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
|
//===--- Interval.swift ---------------------------------------*- swift -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2020 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 not-particularly-clever floating-point iterval that is iterable for the
// purposes of testing.
public struct Interval<Element>: Sequence where Element: FloatingPoint {
let lower: Element
let upper: Element
public init(from: Element, through: Element) {
precondition(from <= through)
lower = from
upper = through
}
public init(from: Element, to: Element) {
self.init(from: from, through: to.nextDown)
}
public func makeIterator() -> Iterator {
Iterator(self)
}
public struct Iterator: IteratorProtocol {
let interval: Interval
var nextOutput: Element?
init(_ interval: Interval) {
self.interval = interval
self.nextOutput = interval.lower
}
public mutating func next() -> Element? {
let result = nextOutput
if nextOutput == interval.upper { nextOutput = nil }
else { nextOutput = nextOutput?.nextUp }
return result
}
}
}
|
