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[se-0405] improve fast path

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This commit is contained in:
Guillaume Lessard
2023-12-18 12:34:10 -08:00
parent 148a7e2eff
commit 0ba58de1e1
1 changed files with 2 additions and 7 deletions
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9
stdlib/public/core/StringCreate.swift
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@@ -305,20 +305,15 @@ extension String {
_ input: UnsafeBufferPointer<Encoding.CodeUnit>,
as encoding: Encoding.Type
) -> String? {
fast: // fast-path
if encoding.CodeUnit.self == UInt8.self {
let bytes = _identityCast(input, to: UnsafeBufferPointer<UInt8>.self)
let isASCII: Bool
if encoding.self == UTF8.self {
guard case .success(let info) = validateUTF8(bytes) else { return nil }
isASCII = info.isASCII
return String._uncheckedFromUTF8(bytes, asciiPreScanResult: info.isASCII)
} else if encoding.self == Unicode.ASCII.self {
guard _allASCII(bytes) else { return nil }
isASCII = true
} else {
break fast
return String._uncheckedFromASCII(bytes)
}
return String._uncheckedFromUTF8(bytes, asciiPreScanResult: isASCII)
}
// slow-path