Cursor

Overview

To iterate over the elements of a cursor, use a while loop:

while let element = try cursor.next() {
    print(element)
}

Relationship with standard Sequence and IteratorProtocol

Cursors share traits with lazy sequences and iterators from the Swift standard library. Differences are:

• Cursor types are classes, and have a lifetime.

• Cursor iteration may throw errors.

• A cursor can not be repeated.

The protocol comes with default implementations for many operations similar to those defined by Swift’s Sequence protocol: contains, dropFirst, dropLast, drop(while:), enumerated, filter, first, flatMap, forEach, joined, joined(separator:), max, max(by:), min, min(by:), map, prefix, prefix(while:), reduce, reduce(into:), suffix.

Supporting Types

• class AnyCursor<Element>

  A type-erased cursor.

• class DropFirstCursor<Base>

  A Cursor that consumes and drops n elements from an underlying Base cursor before possibly returning the first available element.

• class DropWhileCursor<Base>

  A Cursor whose elements consist of the elements that follow the initial consecutive elements of some Base cursor that satisfy a given predicate.

• class EnumeratedCursor<Base>

  An enumeration of the elements of a cursor.

• class FilterCursor<Base>

  A Cursor whose elements consist of the elements of some Base cursor that also satisfy a given predicate.

• class FlattenCursor<Base>

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

• class MapCursor<Base, Element>

  A Cursor whose elements consist of those in a Base cursor passed through a transform function returning Element.

• class PrefixCursor<Base>

  A Cursor that only consumes up to n elements from an underlying Base cursor.

• class PrefixWhileCursor<Base>

  A Cursor whose elements consist of the initial consecutive elements of some Base cursor that satisfy a given predicate.