File: ClosedRange.swift

package info (click to toggle)
swiftlang 6.0.3-2
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid, trixie
  • size: 2,519,992 kB
  • sloc: cpp: 9,107,863; ansic: 2,040,022; asm: 1,135,751; python: 296,500; objc: 82,456; f90: 60,502; lisp: 34,951; pascal: 19,946; sh: 18,133; perl: 7,482; ml: 4,937; javascript: 4,117; makefile: 3,840; awk: 3,535; xml: 914; fortran: 619; cs: 573; ruby: 573
file content (508 lines) | stat: -rw-r--r-- 16,655 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
//===--- ClosedRange.swift ------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// FIXME: swift-3-indexing-model: Generalize all tests to check both
// [Closed]Range.

/// An interval from a lower bound up to, and including, an upper bound.
///
/// You create a `ClosedRange` instance by using the closed range
/// operator (`...`).
///
///     let throughFive = 0...5
///
/// A `ClosedRange` instance contains both its lower bound and its
/// upper bound.
///
///     throughFive.contains(3)
///     // true
///     throughFive.contains(10)
///     // false
///     throughFive.contains(5)
///     // true
///
/// Because a closed range includes its upper bound, a closed range whose lower
/// bound is equal to the upper bound contains that value. Therefore, a
/// `ClosedRange` instance cannot represent an empty range.
///
///     let zeroInclusive = 0...0
///     zeroInclusive.contains(0)
///     // true
///     zeroInclusive.isEmpty
///     // false
///
/// Using a Closed Range as a Collection of Consecutive Values
/// ----------------------------------------------------------
///
/// When a closed range uses integers as its lower and upper bounds, or any
/// other type that conforms to the `Strideable` protocol with an integer
/// stride, you can use that range in a `for`-`in` loop or with any sequence or
/// collection method. The elements of the range are the consecutive values
/// from its lower bound up to, and including, its upper bound.
///
///     for n in 3...5 {
///         print(n)
///     }
///     // Prints "3"
///     // Prints "4"
///     // Prints "5"
///
/// Because floating-point types such as `Float` and `Double` are their own
/// `Stride` types, they cannot be used as the bounds of a countable range. If
/// you need to iterate over consecutive floating-point values, see the
/// `stride(from:through:by:)` function.
@frozen
public struct ClosedRange<Bound: Comparable> {
  /// The range's lower bound.
  public let lowerBound: Bound

  /// The range's upper bound.
  public let upperBound: Bound

  // This works around _debugPrecondition() impacting the performance of
  // optimized code. (rdar://72246338)
  @_alwaysEmitIntoClient @inline(__always)
  internal init(_uncheckedBounds bounds: (lower: Bound, upper: Bound)) {
    self.lowerBound = bounds.lower
    self.upperBound = bounds.upper
  }

  /// Creates an instance with the given bounds.
  ///
  /// Because this initializer does not perform any checks, it should be used
  /// as an optimization only when you are absolutely certain that `lower` is
  /// less than or equal to `upper`. Using the closed range operator (`...`)
  /// to form `ClosedRange` instances is preferred.
  ///
  /// - Parameter bounds: A tuple of the lower and upper bounds of the range.
  @inlinable
  public init(uncheckedBounds bounds: (lower: Bound, upper: Bound)) {
    _debugPrecondition(bounds.lower <= bounds.upper,
      "ClosedRange requires lowerBound <= upperBound")
    self.init(_uncheckedBounds: (lower: bounds.lower, upper: bounds.upper))
  }
}

// define isEmpty, which is available even on an uncountable ClosedRange
extension ClosedRange {
  /// A Boolean value indicating whether the range contains no elements.
  ///
  /// Because a closed range cannot represent an empty range, this property is
  /// always `false`.
  @inlinable
  public var isEmpty: Bool {
    return false
  }
}

extension ClosedRange: RangeExpression {
  @inlinable // trivial-implementation
  public func relative<C: Collection>(to collection: C) -> Range<Bound>
  where C.Index == Bound {
    return Range(
      _uncheckedBounds: (
        lower: lowerBound,
        upper: collection.index(after: self.upperBound)))
  }

