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61 lines
2.0 KiB
Swift
61 lines
2.0 KiB
Swift
//===--- Repeated.swift - A Collection that repeats a value N times -------===//
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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 - 2015 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 collection whose elements are all identical `Element`s.
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public struct Repeated<Element> : Collection {
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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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public typealias Index = Int
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/// Construct an instance that contains `length` elements having the
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/// value `repeatedValue`.
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internal init(_repeating repeatedValue: Element, length: Int) {
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self.length = length
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self.repeatedValue = repeatedValue
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}
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/// Always zero, which is the index of the first element in a
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/// non-empty instance.
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public var startIndex: Index {
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return 0
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}
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/// Always equal to `length`, which is one greater than the index of
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/// the last element in a non-empty instance.
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public var endIndex: Index {
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return length
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}
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/// Access the element at `position`.
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///
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/// - Requires: `position` is a valid position in `self` and
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/// `position != endIndex`.
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public subscript(position: Int) -> Element {
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_require(position >= 0 && position < length, "Index out of range")
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return repeatedValue
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}
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/// The number of elements in this collection.
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public let length: Int
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/// The value of every element in this collection.
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public let repeatedValue: Element
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}
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/// Return a collection containing `n` repetitions of `elementInstance`.
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public func repeatElement<T>(element: T, count n: Int) -> Repeated<T> {
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return Repeated(_repeating: element, length: n)
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}
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