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
|
protocol ByteStream: Stream where Element == UInt8 {}
final class StaticByteStream: ByteStream {
let bytes: [UInt8]
var currentIndex: Int
init(bytes: [UInt8]) {
self.bytes = bytes
currentIndex = bytes.startIndex
}
@discardableResult
func consumeAny() throws -> UInt8 {
guard bytes.indices.contains(currentIndex) else {
throw StreamError<Element>.unexpectedEnd(expected: nil)
}
let consumed = bytes[currentIndex]
currentIndex = bytes.index(after: currentIndex)
return consumed
}
@discardableResult
func consume(_ expected: Set<UInt8>) throws -> UInt8 {
guard bytes.indices.contains(currentIndex) else {
throw StreamError<Element>.unexpectedEnd(expected: Set(expected))
}
let consumed = bytes[currentIndex]
guard expected.contains(consumed) else {
throw StreamError<Element>.unexpected(consumed, index: currentIndex, expected: Set(expected))
}
currentIndex = bytes.index(after: currentIndex)
return consumed
}
func consume(count: Int) throws -> ArraySlice<UInt8> {
let updatedIndex = currentIndex + count
guard bytes.indices.contains(updatedIndex - 1) else {
throw StreamError<Element>.unexpectedEnd(expected: nil)
}
defer { currentIndex = updatedIndex }
return bytes[currentIndex..<updatedIndex]
}
func peek() -> UInt8? {
guard bytes.indices.contains(currentIndex) else {
return nil
}
return bytes[currentIndex]
}
}
|