  /// Returns a Boolean value indicating whether the given element is contained
  /// within the range.
  ///
  /// A `ClosedRange` instance contains both its lower and upper bound.
  /// `element` is contained in the range if it is between the two bounds or
  /// equal to either bound.
  ///
  /// - Parameter element: The element to check for containment.
  /// - Returns: `true` if `element` is contained in the range; otherwise,
  ///   `false`.
  @inlinable
  public func contains(_ element: Bound) -> Bool {
    return element >= self.lowerBound && element <= self.upperBound
  }
}

extension ClosedRange: Sequence
where Bound: Strideable, Bound.Stride: SignedInteger {
  public typealias Element = Bound
  public typealias Iterator = IndexingIterator<ClosedRange<Bound>>
}

extension ClosedRange where Bound: Strideable, Bound.Stride: SignedInteger {
  @frozen // FIXME(resilience)
  public enum Index {
    case pastEnd
    case inRange(Bound)
  }
}

extension ClosedRange.Index: Comparable {
  @inlinable
  public static func == (
    lhs: ClosedRange<Bound>.Index,
    rhs: ClosedRange<Bound>.Index
  ) -> Bool {
    switch (lhs, rhs) {
    case (.inRange(let l), .inRange(let r)):
      return l == r
    case (.pastEnd, .pastEnd):
      return true
    default:
      return false
    }
  }

  @inlinable
  public static func < (
    lhs: ClosedRange<Bound>.Index,
    rhs: ClosedRange<Bound>.Index
  ) -> Bool {
    switch (lhs, rhs) {
    case (.inRange(let l), .inRange(let r)):
      return l < r
    case (.inRange, .pastEnd):
      return true
    default:
      return false
    }
  }
}

extension ClosedRange.Index: Hashable
where Bound: Strideable, Bound.Stride: SignedInteger, Bound: Hashable {
  /// Hashes the essential components of this value by feeding them into the
  /// given hasher.
  ///
  /// - Parameter hasher: The hasher to use when combining the components
  ///   of this instance.
  @inlinable
  public func hash(into hasher: inout Hasher) {
    switch self {
    case .inRange(let value):
      hasher.combine(0 as Int8)
      hasher.combine(value)
    case .pastEnd:
      hasher.combine(1 as Int8)
    }
  }
}

// FIXME: this should only be conformance to RandomAccessCollection but
// the compiler balks without all 3
extension ClosedRange: Collection, BidirectionalCollection, RandomAccessCollection
where Bound: Strideable, Bound.Stride: SignedInteger
{
  // while a ClosedRange can't be empty, a _slice_ of a ClosedRange can,
  // so ClosedRange can't be its own self-slice unlike Range
  public typealias SubSequence = Slice<ClosedRange<Bound>>

  /// The position of the first element in the range.
  @inlinable
  public var startIndex: Index {
    return .inRange(lowerBound)
  }

  /// The range's "past the end" position---that is, the position one greater
  /// than the last valid subscript argument.
  @inlinable
  public var endIndex: Index {
    return .pastEnd
  }

  @inlinable
  public func index(after i: Index) -> Index {
    switch i {
    case .inRange(let x):
      return x == upperBound
        ? .pastEnd
        : .inRange(x.advanced(by: 1))
    case .pastEnd: 
      _preconditionFailure("Incrementing past end index")
    }
  }

  @inlinable
  public func index(before i: Index) -> Index {
    switch i {
    case .inRange(let x):
      _precondition(x > lowerBound, "Incrementing past start index")
      return .inRange(x.advanced(by: -1))
    case .pastEnd: 
      _precondition(upperBound >= lowerBound, "Incrementing past start index")
      return .inRange(upperBound)
    }
  }

  @inlinable
  public func index(_ i: Index, offsetBy distance: Int) -> Index {
    switch i {
    case .inRange(let x):
      let d = x.distance(to: upperBound)
      if distance <= d {
        let newPosition = x.advanced(by: numericCast(distance))
        _precondition(newPosition >= lowerBound,
          "Advancing past start index")
        return .inRange(newPosition)
      }
      if d - -1 == distance { return .pastEnd }
      _preconditionFailure("Advancing past end index")
    case .pastEnd:
      if distance == 0 {
        return i
      } 
      if distance < 0 {
        return index(.inRange(upperBound), offsetBy: numericCast(distance + 1))
      }
      _preconditionFailure("Advancing past end index")
    }
  }

