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M-x findr-query-replace \<advance(\([^:]+?\),\([ ]+\)by: *\([^(),]*\|[^(),]+([^()]*)[^(),]*\)\(,\(?:[ ]+\)limit: *\(?:[^()]*\|[^()]+([^()]*)[^()]*\)\)?) index(\3,\2stepsFrom: \1\4)
892 lines
30 KiB
Swift
892 lines
30 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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/// A type that provides subscript access to its elements.
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///
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/// - Important: In most cases, it's best to ignore this protocol and use
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/// `CollectionType` instead, as it has a more complete interface.
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public protocol IndexableBase {
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// FIXME(ABI)(compiler limitation): there is no reason for this protocol
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// to exist apart from missing compiler features that we emulate with it.
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//
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// This protocol is almost an implementation detail of the standard
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// library; it is used to deduce things like the `SubSequence` and
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// `Iterator` type from a minimal collection, but it is also used in
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// exposed places like as a constraint on `IndexingIterator`.
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/// A type that represents a valid position in the collection.
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///
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/// Valid indices consist of the position of every element and a
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/// "past the end" position that's not valid for use as a subscript.
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associatedtype Index : Comparable
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/// The position of the first element in a non-empty collection.
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///
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/// In an empty collection, `startIndex == endIndex`.
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///
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/// - Complexity: O(1)
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var startIndex: Index { get }
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/// The collection's "past the end" position.
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///
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/// `endIndex` is not a valid argument to `subscript`, and is always
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/// reachable from `startIndex` by zero or more applications of
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/// `successor()`.
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///
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/// - Complexity: O(1)
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var endIndex: Index { get }
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// The declaration of _Element and subscript here is a trick used to
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// break a cyclic conformance/deduction that Swift can't handle. We
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// need something other than a Collection.Iterator.Element that can
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// be used as IndexingIterator<T>'s Element. Here we arrange for
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// the Collection itself to have an Element type that's deducible from
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// its subscript. Ideally we'd like to constrain this Element to be the same
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// as Collection.Iterator.Element (see below), but we have no way of
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// expressing it today.
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associatedtype _Element
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/// Returns the element at the given `position`.
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///
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/// - Complexity: O(1)
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subscript(position: Index) -> _Element { get }
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// WORKAROUND: rdar://25214066
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associatedtype SubSequence
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subscript(bounds: Range<Index>) -> SubSequence { get }
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/// Performs a range check in O(1), or a no-op when a range check is not
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/// implementable in O(1).
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///
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/// The range check, if performed, is equivalent to:
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///
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/// precondition(bounds.contains(index))
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///
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/// Use this function to perform a cheap range check for QoI purposes when
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/// memory safety is not a concern. Do not rely on this range check for
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/// memory safety.
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///
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/// The default implementation for forward and bidirectional indices is a
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/// no-op. The default implementation for random access indices performs a
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/// range check.
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///
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/// - Complexity: O(1).
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func _failEarlyRangeCheck(index: Index, bounds: Range<Index>)
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/// Performs a range check in O(1), or a no-op when a range check is not
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/// implementable in O(1).
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///
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/// The range check, if performed, is equivalent to:
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///
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/// precondition(
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/// bounds.contains(range.lowerBound) ||
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/// range.lowerBound == bounds.upperBound)
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/// precondition(
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/// bounds.contains(range.upperBound) ||
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/// range.upperBound == bounds.upperBound)
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///
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/// Use this function to perform a cheap range check for QoI purposes when
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/// memory safety is not a concern. Do not rely on this range check for
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/// memory safety.
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///
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/// The default implementation for forward and bidirectional indices is a
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/// no-op. The default implementation for random access indices performs a
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/// range check.
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///
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/// - Complexity: O(1).
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func _failEarlyRangeCheck(range: Range<Index>, bounds: Range<Index>)
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/// Returns the next consecutive `Index` in a discrete sequence of
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/// `Index` values.
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///
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/// - Precondition: `i` has a well-defined successor.
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@warn_unused_result
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func successor(of i: Index) -> Index
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func formSuccessor(i: inout Index)
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}
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public protocol Indexable : IndexableBase {
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/// A type that can represent the number of steps between pairs of
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/// `Index` values where one value is reachable from the other.
