.

Return Value

true if i has been offset by exactly distance steps without going beyond limit; otherwise, false. When the return value is false, the value of i is equal to limit.

Discussion

The value passed as distance must not offset i beyond the bounds of the collection, unless the index passed as limit prevents offsetting beyond those bounds.

Complexity: O(1) if the collection conforms to RandomAccessCollection; otherwise, O(k), where k is the absolute value of distance.

See Also

Manipulating Indices

var startIndex: Bound

The position of the first element in a nonempty collection.

var endIndex: Bound

The collection’s “past the end” position—that is, the position one greater than the last valid subscript argument.

var indices: Range<Bound>

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

var indices: Range<Bound>

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

func index(after: Range<Bound>.Index) -> Range<Bound>.Index

Returns the position immediately after the given index.

func formIndex(after: inout Bound)

Replaces the given index with its successor.

func index(before: Range<Bound>.Index) -> Range<Bound>.Index

Returns the position immediately before the given index.

func formIndex(before: inout Bound)

Replaces the given index with its predecessor.

func index(Bound, offsetBy: Int, limitedBy: Bound) -> Bound?

Returns an index that is the specified distance from the given index, unless that distance is beyond a given limiting index.

func formIndex(inout Bound, offsetBy: Int)

Offsets the given index by the specified distance.

func index(Range<Bound>.Index, offsetBy: Int) -> Range<Bound>.Index

Returns an index that is the specified distance from the given index.

func distance(from: Range<Bound>.Index, to: Range<Bound>.Index) -> Int

Returns the distance between two indices.

func hash(into: inout Hasher)

Hashes the essential components of this value by feeding them into the given hasher.