stdlib/public/core/CString.swift - third_party/swift - Git at Google

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 // String interop with C
 //===----------------------------------------------------------------------===//

 import SwiftShims

 extension String {

   /// Creates a new string by copying the null-terminated UTF-8 data referenced
   /// by the given pointer.
   ///
   /// If `cString` contains ill-formed UTF-8 code unit sequences, this
   /// initializer replaces them with the Unicode replacement character
   /// (`"\u{FFFD}"`).
   ///
   /// The following example calls this initializer with pointers to the
   /// contents of two different `CChar` arrays---the first with well-formed
   /// UTF-8 code unit sequences and the second with an ill-formed sequence at
   /// the end.
   ///
   ///     let validUTF8: [CChar] = [67, 97, 102, -61, -87, 0]
   ///     validUTF8.withUnsafeBufferPointer { ptr in
   ///         let s = String(cString: ptr.baseAddress!)
   ///         print(s)
   ///     }
   ///     // Prints "Café"
   ///
   ///     let invalidUTF8: [CChar] = [67, 97, 102, -61, 0]
   ///     invalidUTF8.withUnsafeBufferPointer { ptr in
   ///         let s = String(cString: ptr.baseAddress!)
   ///         print(s)
   ///     }
   ///     // Prints "Caf�"
   ///
   /// - Parameter cString: A pointer to a null-terminated UTF-8 code sequence.
   public init(cString: UnsafePointer<CChar>) {
     let len = UTF8._nullCodeUnitOffset(in: cString)
     self = String._fromUTF8Repairing(
       UnsafeBufferPointer(start: cString._asUInt8, count: len)).0
   }

   /// Creates a new string by copying the null-terminated UTF-8 data referenced
   /// by the given pointer.
   ///
   /// This is identical to init(cString: UnsafePointer<CChar> but operates on an
   /// unsigned sequence of bytes.
   public init(cString: UnsafePointer<UInt8>) {
     let len = UTF8._nullCodeUnitOffset(in: cString)
     self = String._fromUTF8Repairing(
       UnsafeBufferPointer(start: cString, count: len)).0
   }

   /// Creates a new string by copying and validating the null-terminated UTF-8
   /// data referenced by the given pointer.
   ///
   /// This initializer does not try to repair ill-formed UTF-8 code unit
   /// sequences. If any are found, the result of the initializer is `nil`.
   ///
   /// The following example calls this initializer with pointers to the
   /// contents of two different `CChar` arrays---the first with well-formed
   /// UTF-8 code unit sequences and the second with an ill-formed sequence at
   /// the end.
   ///
   ///     let validUTF8: [CChar] = [67, 97, 102, -61, -87, 0]
   ///     validUTF8.withUnsafeBufferPointer { ptr in
   ///         let s = String(validatingUTF8: ptr.baseAddress!)
   ///         print(s)
   ///     }
   ///     // Prints "Optional(Café)"
   ///
   ///     let invalidUTF8: [CChar] = [67, 97, 102, -61, 0]
   ///     invalidUTF8.withUnsafeBufferPointer { ptr in
   ///         let s = String(validatingUTF8: ptr.baseAddress!)
   ///         print(s)
   ///     }
   ///     // Prints "nil"
   ///
   /// - Parameter cString: A pointer to a null-terminated UTF-8 code sequence.
   public init?(validatingUTF8 cString: UnsafePointer<CChar>) {
     let len = UTF8._nullCodeUnitOffset(in: cString)
     guard let str = String._tryFromUTF8(
       UnsafeBufferPointer(start: cString._asUInt8, count: len))
     else { return nil }