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///
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/// Reachability is defined by the ability to produce one value from
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/// the other via zero or more applications of `successor(of: i)`.
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associatedtype IndexDistance : SignedInteger = Int
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@warn_unused_result
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func advance(i: Index, by n: IndexDistance) -> Index
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@warn_unused_result
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func advance(i: Index, by n: IndexDistance, limit: Index) -> Index
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@warn_unused_result
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func distance(from start: Index, to end: Index) -> IndexDistance
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}
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/// The iterator used for collections that don't specify one.
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public struct IndexingIterator<
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Elements : IndexableBase
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// FIXME(compiler limitation):
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// Elements : Collection
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> : IteratorProtocol, Sequence {
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/// Create an *iterator* over the given collection.
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public /// @testable
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init(_elements: Elements) {
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self._elements = _elements
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self._position = _elements.startIndex
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}
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/// Advance to the next element and return it, or `nil` if no next
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/// element exists.
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///
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/// - Precondition: No preceding call to `self.next()` has returned `nil`.
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public mutating func next() -> Elements._Element? {
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if _position == _elements.endIndex { return nil }
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let element = _elements[_position]
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_elements.formSuccessor(&_position)
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return element
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}
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internal let _elements: Elements
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internal var _position: Elements.Index
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}
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/// A multi-pass sequence with addressable positions.
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///
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/// Positions are represented by an associated `Index` type. Whereas
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/// an arbitrary sequence may be consumed as it is traversed, a
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/// collection is multi-pass: any element may be revisited merely by
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/// saving its index.
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///
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/// The sequence view of the elements is identical to the collection
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/// view. In other words, the following code binds the same series of
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/// values to `x` as does `for x in self {}`:
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///
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/// for i in startIndex..<endIndex {
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/// let x = self[i]
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/// }
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public protocol Collection : Indexable, Sequence {
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/// A type that can represent the number of steps between pairs of
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/// `Index` values where one value is reachable from the other.
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///
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/// Reachability is defined by the ability to produce one value from
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/// the other via zero or more applications of `successor(of: i)`.
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associatedtype IndexDistance : SignedInteger = Int
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/// A type that provides the sequence's iteration interface and
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/// encapsulates its iteration state.
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///
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/// By default, a `Collection` satisfies `Sequence` by
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/// supplying a `IndexingIterator` as its associated `Iterator`
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/// type.
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associatedtype Iterator : IteratorProtocol = IndexingIterator<Self>
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// FIXME: Needed here so that the `Iterator` is properly deduced from
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// a custom `makeIterator()` function. Otherwise we get an
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// `IndexingIterator`. <rdar://problem/21539115>
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func makeIterator() -> Iterator
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/// A `Sequence` that can represent a contiguous subrange of `self`'s
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/// elements.
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///
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/// - Note: This associated type appears as a requirement in
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/// `Sequence`, but is restated here with stricter
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/// constraints: in a `Collection`, the `SubSequence` should
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/// also be a `Collection`.
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associatedtype SubSequence : IndexableBase, Sequence = Slice<Self>
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// FIXME(compiler limitation):
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// associatedtype SubSequence : Collection
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// where
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// Iterator.Element == SubSequence.Iterator.Element,
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// SubSequence.Index == Index,
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// SubSequence.SubSequence == SubSequence
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//
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// (<rdar://problem/20715009> Implement recursive protocol
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// constraints)
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//
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// These constraints allow processing collections in generic code by
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// repeatedly slicing them in a loop.
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/// Returns the element at the given `position`.
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subscript(position: Index) -> Iterator.Element { get }
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/// Returns a collection representing a contiguous sub-range of
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/// `self`'s elements.
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///
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/// - Complexity: O(1)
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subscript(bounds: Range<Index>) -> SubSequence { get }
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/// A type for the collection of indices for this collection.
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///
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/// An instance of `Indices` can hold a strong reference to the collection
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/// itself, causing the collection to be non-uniquely referenced. If you
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/// need to mutate the collection while iterating over its indices, use the
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/// `next()` method to produce indices instead.