  @inlinable
  public func distance(from start: Index, to end: Index) -> Int {
    switch (start, end) {
    case let (.inRange(left), .inRange(right)):
      // in range <--> in range
      return numericCast(left.distance(to: right))
    case let (.inRange(left), .pastEnd):
      // in range --> end
      return numericCast(1 + left.distance(to: upperBound))
    case let (.pastEnd, .inRange(right)):
      // in range <-- end
      return numericCast(upperBound.distance(to: right) - 1)
    case (.pastEnd, .pastEnd):
      // end <--> end
      return 0
    }
  }

  /// Accesses the element at specified position.
  ///
  /// You can subscript a collection with any valid index other than the
  /// collection's end index. The end index refers to the position one past
  /// the last element of a collection, so it doesn't correspond with an
  /// element.
  ///
  /// - Parameter position: The position of the element to access. `position`
  ///   must be a valid index of the range, and must not equal the range's end
  ///   index.
  @inlinable
  public subscript(position: Index) -> Bound {
    // FIXME: swift-3-indexing-model: range checks and tests.
    switch position {
    case .inRange(let x): return x
    case .pastEnd: _preconditionFailure("Index out of range")
    }
  }

  @inlinable
  public subscript(bounds: Range<Index>)
    -> Slice<ClosedRange<Bound>> {
    return Slice(base: self, bounds: bounds)
  }

  @inlinable
  public func _customContainsEquatableElement(_ element: Bound) -> Bool? {
    return lowerBound <= element && element <= upperBound
  }

  @inlinable
  public func _customIndexOfEquatableElement(_ element: Bound) -> Index?? {
    return lowerBound <= element && element <= upperBound
              ? .inRange(element) : nil
  }

  @inlinable
  public func _customLastIndexOfEquatableElement(_ element: Bound) -> Index?? {
    // The first and last elements are the same because each element is unique.
    return _customIndexOfEquatableElement(element)
  }
}

extension Comparable {  
  /// Returns a closed range that contains both of its bounds.
  ///
  /// Use the closed range operator (`...`) to create a closed range of any type
  /// that conforms to the `Comparable` protocol. This example creates a
  /// `ClosedRange<Character>` from "a" up to, and including, "z".
  ///
  ///     let lowercase = "a"..."z"
  ///     print(lowercase.contains("z"))
  ///     // Prints "true"
  ///
  /// - Parameters:
  ///   - minimum: The lower bound for the range.
  ///   - maximum: The upper bound for the range.
  ///
  /// - Precondition: `minimum <= maximum`.
  @_transparent
  public static func ... (minimum: Self, maximum: Self) -> ClosedRange<Self> {
    _precondition(
      minimum <= maximum, "Range requires lowerBound <= upperBound")
    return ClosedRange(_uncheckedBounds: (lower: minimum, upper: maximum))
  }
}

extension ClosedRange: Equatable {
  /// Returns a Boolean value indicating whether two ranges are equal.
  ///
  /// Two ranges are equal when they have the same lower and upper bounds.
  ///
  ///     let x = 5...15
  ///     print(x == 5...15)
  ///     // Prints "true"
  ///     print(x == 10...20)
  ///     // Prints "false"
  ///
  /// - Parameters:
  ///   - lhs: A range to compare.
  ///   - rhs: Another range to compare.
  @inlinable
  public static func == (
    lhs: ClosedRange<Bound>, rhs: ClosedRange<Bound>
  ) -> Bool {
    return lhs.lowerBound == rhs.lowerBound && lhs.upperBound == rhs.upperBound
  }
}

extension ClosedRange: Hashable where Bound: Hashable {
  @inlinable
  public func hash(into hasher: inout Hasher) {
    hasher.combine(lowerBound)
    hasher.combine(upperBound)
  }
}

@_unavailableInEmbedded
extension ClosedRange: CustomStringConvertible {
  /// A textual representation of the range.
  @inlinable // trivial-implementation...
  public var description: String {
    return "\(lowerBound)...\(upperBound)"
  }
}

@_unavailableInEmbedded
extension ClosedRange: CustomDebugStringConvertible {
  /// A textual representation of the range, suitable for debugging.
  public var debugDescription: String {
    return "ClosedRange(\(String(reflecting: lowerBound))"
    + "...\(String(reflecting: upperBound)))"
  }
}