     self = str
   }

   /// Creates a new string by copying the null-terminated data referenced by
   /// the given pointer using the specified encoding.
   ///
   /// When you pass `true` as `isRepairing`, this method replaces ill-formed
   /// sequences with the Unicode replacement character (`"\u{FFFD}"`);
   /// otherwise, an ill-formed sequence causes this method to stop decoding
   /// and return `nil`.
   ///
   /// The following example calls this method with pointers to the contents of
   /// two different `CChar` arrays---the first with well-formed UTF-8 code
   /// unit sequences and the second with an ill-formed sequence at the end.
   ///
   ///     let validUTF8: [UInt8] = [67, 97, 102, 195, 169, 0]
   ///     validUTF8.withUnsafeBufferPointer { ptr in
   ///         let s = String.decodeCString(ptr.baseAddress,
   ///                                      as: UTF8.self,
   ///                                      repairingInvalidCodeUnits: true)
   ///         print(s)
   ///     }
   ///     // Prints "Optional((Café, false))"
   ///
   ///     let invalidUTF8: [UInt8] = [67, 97, 102, 195, 0]
   ///     invalidUTF8.withUnsafeBufferPointer { ptr in
   ///         let s = String.decodeCString(ptr.baseAddress,
   ///                                      as: UTF8.self,
   ///                                      repairingInvalidCodeUnits: true)
   ///         print(s)
   ///     }
   ///     // Prints "Optional((Caf�, true))"
   ///
   /// - Parameters:
   ///   - cString: A pointer to a null-terminated code sequence encoded in
   ///     `encoding`.
   ///   - encoding: The Unicode encoding of the data referenced by `cString`.
   ///   - isRepairing: Pass `true` to create a new string, even when the data
   ///     referenced by `cString` contains ill-formed sequences. Ill-formed
   ///     sequences are replaced with the Unicode replacement character
   ///     (`"\u{FFFD}"`). Pass `false` to interrupt the creation of the new
   ///     string if an ill-formed sequence is detected.
   /// - Returns: A tuple with the new string and a Boolean value that indicates
   ///   whether any repairs were made. If `isRepairing` is `false` and an
   ///   ill-formed sequence is detected, this method returns `nil`.
   @_specialize(where Encoding == Unicode.UTF8)
   @_specialize(where Encoding == Unicode.UTF16)
   @inlinable // Fold away specializations
   public static func decodeCString<Encoding : _UnicodeEncoding>(
     _ cString: UnsafePointer<Encoding.CodeUnit>?,
     as encoding: Encoding.Type,
     repairingInvalidCodeUnits isRepairing: Bool = true
   ) -> (result: String, repairsMade: Bool)? {
     guard let cPtr = cString else { return nil }

     if _fastPath(encoding == Unicode.UTF8.self) {
       let ptr = UnsafeRawPointer(cPtr).assumingMemoryBound(to: UInt8.self)
       let len = UTF8._nullCodeUnitOffset(in: ptr)
       let codeUnits = UnsafeBufferPointer(start: ptr, count: len)
       if isRepairing {
         return String._fromUTF8Repairing(codeUnits)
       } else {
         guard let str = String._tryFromUTF8(codeUnits) else { return nil }
         return (str, false)
       }
     }

     var end = cPtr
     while end.pointee != 0 { end += 1 }
     let len = end - cPtr
     let codeUnits = UnsafeBufferPointer(start: cPtr, count: len)
     return String._fromCodeUnits(
       codeUnits, encoding: encoding, repair: isRepairing)
   }
   /// Creates a string from the null-terminated sequence of bytes at the given
   /// pointer.
   ///
   /// - Parameters:
   ///   - nullTerminatedCodeUnits: A pointer to a sequence of contiguous code
   ///     units in the encoding specified in `sourceEncoding`, ending just
   ///     before the first zero code unit.
   ///   - sourceEncoding: The encoding in which the code units should be
   ///     interpreted.
   @_specialize(where Encoding == Unicode.UTF8)
   @_specialize(where Encoding == Unicode.UTF16)
   @inlinable // Fold away specializations
   public init<Encoding: Unicode.Encoding>(
     decodingCString ptr: UnsafePointer<Encoding.CodeUnit>,
     as sourceEncoding: Encoding.Type
   ) {
     self = String.decodeCString(ptr, as: sourceEncoding)!.0
   }
 }

 extension UnsafePointer where Pointee == UInt8 {
   @inlinable
   internal var _asCChar: UnsafePointer<CChar> {
     @inline(__always) get {
       return UnsafeRawPointer(self).assumingMemoryBound(to: CChar.self)
     }
   }
 }
 extension UnsafePointer where Pointee == CChar {
   @inlinable
   internal var _asUInt8: UnsafePointer<UInt8> {
     @inline(__always) get {
       return UnsafeRawPointer(self).assumingMemoryBound(to: UInt8.self)
     }
   }
 }
	//===----------------------------------------------------------------------===//
	//
	// 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
	//
	//===----------------------------------------------------------------------===//
	// String interop with C
	//===----------------------------------------------------------------------===//