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associatedtype Indices : IndexableBase, Sequence = DefaultIndices<Self>
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// FIXME(compiler limitation):
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// associatedtype Indices : Collection
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// where
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// Indices.Iterator.Element == Index,
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// Indices.Index == Index,
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// Indices.SubSequence == Indices
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// = DefaultIndices<Self>
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/// The collection of indices of this collection that can be used for
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/// subscripting.
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var indices: Indices { get }
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/// Returns `self[startIndex..<end]`
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///
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/// - Complexity: O(1)
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@warn_unused_result
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func prefix(upTo end: Index) -> SubSequence
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/// Returns `self[start..<endIndex]`
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///
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/// - Complexity: O(1)
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@warn_unused_result
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func suffix(from start: Index) -> SubSequence
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/// Returns `prefix(upTo: position.successor())`
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///
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/// - Complexity: O(1)
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@warn_unused_result
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func prefix(through position: Index) -> SubSequence
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/// Returns `true` iff `self` is empty.
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var isEmpty: Bool { get }
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/// Returns the number of elements.
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///
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/// - Complexity: O(1) if `Index` conforms to `RandomAccessIndex`;
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/// O(N) otherwise.
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var count: IndexDistance { get }
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// The following requirement enables dispatching for indexOf when
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// the element type is Equatable.
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/// Returns `Optional(Optional(index))` if an element was found;
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/// `nil` otherwise.
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///
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/// - Complexity: O(N).
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@warn_unused_result
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func _customIndexOfEquatableElement(element: Iterator.Element) -> Index??
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/// Returns the first element of `self`, or `nil` if `self` is empty.
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var first: Iterator.Element? { get }
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/// Returns the result of advancing `i` by `n` positions.
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///
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/// - Returns:
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/// - If `n > 0`, returns a new index applying `next` on `i` `n`
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/// times.
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/// - If `n < 0`, returns a new index by applying `previous` on `i`
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/// `-n` times.
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/// - Otherwise, `i` unmodified.
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///
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/// - Precondition: `n >= 0` if only conforming to `Collection`
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///
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/// - Complexity:
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/// - O(1) if conforming to `RandomAccessCollection`
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/// - O(`abs(n)`) otherwise
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@warn_unused_result
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func advance(i: Index, by n: IndexDistance) -> Index
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/// Returns the result of advancing `self` by `n` positions, or until it
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/// equals `limit`.
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///
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/// - Returns:
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/// - If `n > 0`, returns `i` modified by applying `next` on `i` `n`
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/// times but not past `limit`.
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/// - If `n < 0`, returns `i` modified by applying `previous` on `i`
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/// `-n` times but not past `limit`.
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/// - Otherwise, return `i` unmodified.
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///
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/// - Precondition: `n >= 0` if only conforming to `Collection`.
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///
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/// - Complexity:
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/// - O(1) if conforming to `RandomAccessCollection`
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/// - O(`abs(n)`) otherwise
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@warn_unused_result
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func advance(i: Index, by n: IndexDistance, limit: Index) -> Index
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/// Measure the distance between `start` and `end` indexes.
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///
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/// - Precondition:
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/// - `start` and `end` are part of the same sequence when conforming to
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/// `RandomAccessSequenceType`.
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/// - `end` is reachable from `start` by incrementation otherwise.
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///
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/// - Complexity:
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/// - O(1) if conforming to `RandomAccessIndex`
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/// - O(`n`) otherwise, where `n` is the function's result.
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@warn_unused_result
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func distance(from start: Index, to end: Index) -> IndexDistance
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}
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/// Default implementation for forward collections.
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extension Indexable {
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@inline(__always)
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public func formSuccessor(i: inout Index) {
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// FIXME: swift-3-indexing-model: tests.
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i = successor(of: i)
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}
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public func _failEarlyRangeCheck(index: Index, bounds: Range<Index>) {
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// FIXME: swift-3-indexing-model: tests.
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_precondition(
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bounds.lowerBound <= index,
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"index is out of bounds: index designates a position before bounds.lowerBound")
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_precondition(
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index < bounds.upperBound,
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"index is out of bounds: index designates the bounds.upperBound position or a position after it")
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}
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public func _failEarlyRangeCheck(range: Range<Index>, bounds: Range<Index>) {
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// FIXME: swift-3-indexing-model: tests.
