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.
   @_inlineable // FIXME(sil-serialize-all)
   public init(cString: UnsafePointer<CChar>) {
     let len = UTF8._nullCodeUnitOffset(in: cString)
     let (result, _) = cString.withMemoryRebound(to: UInt8.self, capacity: len) {
       _decodeCString(
         $0, as: UTF8.self, length: len, repairingInvalidCodeUnits: true)!
     }
     self = result
   }

   /// 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.
   @_inlineable // FIXME(sil-serialize-all)
   public init(cString: UnsafePointer<UInt8>) {
     self = String.decodeCString(
       cString, as: UTF8.self, repairingInvalidCodeUnits: true)!.result
   }

   /// 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.
   @_inlineable // FIXME(sil-serialize-all)
   public init?(validatingUTF8 cString: UnsafePointer<CChar>) {
     let len = UTF8._nullCodeUnitOffset(in: cString)
     guard let (result, _) =
     cString.withMemoryRebound(to: UInt8.self, capacity: len, {
         _decodeCString($0, as: UTF8.self, length: len,
           repairingInvalidCodeUnits: false)
       })
     else {
       return nil
     }
     self = result
   }

   /// 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`.
   @_inlineable // FIXME(sil-serialize-all)
   public static func decodeCString<Encoding : _UnicodeEncoding>(
     _ cString: UnsafePointer<Encoding.CodeUnit>?,
     as encoding: Encoding.Type,
     repairingInvalidCodeUnits isRepairing: Bool = true)
       -> (result: String, repairsMade: Bool)? {

     guard let cString = cString else {
       return nil
     }
     var end = cString
     while end.pointee != 0 { end += 1 }
     let len = end - cString
     return _decodeCString(
       cString, as: encoding, length: len,
       repairingInvalidCodeUnits: isRepairing)
   }

 }

 /// From a non-`nil` `UnsafePointer` to a null-terminated string
 /// with possibly-transient lifetime, create a null-terminated array of 'C' char.
 /// Returns `nil` if passed a null pointer.
 @_inlineable // FIXME(sil-serialize-all)
 public func _persistCString(_ p: UnsafePointer<CChar>?) -> [CChar]? {
   guard let s = p else {
     return nil
   }
   let count = Int(_stdlib_strlen(s))
   var result = [CChar](repeating: 0, count: count + 1)
   for i in 0..<count {
     result[i] = s[i]
   }
   return result
 }

 /// Creates a new string by copying the null-terminated data referenced by
 /// the given pointer using the specified encoding.
 ///
 /// This internal helper takes the string length as an argument.
 @_inlineable // FIXME(sil-serialize-all)
 @_versioned // FIXME(sil-serialize-all)
 internal func _decodeCString<Encoding : _UnicodeEncoding>(
   _ cString: UnsafePointer<Encoding.CodeUnit>,
   as encoding: Encoding.Type, length: Int,
   repairingInvalidCodeUnits isRepairing: Bool = true)
 -> (result: String, repairsMade: Bool)? {

   let buffer = UnsafeBufferPointer<Encoding.CodeUnit>(
     start: cString, count: length)

   let (guts, hadError) = _StringGuts.fromCodeUnits(
     buffer, encoding: encoding, repairIllFormedSequences: isRepairing)
   return guts.map { (result: String($0), repairsMade: hadError) }
 }
	//===----------------------------------------------------------------------===//
	//
	// 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.
	@_inlineable // FIXME(sil-serialize-all)
	public init(cString: UnsafePointer<CChar>) {
	let len = UTF8._nullCodeUnitOffset(in: cString)
	let (result, _) = cString.withMemoryRebound(to: UInt8.self, capacity: len) {
	_decodeCString(
	$0, as: UTF8.self, length: len, repairingInvalidCodeUnits: true)!
	}
	self = result
	}

	/// 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.
	@_inlineable // FIXME(sil-serialize-all)
	public init(cString: UnsafePointer<UInt8>) {
	self = String.decodeCString(
	cString, as: UTF8.self, repairingInvalidCodeUnits: true)!.result
	}

	/// 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.
	@_inlineable // FIXME(sil-serialize-all)
	public init?(validatingUTF8 cString: UnsafePointer<CChar>) {
	let len = UTF8._nullCodeUnitOffset(in: cString)
	guard let (result, _) =
	cString.withMemoryRebound(to: UInt8.self, capacity: len, {
	_decodeCString($0, as: UTF8.self, length: len,
	repairingInvalidCodeUnits: false)
	})
	else {
	return nil
	}
	self = result
	}

	/// 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`.
	@_inlineable // FIXME(sil-serialize-all)
	public static func decodeCString<Encoding : _UnicodeEncoding>(
	_ cString: UnsafePointer<Encoding.CodeUnit>?,
	as encoding: Encoding.Type,
	repairingInvalidCodeUnits isRepairing: Bool = true)
	-> (result: String, repairsMade: Bool)? {

	guard let cString = cString else {
	return nil
	}
	var end = cString
	while end.pointee != 0 { end += 1 }
	let len = end - cString
	return _decodeCString(
	cString, as: encoding, length: len,
	repairingInvalidCodeUnits: isRepairing)
	}

	}

	/// From a non-`nil` `UnsafePointer` to a null-terminated string
	/// with possibly-transient lifetime, create a null-terminated array of 'C' char.
	/// Returns `nil` if passed a null pointer.
	@_inlineable // FIXME(sil-serialize-all)
	public func _persistCString(_ p: UnsafePointer<CChar>?) -> [CChar]? {
	guard let s = p else {
	return nil
	}
	let count = Int(_stdlib_strlen(s))
	var result = [CChar](repeating: 0, count: count + 1)
	for i in 0..<count {
	result[i] = s[i]
	}
	return result
	}

	/// Creates a new string by copying the null-terminated data referenced by
	/// the given pointer using the specified encoding.
	///
	/// This internal helper takes the string length as an argument.
	@_inlineable // FIXME(sil-serialize-all)
	@_versioned // FIXME(sil-serialize-all)
	internal func _decodeCString<Encoding : _UnicodeEncoding>(
	_ cString: UnsafePointer<Encoding.CodeUnit>,
	as encoding: Encoding.Type, length: Int,
	repairingInvalidCodeUnits isRepairing: Bool = true)
	-> (result: String, repairsMade: Bool)? {

	let buffer = UnsafeBufferPointer<Encoding.CodeUnit>(
	start: cString, count: length)

	let (guts, hadError) = _StringGuts.fromCodeUnits(
	buffer, encoding: encoding, repairIllFormedSequences: isRepairing)
	return guts.map { (result: String($0), repairsMade: hadError) }
	}