| //===--- ASCII.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 |
| // |
| //===----------------------------------------------------------------------===// |
| extension Unicode { |
| @_frozen |
| public enum ASCII {} |
| } |
| |
| extension Unicode.ASCII : Unicode.Encoding { |
| public typealias CodeUnit = UInt8 |
| public typealias EncodedScalar = CollectionOfOne<CodeUnit> |
| |
| @inlinable |
| public static var encodedReplacementCharacter : EncodedScalar { |
| return EncodedScalar(0x1a) // U+001A SUBSTITUTE; best we can do for ASCII |
| } |
| |
| /// Returns whether the given code unit represents an ASCII scalar |
| @_alwaysEmitIntoClient |
| public static func isASCII(_ x: CodeUnit) -> Bool { return UTF8.isASCII(x) } |
| |
| @inline(__always) |
| @inlinable |
| public static func _isScalar(_ x: CodeUnit) -> Bool { |
| return true |
| } |
| |
| @inline(__always) |
| @inlinable |
| public static func decode(_ source: EncodedScalar) -> Unicode.Scalar { |
| return Unicode.Scalar(_unchecked: UInt32( |
| source.first._unsafelyUnwrappedUnchecked)) |
| } |
| |
| @inline(__always) |
| @inlinable |
| public static func encode( |
| _ source: Unicode.Scalar |
| ) -> EncodedScalar? { |
| guard source.value < (1&<<7) else { return nil } |
| return EncodedScalar(UInt8(truncatingIfNeeded: source.value)) |
| } |
| |
| @inline(__always) |
| @inlinable |
| public static func transcode<FromEncoding : Unicode.Encoding>( |
| _ content: FromEncoding.EncodedScalar, from _: FromEncoding.Type |
| ) -> EncodedScalar? { |
| if _fastPath(FromEncoding.self == UTF16.self) { |
| let c = _identityCast(content, to: UTF16.EncodedScalar.self) |
| guard (c._storage & 0xFF80 == 0) else { return nil } |
| return EncodedScalar(CodeUnit(c._storage & 0x7f)) |
| } |
| else if _fastPath(FromEncoding.self == UTF8.self) { |
| let c = _identityCast(content, to: UTF8.EncodedScalar.self) |
| let first = c.first.unsafelyUnwrapped |
| guard (first < 0x80) else { return nil } |
| return EncodedScalar(CodeUnit(first)) |
| } |
| return encode(FromEncoding.decode(content)) |
| } |
| |
| @_fixed_layout |
| public struct Parser { |
| @inlinable |
| public init() { } |
| } |
| |
| public typealias ForwardParser = Parser |
| public typealias ReverseParser = Parser |
| } |
| |
| extension Unicode.ASCII.Parser : Unicode.Parser { |
| public typealias Encoding = Unicode.ASCII |
| |
| /// Parses a single Unicode scalar value from `input`. |
| @inlinable |
| public mutating func parseScalar<I : IteratorProtocol>( |
| from input: inout I |
| ) -> Unicode.ParseResult<Encoding.EncodedScalar> |
| where I.Element == Encoding.CodeUnit { |
| let n = input.next() |
| if _fastPath(n != nil), let x = n { |
| guard _fastPath(Int8(truncatingIfNeeded: x) >= 0) |
| else { return .error(length: 1) } |
| return .valid(Unicode.ASCII.EncodedScalar(x)) |
| } |
| return .emptyInput |
| } |
| } |