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_precondition(
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bounds.lowerBound <= range.lowerBound,
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"range.lowerBound is out of bounds: index designates a position before bounds.lowerBound")
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_precondition(
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bounds.lowerBound <= range.upperBound,
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"range.upperBound is out of bounds: index designates a position before bounds.lowerBound")
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_precondition(
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range.lowerBound <= bounds.upperBound,
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"range.lowerBound is out of bounds: index designates a position after bounds.upperBound")
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_precondition(
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range.upperBound <= bounds.upperBound,
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"range.lowerBound is out of bounds: index designates a position after bounds.upperBound")
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}
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@warn_unused_result
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public func advance(i: Index, by n: IndexDistance) -> Index {
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// FIXME: swift-3-indexing-model: tests.
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return self._advanceForward(i, by: n)
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}
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@warn_unused_result
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public func advance(i: Index, by n: IndexDistance, limit: Index) -> Index {
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// FIXME: swift-3-indexing-model: tests.
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return self._advanceForward(i, by: n, limit: limit)
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}
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@warn_unused_result
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public func distance(from start: Index, to end: Index) -> IndexDistance {
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// FIXME: swift-3-indexing-model: tests.
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_precondition(start <= end,
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"Only BidirectionalCollections can have end come before start")
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var start = start
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var count: IndexDistance = 0
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while start != end {
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count = count + 1
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formSuccessor(&start)
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}
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return count
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}
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/// Do not use this method directly; call advanced(by: n) instead.
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@inline(__always)
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@warn_unused_result
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internal func _advanceForward(i: Index, by n: IndexDistance) -> Index {
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_precondition(n >= 0,
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"Only BidirectionalCollections can be advanced by a negative amount")
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var i = i
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for _ in 0..<n {
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formSuccessor(&i)
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}
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return i
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}
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/// Do not use this method directly; call advanced(by: n, limit) instead.
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@inline(__always)
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@warn_unused_result
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internal
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func _advanceForward(i: Index, by n: IndexDistance, limit: Index) -> Index {
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_precondition(n >= 0,
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"Only BidirectionalCollections can be advanced by a negative amount")
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var i = i
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for _ in 0..<n {
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if (limit == i) {
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break;
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}
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formSuccessor(&i)
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}
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return i
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}
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}
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/// Supply optimized defaults for `Collection` models that use some model
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/// of `Strideable` as their `Index`.
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extension Indexable where Index : Strideable {
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@warn_unused_result
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public func successor(of i: Index) -> Index {
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// FIXME: swift-3-indexing-model: tests.
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_failEarlyRangeCheck(i, bounds: startIndex..<endIndex)
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return i.advanced(by: 1)
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}
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/*
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@warn_unused_result
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public func advance(i: Index, by n: IndexDistance) -> Index {
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_precondition(n >= 0,
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"Only BidirectionalCollections can be advanced by a negative amount")
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// FIXME: swift-3-indexing-model: range check i
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// FIXME: swift-3-indexing-model - error: cannot invoke 'advanced' with an argument list of type '(by: Self.IndexDistance)'
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return i.advanced(by: n)
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}
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@warn_unused_result
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public func advance(i: Index, by n: IndexDistance, limit: Index) -> Index {
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_precondition(n >= 0,
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"Only BidirectionalCollections can be advanced by a negative amount")
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// FIXME: swift-3-indexing-model: range check i
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// FIXME: swift-3-indexing-model - error: cannot invoke 'advanced' with an argument list of type '(by: Self.IndexDistance)'
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let i = i.advanced(by: n)
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if (i >= limit) {
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return limit
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}
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return i
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}
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@warn_unused_result
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public func distance(from start: Index, to end: Index) -> IndexDistance {
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_precondition(start <= end,
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"Only BidirectionalCollections can have end come before start")
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// FIXME: swift-3-indexing-model: range check supplied start and end?
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// FIXME: swift-3-indexing-model - error: cannot invoke 'distance' with an argument list of type '(to: Self.Index)'
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return start.distance(to: end)
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}
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*/
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}
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/// Supply the default `makeIterator()` method for `Collection` models
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/// that accept the default associated `Iterator`,
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/// `IndexingIterator<Self>`.
