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f4610e1638
...to make room for a more useful encode/transcode that inject replacement characters when encoding fails.
64 lines
2.6 KiB
Swift
64 lines
2.6 KiB
Swift
//===--- UnicodeEncoding.swift --------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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public protocol _UnicodeEncoding {
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/// The basic unit of encoding
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associatedtype CodeUnit : UnsignedInteger, FixedWidthInteger
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/// A valid scalar value as represented in this encoding
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associatedtype EncodedScalar : BidirectionalCollection
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where EncodedScalar.Iterator.Element == CodeUnit
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/// The replacement character U+FFFD as represented in this encoding
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static var encodedReplacementCharacter : EncodedScalar { get }
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/// Converts from encoded to encoding-independent representation
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static func decode(_ content: EncodedScalar) -> UnicodeScalar
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/// Converts from encoding-independent to encoded representation, returning
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/// `nil` if the scalar can't be represented in this encoding.
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static func encodeIfRepresentable(_ content: UnicodeScalar) -> EncodedScalar?
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/// Converts a scalar from another encoding's representation, returning
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/// `nil` if the scalar can't be represented in this encoding.
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static func transcodeIfRepresentable<FromEncoding : UnicodeEncoding>(
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_ content: FromEncoding.EncodedScalar, from _: FromEncoding.Type
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) -> EncodedScalar?
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associatedtype ForwardParser : UnicodeParser
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associatedtype ReverseParser : UnicodeParser
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//===--------------------------------------------------------------------===//
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// FIXME: this requirement shouldn't be here and is mitigated by the default
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// implementation below. Compiler bugs prevent it from being expressed in an
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// intermediate, underscored protocol.
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/// Returns true if `x` only appears in this encoding as the representation of
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/// a complete scalar value.
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static func _isScalar(_ x: CodeUnit) -> Bool
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}
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extension _UnicodeEncoding {
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// See note on declaration of requirement, above
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public static func _isScalar(_ x: CodeUnit) -> Bool { return false }
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}
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public protocol UnicodeEncoding : _UnicodeEncoding
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where ForwardParser.Encoding == Self, ReverseParser.Encoding == Self {}
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extension _UnicodeEncoding {
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public static func transcodeIfRepresentable<FromEncoding : UnicodeEncoding>(
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_ content: FromEncoding.EncodedScalar, from _: FromEncoding.Type
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) -> EncodedScalar? {
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return encode(FromEncoding.decode(content))
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}
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}
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