	import SwiftShims

	extension String {

	/// Creates a new string by copying the null-terminated UTF-8 data referenced
	/// by the given pointer.
	///
	/// If `cString` contains ill-formed UTF-8 code unit sequences, this
	/// initializer replaces them with the Unicode replacement character
	/// (`"\u{FFFD}"`).
	///
	/// The following example calls this initializer with pointers to the
	/// contents of two different `CChar` arrays---the first with well-formed
	/// UTF-8 code unit sequences and the second with an ill-formed sequence at
	/// the end.
	///
	/// let validUTF8: [CChar] = [67, 97, 102, -61, -87, 0]
	/// validUTF8.withUnsafeBufferPointer { ptr in
	/// let s = String(cString: ptr.baseAddress!)
	/// print(s)
	/// }
	/// // Prints "Café"
	///
	/// let invalidUTF8: [CChar] = [67, 97, 102, -61, 0]
	/// invalidUTF8.withUnsafeBufferPointer { ptr in
	/// let s = String(cString: ptr.baseAddress!)
	/// print(s)
	/// }
	/// // Prints "Caf�"
	///
	/// - Parameter cString: A pointer to a null-terminated UTF-8 code sequence.
	public init(cString: UnsafePointer<CChar>) {
	let len = UTF8._nullCodeUnitOffset(in: cString)
	self = String._fromUTF8Repairing(
	UnsafeBufferPointer(start: cString._asUInt8, count: len)).0
	}

	/// Creates a new string by copying the null-terminated UTF-8 data referenced
	/// by the given pointer.
	///
	/// This is identical to init(cString: UnsafePointer<CChar> but operates on an
	/// unsigned sequence of bytes.
	public init(cString: UnsafePointer<UInt8>) {
	let len = UTF8._nullCodeUnitOffset(in: cString)
	self = String._fromUTF8Repairing(
	UnsafeBufferPointer(start: cString, count: len)).0
	}

	/// Creates a new string by copying and validating the null-terminated UTF-8
	/// data referenced by the given pointer.
	///
	/// This initializer does not try to repair ill-formed UTF-8 code unit
	/// sequences. If any are found, the result of the initializer is `nil`.
	///
	/// The following example calls this initializer with pointers to the
	/// contents of two different `CChar` arrays---the first with well-formed
	/// UTF-8 code unit sequences and the second with an ill-formed sequence at
	/// the end.
	///
	/// let validUTF8: [CChar] = [67, 97, 102, -61, -87, 0]
	/// validUTF8.withUnsafeBufferPointer { ptr in
	/// let s = String(validatingUTF8: ptr.baseAddress!)
	/// print(s)
	/// }
	/// // Prints "Optional(Café)"
	///
	/// let invalidUTF8: [CChar] = [67, 97, 102, -61, 0]
	/// invalidUTF8.withUnsafeBufferPointer { ptr in
	/// let s = String(validatingUTF8: ptr.baseAddress!)
	/// print(s)
	/// }
	/// // Prints "nil"
	///
	/// - Parameter cString: A pointer to a null-terminated UTF-8 code sequence.
	public init?(validatingUTF8 cString: UnsafePointer<CChar>) {
	let len = UTF8._nullCodeUnitOffset(in: cString)
	guard let str = String._tryFromUTF8(
	UnsafeBufferPointer(start: cString._asUInt8, count: len))
	else { return nil }