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extension Collection where Iterator == IndexingIterator<Self> {
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public func makeIterator() -> IndexingIterator<Self> {
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return IndexingIterator(_elements: self)
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}
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}
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/// Supply the default "slicing" `subscript` for `Collection` models
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/// that accept the default associated `SubSequence`, `Slice<Self>`.
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extension Collection where SubSequence == Slice<Self> {
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public subscript(bounds: Range<Index>) -> Slice<Self> {
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_failEarlyRangeCheck(bounds, bounds: startIndex..<endIndex)
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return Slice(base: self, bounds: bounds)
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}
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}
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// TODO: swift-3-indexing-model - review the following
|
|
extension Collection where SubSequence == Self {
|
|
/// If `!self.isEmpty`, remove the first element and return it, otherwise
|
|
/// return `nil`.
|
|
///
|
|
/// - Complexity: O(1)
|
|
@warn_unused_result
|
|
public mutating func popFirst() -> Iterator.Element? {
|
|
guard !isEmpty else { return nil }
|
|
let element = first!
|
|
self = self[successor(of: startIndex)..<endIndex]
|
|
return element
|
|
}
|
|
}
|
|
|
|
/// Default implementations of core requirements
|
|
extension Collection {
|
|
/// Returns `true` iff `self` is empty.
|
|
///
|
|
/// - Complexity: O(1)
|
|
public var isEmpty: Bool {
|
|
return startIndex == endIndex
|
|
}
|
|
|
|
/// Returns the first element of `self`, or `nil` if `self` is empty.
|
|
///
|
|
/// - Complexity: O(1)
|
|
public var first: Iterator.Element? {
|
|
// NB: Accessing `startIndex` may not be O(1) for some lazy collections,
|
|
// so instead of testing `isEmpty` and then returning the first element,
|
|
// we'll just rely on the fact that the iterator always yields the
|
|
// first element first.
|
|
var i = makeIterator()
|
|
return i.next()
|
|
}
|
|
// TODO: swift-3-indexing-model - uncomment and replace above ready (or should we still use the iterator one?)
|
|
/// Returns the first element of `self`, or `nil` if `self` is empty.
|
|
///
|
|
/// - Complexity: O(1)
|
|
// public var first: Iterator.Element? {
|
|
// return isEmpty ? nil : self[startIndex]
|
|
// }
|
|
|
|
// TODO: swift-3-indexing-model - review the following
|
|
/// Returns a value less than or equal to the number of elements in
|
|
/// `self`, *nondestructively*.
|
|
///
|
|
/// - Complexity: O(`count`).
|
|
public var underestimatedCount: Int {
|
|
return numericCast(count)
|
|
}
|
|
|
|
/// Returns the number of elements.
|
|
///
|
|
/// - Complexity: O(1) if `Index` conforms to `RandomAccessIndex`;
|
|
/// O(N) otherwise.
|
|
public var count: IndexDistance {
|
|
return distance(from: startIndex, to: endIndex)
|
|
}
|
|
|
|
// TODO: swift-3-indexing-model - rename the following to _customIndexOfEquatable(element)?
|
|
/// Customization point for `Sequence.index(of:)`.
|
|
///
|
|
/// Define this method if the collection can find an element in less than
|
|
/// O(N) by exploiting collection-specific knowledge.
|
|
///
|
|
/// - Returns: `nil` if a linear search should be attempted instead,
|
|
/// `Optional(nil)` if the element was not found, or
|
|
/// `Optional(Optional(index))` if an element was found.
|
|
///
|
|
/// - Complexity: O(`count`).
|
|
@warn_unused_result
|
|
public // dispatching
|
|
func _customIndexOfEquatableElement(_: Iterator.Element) -> Index?? {
|
|
return nil
|
|
}
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Default implementations for Collection
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
extension Collection {
|
|
// TODO: swift-3-indexing-model - review the following
|
|
/// Returns an `Array` containing the results of mapping `transform`
|
|
/// over `self`.
|
|
///
|
|
/// - Complexity: O(N).