#if SWIFT_ENABLE_REFLECTION
extension ClosedRange: CustomReflectable {
  public var customMirror: Mirror {
    return Mirror(
      self, children: ["lowerBound": lowerBound, "upperBound": upperBound])
  }
}
#endif

extension ClosedRange {
  /// Returns a copy of this range clamped to the given limiting range.
  ///
  /// The bounds of the result are always limited to the bounds of `limits`.
  /// For example:
  ///
  ///     let x: ClosedRange = 0...20
  ///     print(x.clamped(to: 10...1000))
  ///     // Prints "10...20"
  ///
  /// If the two ranges do not overlap, the result is a single-element range at
  /// the upper or lower bound of `limits`.
  ///
  ///     let y: ClosedRange = 0...5
  ///     print(y.clamped(to: 10...1000))
  ///     // Prints "10...10"
  ///
  /// - Parameter limits: The range to clamp the bounds of this range.
  /// - Returns: A new range clamped to the bounds of `limits`.
  @inlinable // trivial-implementation
  @inline(__always)
  public func clamped(to limits: ClosedRange) -> ClosedRange {
    let lower =         
      limits.lowerBound > self.lowerBound ? limits.lowerBound
          : limits.upperBound < self.lowerBound ? limits.upperBound
          : self.lowerBound
    let upper =
      limits.upperBound < self.upperBound ? limits.upperBound
          : limits.lowerBound > self.upperBound ? limits.lowerBound
          : self.upperBound
    return ClosedRange(_uncheckedBounds: (lower: lower, upper: upper))
  }
}

extension ClosedRange where Bound: Strideable, Bound.Stride: SignedInteger {
  /// Creates an instance equivalent to the given `Range`.
  ///
  /// - Parameter other: A `Range` to convert to a `ClosedRange` instance.
  ///
  /// An equivalent range must be representable as a closed range.
  /// For example, passing an empty range as `other` triggers a runtime error,
  /// because an empty range cannot be represented by a closed range instance.
  @inlinable
  public init(_ other: Range<Bound>) {
    _precondition(!other.isEmpty, "Can't form an empty closed range")
    let upperBound = other.upperBound.advanced(by: -1)
    self.init(_uncheckedBounds: (lower: other.lowerBound, upper: upperBound))
  }
}

extension ClosedRange {
  @inlinable
  public func overlaps(_ other: ClosedRange<Bound>) -> Bool {
    // Disjoint iff the other range is completely before or after our range.
    // Unlike a `Range`, a `ClosedRange` can *not* be empty, so no check for
    // that case is needed here.
    let isDisjoint = other.upperBound < self.lowerBound
      || self.upperBound < other.lowerBound
    return !isDisjoint
  }

  @inlinable
  public func overlaps(_ other: Range<Bound>) -> Bool {
    return other.overlaps(self)
  }
}

// Note: this is not for compatibility only, it is considered a useful
// shorthand. TODO: Add documentation
public typealias CountableClosedRange<Bound: Strideable> = ClosedRange<Bound>
  where Bound.Stride: SignedInteger

@_unavailableInEmbedded
extension ClosedRange: Decodable where Bound: Decodable {
  public init(from decoder: Decoder) throws {
    var container = try decoder.unkeyedContainer()
    let lowerBound = try container.decode(Bound.self)
    let upperBound = try container.decode(Bound.self)
    guard lowerBound <= upperBound else {
      throw DecodingError.dataCorrupted(
        DecodingError.Context(
          codingPath: decoder.codingPath,
          debugDescription: "Cannot initialize \(ClosedRange.self) with a lowerBound (\(lowerBound)) greater than upperBound (\(upperBound))"))
    }
    self.init(_uncheckedBounds: (lower: lowerBound, upper: upperBound))
  }
}

@_unavailableInEmbedded
extension ClosedRange: Encodable where Bound: Encodable {
  public func encode(to encoder: Encoder) throws {
    var container = encoder.unkeyedContainer()
    try container.encode(self.lowerBound)
    try container.encode(self.upperBound)
  }
}

extension ClosedRange: Sendable where Bound: Sendable { }
extension ClosedRange.Index: Sendable where Bound: Sendable { }