	self = str
	}

	/// Creates a new string by copying the null-terminated data referenced by
	/// the given pointer using the specified encoding.
	///
	/// When you pass `true` as `isRepairing`, this method replaces ill-formed
	/// sequences with the Unicode replacement character (`"\u{FFFD}"`);
	/// otherwise, an ill-formed sequence causes this method to stop decoding
	/// and return `nil`.
	///
	/// The following example calls this method with pointers to the contents of
	/// two different `CChar` arrays---the first with well-formed UTF-8 code
	/// unit sequences and the second with an ill-formed sequence at the end.
	///
	/// let validUTF8: [UInt8] = [67, 97, 102, 195, 169, 0]
	/// validUTF8.withUnsafeBufferPointer { ptr in
	/// let s = String.decodeCString(ptr.baseAddress,
	/// as: UTF8.self,
	/// repairingInvalidCodeUnits: true)
	/// print(s)
	/// }
	/// // Prints "Optional((Café, false))"
	///
	/// let invalidUTF8: [UInt8] = [67, 97, 102, 195, 0]
	/// invalidUTF8.withUnsafeBufferPointer { ptr in
	/// let s = String.decodeCString(ptr.baseAddress,
	/// as: UTF8.self,
	/// repairingInvalidCodeUnits: true)
	/// print(s)
	/// }
	/// // Prints "Optional((Caf�, true))"
	///
	/// - Parameters:
	/// - cString: A pointer to a null-terminated code sequence encoded in
	/// `encoding`.
	/// - encoding: The Unicode encoding of the data referenced by `cString`.
	/// - isRepairing: Pass `true` to create a new string, even when the data
	/// referenced by `cString` contains ill-formed sequences. Ill-formed
	/// sequences are replaced with the Unicode replacement character
	/// (`"\u{FFFD}"`). Pass `false` to interrupt the creation of the new
	/// string if an ill-formed sequence is detected.
	/// - Returns: A tuple with the new string and a Boolean value that indicates
	/// whether any repairs were made. If `isRepairing` is `false` and an
	/// ill-formed sequence is detected, this method returns `nil`.
	@_specialize(where Encoding == Unicode.UTF8)
	@_specialize(where Encoding == Unicode.UTF16)
	@inlinable // Fold away specializations
	public static func decodeCString<Encoding : _UnicodeEncoding>(
	_ cString: UnsafePointer<Encoding.CodeUnit>?,
	as encoding: Encoding.Type,
	repairingInvalidCodeUnits isRepairing: Bool = true
	) -> (result: String, repairsMade: Bool)? {
	guard let cPtr = cString else { return nil }

	if _fastPath(encoding == Unicode.UTF8.self) {
	let ptr = UnsafeRawPointer(cPtr).assumingMemoryBound(to: UInt8.self)
	let len = UTF8._nullCodeUnitOffset(in: ptr)
	let codeUnits = UnsafeBufferPointer(start: ptr, count: len)
	if isRepairing {
	return String._fromUTF8Repairing(codeUnits)
	} else {
	guard let str = String._tryFromUTF8(codeUnits) else { return nil }
	return (str, false)
	}
	}

	var end = cPtr
	while end.pointee != 0 { end += 1 }
	let len = end - cPtr
	let codeUnits = UnsafeBufferPointer(start: cPtr, count: len)
	return String._fromCodeUnits(
	codeUnits, encoding: encoding, repair: isRepairing)
	}
	/// Creates a string from the null-terminated sequence of bytes at the given
	/// pointer.
	///
	/// - Parameters:
	/// - nullTerminatedCodeUnits: A pointer to a sequence of contiguous code
	/// units in the encoding specified in `sourceEncoding`, ending just
	/// before the first zero code unit.
	/// - sourceEncoding: The encoding in which the code units should be
	/// interpreted.
	@_specialize(where Encoding == Unicode.UTF8)
	@_specialize(where Encoding == Unicode.UTF16)
	@inlinable // Fold away specializations
	public init<Encoding: Unicode.Encoding>(
	decodingCString ptr: UnsafePointer<Encoding.CodeUnit>,
	as sourceEncoding: Encoding.Type
	) {
	self = String.decodeCString(ptr, as: sourceEncoding)!.0
	}
	}

	extension UnsafePointer where Pointee == UInt8 {
	@inlinable
	internal var _asCChar: UnsafePointer<CChar> {
	@inline(__always) get {
	return UnsafeRawPointer(self).assumingMemoryBound(to: CChar.self)
	}
	}
	}
	extension UnsafePointer where Pointee == CChar {
	@inlinable
	internal var _asUInt8: UnsafePointer<UInt8> {
	@inline(__always) get {
	return UnsafeRawPointer(self).assumingMemoryBound(to: UInt8.self)
	}
	}
	}