|
|
@warn_unused_result
|
|
public func map<T>(
|
|
@noescape transform: (Iterator.Element) throws -> T
|
|
) rethrows -> [T] {
|
|
let count: Int = numericCast(self.count)
|
|
if count == 0 {
|
|
return []
|
|
}
|
|
|
|
var result = ContiguousArray<T>()
|
|
result.reserveCapacity(count)
|
|
|
|
var i = self.startIndex
|
|
|
|
for _ in 0..<count {
|
|
result.append(try transform(self[i]))
|
|
formSuccessor(&i)
|
|
}
|
|
|
|
_expectEnd(i, self)
|
|
return Array(result)
|
|
}
|
|
|
|
/// Returns a subsequence containing all but the first `n` elements.
|
|
///
|
|
/// - Precondition: `n >= 0`
|
|
/// - Complexity: O(`n`)
|
|
@warn_unused_result
|
|
public func dropFirst(n: Int) -> SubSequence {
|
|
_precondition(n >= 0, "Can't drop a negative number of elements from a collection")
|
|
let start = index(numericCast(n), stepsFrom: startIndex, limit: endIndex)
|
|
return self[start..<endIndex]
|
|
}
|
|
|
|
/// Returns a subsequence containing all but the last `n` elements.
|
|
///
|
|
/// - Precondition: `n >= 0`
|
|
/// - Complexity: O(`self.count`)
|
|
@warn_unused_result
|
|
public func dropLast(n: Int) -> SubSequence {
|
|
_precondition(
|
|
n >= 0, "Can't drop a negative number of elements from a collection")
|
|
let amount = Swift.max(0, numericCast(count) - n)
|
|
let end = index(numericCast(amount), stepsFrom: startIndex, limit: endIndex)
|
|
return self[startIndex..<end]
|
|
}
|
|
|
|
/// 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`.
|
|
///
|
|
/// - Precondition: `maxLength >= 0`
|
|
/// - Complexity: O(`maxLength`)
|
|
@warn_unused_result
|
|
public func prefix(maxLength: Int) -> SubSequence {
|
|
_precondition(
|
|
maxLength >= 0,
|
|
"Can't take a prefix of negative length from a collection")
|
|
let end = index(numericCast(maxLength), stepsFrom: startIndex, limit: endIndex)
|
|
return self[startIndex..<end]
|
|
}
|
|
|
|
/// Returns a slice, up to `maxLength` in length, containing the
|
|
/// final elements of `self`.
|
|
///
|
|
/// If `maxLength` exceeds `s.count`, the result contains all
|
|
/// the elements of `self`.
|
|
///
|
|
/// - Precondition: `maxLength >= 0`
|
|
/// - Complexity: O(`self.count`)
|
|
@warn_unused_result
|
|
public func suffix(maxLength: Int) -> SubSequence {
|
|
_precondition(
|
|
maxLength >= 0,
|
|
"Can't take a suffix of negative length from a collection")
|
|
let amount = Swift.max(0, numericCast(count) - maxLength)
|
|
let start = index(numericCast(amount), stepsFrom: startIndex, limit: endIndex)
|
|
return self[start..<endIndex]
|
|
}
|
|
|
|
/// Returns `self[startIndex..<end]`
|
|
///
|
|
/// - Complexity: O(1)
|
|
@warn_unused_result
|
|
public func prefix(upTo end: Index) -> SubSequence {
|
|
return self[startIndex..<end]
|
|
}
|
|
|
|
/// Returns `self[start..<endIndex]`
|
|
///
|
|
/// - Complexity: O(1)
|
|
@warn_unused_result
|
|
public func suffix(from start: Index) -> SubSequence {
|
|
return self[start..<endIndex]
|
|
}
|
|
|
|
/// Returns `prefix(upTo: position.successor())`
|
|
///
|
|
/// - Complexity: O(1)
|
|
@warn_unused_result
|
|
public func prefix(through position: Index) -> SubSequence {
|
|
return prefix(upTo: successor(of: position))
|
|
}
|
|
|
|
// TODO: swift-3-indexing-model - review the following
|
|
/// Returns the maximal `SubSequence`s of `self`, in order, that
|
|
/// don't contain elements satisfying the predicate `isSeparator`.
