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
|
//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Async Algorithms open source project
//
// Copyright (c) 2022 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
//
//===----------------------------------------------------------------------===//
extension AsyncSequence {
func violatingSpecification(returningPastEndIteration element: Element) -> SpecificationViolatingSequence<Self> {
SpecificationViolatingSequence(self, kind: .producing(element))
}
func violatingSpecification(throwingPastEndIteration error: Error) -> SpecificationViolatingSequence<Self> {
SpecificationViolatingSequence(self, kind: .throwing(error))
}
}
struct SpecificationViolatingSequence<Base: AsyncSequence> {
enum Kind {
case producing(Base.Element)
case throwing(Error)
}
let base: Base
let kind: Kind
init(_ base: Base, kind: Kind) {
self.base = base
self.kind = kind
}
}
extension SpecificationViolatingSequence: AsyncSequence {
typealias Element = Base.Element
struct Iterator: AsyncIteratorProtocol {
var iterator: Base.AsyncIterator
let kind: Kind
var finished = false
var violated = false
mutating func next() async throws -> Element? {
if finished {
if violated {
return nil
}
violated = true
switch kind {
case .producing(let element): return element
case .throwing(let error): throw error
}
}
do {
if let value = try await iterator.next() {
return value
}
finished = true
return nil
} catch {
finished = true
throw error
}
}
}
func makeAsyncIterator() -> Iterator {
Iterator(iterator: base.makeAsyncIterator(), kind: kind)
}
}
|
