| //===----------------------------------------------------------------------===// |
| // |
| // This source file is part of the Swift.org open source project |
| // |
| // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors |
| // Licensed under Apache License v2.0 with Runtime Library Exception |
| // |
| // See https://swift.org/LICENSE.txt for license information |
| // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors |
| // |
| //===----------------------------------------------------------------------===// |
| |
| /// A collection of indices for an arbitrary collection |
| @_fixed_layout |
| public struct DefaultIndices<Elements: Collection> { |
| @_versioned |
| internal var _elements: Elements |
| @_versioned |
| internal var _startIndex: Elements.Index |
| @_versioned |
| internal var _endIndex: Elements.Index |
| |
| @_inlineable |
| @_versioned |
| internal init( |
| _elements: Elements, |
| startIndex: Elements.Index, |
| endIndex: Elements.Index |
| ) { |
| self._elements = _elements |
| self._startIndex = startIndex |
| self._endIndex = endIndex |
| } |
| } |
| |
| extension DefaultIndices: Collection { |
| |
| public typealias Index = Elements.Index |
| public typealias Element = Elements.Index |
| public typealias Indices = DefaultIndices<Elements> |
| public typealias SubSequence = DefaultIndices<Elements> |
| public typealias Iterator = IndexingIterator<DefaultIndices<Elements>> |
| |
| @_inlineable |
| public var startIndex: Index { |
| return _startIndex |
| } |
| |
| @_inlineable |
| public var endIndex: Index { |
| return _endIndex |
| } |
| |
| @_inlineable |
| public subscript(i: Index) -> Elements.Index { |
| // FIXME: swift-3-indexing-model: range check. |
| return i |
| } |
| |
| @_inlineable |
| public subscript(bounds: Range<Index>) -> DefaultIndices<Elements> { |
| // FIXME: swift-3-indexing-model: range check. |
| return DefaultIndices( |
| _elements: _elements, |
| startIndex: bounds.lowerBound, |
| endIndex: bounds.upperBound) |
| } |
| |
| @_inlineable |
| public func index(after i: Index) -> Index { |
| // FIXME: swift-3-indexing-model: range check. |
| return _elements.index(after: i) |
| } |
| |
| @_inlineable |
| public func formIndex(after i: inout Index) { |
| // FIXME: swift-3-indexing-model: range check. |
| _elements.formIndex(after: &i) |
| } |
| |
| @_inlineable |
| public var indices: Indices { |
| return self |
| } |
| } |
| |
| extension DefaultIndices: BidirectionalCollection |
| where Elements: BidirectionalCollection { |
| @_inlineable |
| public func index(before i: Index) -> Index { |
| // FIXME: swift-3-indexing-model: range check. |
| return _elements.index(before: i) |
| } |
| |
| @_inlineable |
| public func formIndex(before i: inout Index) { |
| // FIXME: swift-3-indexing-model: range check. |
| _elements.formIndex(before: &i) |
| } |
| } |
| |
| extension DefaultIndices: RandomAccessCollection |
| where Elements: RandomAccessCollection { } |
| |
| extension Collection where Indices == DefaultIndices<Self> { |
| /// The indices that are valid for subscripting the collection, in ascending |
| /// order. |
| /// |
| /// A collection's `indices` property can hold a strong reference to the |
| /// collection itself, causing the collection to be non-uniquely referenced. |
| /// If you mutate the collection while iterating over its indices, a strong |
| /// reference can cause an unexpected copy of the collection. To avoid the |
| /// unexpected copy, use the `index(after:)` method starting with |
| /// `startIndex` to produce indices instead. |
| /// |
| /// var c = MyFancyCollection([10, 20, 30, 40, 50]) |
| /// var i = c.startIndex |
| /// while i != c.endIndex { |
| /// c[i] /= 5 |
| /// i = c.index(after: i) |
| /// } |
| /// // c == MyFancyCollection([2, 4, 6, 8, 10]) |
| @_inlineable // FIXME(sil-serialize-all) |
| public var indices: DefaultIndices<Self> { |
| return DefaultIndices( |
| _elements: self, |
| startIndex: self.startIndex, |
| endIndex: self.endIndex) |
| } |
| } |
| |
| @available(*, deprecated, renamed: "DefaultIndices") |
| public typealias DefaultBidirectionalIndices<T> = DefaultIndices<T> where T : BidirectionalCollection |
| @available(*, deprecated, renamed: "DefaultIndices") |
| public typealias DefaultRandomAccessIndices<T> = DefaultIndices<T> where T : RandomAccessCollection |