|
|
///
|
|
/// - Parameter maxSplits: The maximum number of `SubSequence`s to
|
|
/// return, minus 1.
|
|
/// If `maxSplits + 1` `SubSequence`s are returned, the last one is
|
|
/// a suffix of `self` containing *all* the elements of `self` following the
|
|
/// last split point.
|
|
/// The default value is `Int.max`.
|
|
///
|
|
/// - Parameter omittingEmptySubsequences: If `false`, an empty `SubSequence`
|
|
/// is produced in the result for each pair of consecutive elements
|
|
/// satisfying `isSeparator`.
|
|
/// The default value is `true`.
|
|
///
|
|
/// - Precondition: `maxSplits >= 0`
|
|
@warn_unused_result
|
|
public func split(
|
|
maxSplits maxSplits: Int = Int.max,
|
|
omittingEmptySubsequences: Bool = true,
|
|
@noescape isSeparator: (Iterator.Element) throws -> Bool
|
|
) rethrows -> [SubSequence] {
|
|
_precondition(maxSplits >= 0, "Must take zero or more splits")
|
|
|
|
var result: [SubSequence] = []
|
|
var subSequenceStart: Index = startIndex
|
|
|
|
func appendSubsequence(end end: Index) -> Bool {
|
|
if subSequenceStart == end && omittingEmptySubsequences {
|
|
return false
|
|
}
|
|
result.append(self[subSequenceStart..<end])
|
|
return true
|
|
}
|
|
|
|
if maxSplits == 0 || isEmpty {
|
|
appendSubsequence(end: endIndex)
|
|
return result
|
|
}
|
|
|
|
var subSequenceEnd = subSequenceStart
|
|
let cachedEndIndex = endIndex
|
|
while subSequenceEnd != cachedEndIndex {
|
|
if try isSeparator(self[subSequenceEnd]) {
|
|
let didAppend = appendSubsequence(end: subSequenceEnd)
|
|
formSuccessor(&subSequenceEnd)
|
|
subSequenceStart = subSequenceEnd
|
|
if didAppend && result.count == maxSplits {
|
|
break
|
|
}
|
|
continue
|
|
}
|
|
formSuccessor(&subSequenceEnd)
|
|
}
|
|
|
|
if subSequenceStart != cachedEndIndex || !omittingEmptySubsequences {
|
|
result.append(self[subSequenceStart..<cachedEndIndex])
|
|
}
|
|
|
|
return result
|
|
}
|
|
}
|
|
|
|
// TODO: swift-3-indexing-model - review the following
|
|
extension Collection where Iterator.Element : Equatable {
|
|
/// Returns the maximal `SubSequence`s of `self`, in order, around a
|
|
/// `separator` element.
|
|
///
|
|
/// - Parameter maxSplits: The maximum number of `SubSequence`s to
|
|
/// return, minus 1.
|
|
/// If `maxSplits + 1` `SubSequence`s are returned, the last one is
|
|
/// a suffix of `self` containing *all* the elements of `self` following the
|
|
/// last split point.
|
|
/// The default value is `Int.max`.
|
|
///
|
|
/// - Parameter omittingEmptySubsequences: If `false`, an empty `SubSequence`
|
|
/// is produced in the result for each pair of consecutive elements
|
|
/// equal to `separator`.
|
|
/// The default value is `true`.
|
|
///
|
|
/// - Precondition: `maxSplits >= 0`
|
|
@warn_unused_result
|
|
public func split(
|
|
separator separator: Iterator.Element,
|
|
maxSplits: Int = Int.max,
|
|
omittingEmptySubsequences: Bool = true
|
|
) -> [SubSequence] {
|
|
return split(
|
|
maxSplits: maxSplits,
|
|
omittingEmptySubsequences: omittingEmptySubsequences,
|
|
isSeparator: { $0 == separator })
|
|
}
|
|
}
|
|
|
|
// TODO: swift-3-indexing-model - review the following
|
|
extension Collection where SubSequence == Self {
|
|
/// Remove the element at `startIndex` and return it.
|
|
///
|
|
/// - Complexity: O(1)
|
|
/// - Precondition: `!self.isEmpty`.
|
|
public mutating func removeFirst() -> Iterator.Element {
|
|
_precondition(!isEmpty, "can't remove items from an empty collection")
|
|
let element = first!
|
|
self = self[successor(of: startIndex)..<endIndex]
|
|
return element
|
|
}
|
|
|
|
/// Remove the first `n` elements.
|
|
///
|
|
/// - Complexity:
|
|
/// - O(1) if `Index` conforms to `RandomAccessIndex`
|
|
/// - O(n) otherwise
|
|
/// - Precondition: `n >= 0 && self.count >= n`.
|
|
public mutating func removeFirst(n: Int) {
|
|
if n == 0 { return }
|
|
_precondition(n >= 0, "number of elements to remove should be non-negative")
|
|
_precondition(count >= numericCast(n),
|
|
"can't remove more items from a collection than it contains")
|
|
self = self[index(numericCast(n), stepsFrom: startIndex)..<endIndex]
|
|
}
|
|
}
|
|
|
|
// TODO: swift-3-indexing-model - review the following
|
|
extension Sequence
|
|
where Self : _ArrayProtocol, Self.Element == Self.Iterator.Element {
|
|
// A fast implementation for when you are backed by a contiguous array.
|
|
public func _copyContents(
|
|
initializing ptr: UnsafeMutablePointer<Iterator.Element>
|
|
) -> UnsafeMutablePointer<Iterator.Element> {
|
|
let s = self._baseAddressIfContiguous
|
|
if s != nil {
|
|
let count = self.count
|
|
ptr.initializeFrom(s, count: count)
|
|
_fixLifetime(self._owner)
|
|
return ptr + count
|
|
} else {
|
|
var p = ptr
|
|
for x in self {
|
|
p.initialize(with: x)
|
|
p += 1
|
|
}
|
|
return p
|
|
}
|
|
}
|
|
}
|
|
|
|
// TODO: swift-3-indexing-model - review the following
|
|
extension Collection {
|
|
public func _preprocessingPass<R>(@noescape preprocess: () -> R) -> R? {
|
|
return preprocess()
|
|
}
|
|
}
|
|
|
|
@available(*, unavailable, message: "Bit enum has been deprecated. Please use Int instead.")
|
|
public enum Bit {}
|
|
|
|
@available(*, unavailable, renamed: "IndexingIterator")
|
|
public struct IndexingGenerator<Elements : IndexableBase> {}
|
|
|
|
@available(*, unavailable, renamed: "Collection")
|
|
public typealias CollectionType = Collection
|
|
|
|
extension Collection {
|
|
@available(*, unavailable, renamed: "Iterator")
|
|
public typealias Generator = Iterator
|
|
|
|
@available(*, unavailable, renamed: "iterator")
|
|
public func generate() -> Iterator {
|
|
fatalError("unavailable function can't be called")
|
|
}
|
|
|
|
@available(*, unavailable, message: "Removed in Swift 3. Please use underestimatedCount property.")
|
|
public func underestimateCount() -> Int {
|
|
fatalError("unavailable function can't be called")
|
|
}
|
|
|
|
@available(*, unavailable, message: "Please use split(_:omittingEmptySubsequences:isSeparator:) instead")
|
|
public func split(
|
|
maxSplit: Int = Int.max,
|
|
allowEmptySlices: Bool = false,
|
|
@noescape isSeparator: (Iterator.Element) throws -> Bool
|
|
) rethrows -> [SubSequence] {
|
|
fatalError("unavailable function can't be called")
|
|
}
|
|
}
|
|
|
|
extension Collection where Iterator.Element : Equatable {
|
|
@available(*, unavailable, message: "Please use split(separator:maxSplits:omittingEmptySubsequences:) instead")
|
|
public func split(
|
|
separator: Iterator.Element,
|
|
maxSplit: Int = Int.max,
|
|
allowEmptySlices: Bool = false
|
|
) -> [SubSequence] {
|
|
fatalError("unavailable function can't be called")
|
|
}
|
|
}
|
|
|
|
@available(*, unavailable, message: "PermutationGenerator has been removed in Swift 3")
|
|
public struct PermutationGenerator<C : Collection, Indices : Sequence> {}
|