stdlib/public/SDK/Foundation/String.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
//
//===----------------------------------------------------------------------===//

@_exported import Foundation // Clang module

//===----------------------------------------------------------------------===//
// New Strings
//===----------------------------------------------------------------------===//

//
// Conversion from NSString to Swift's native representation
//

extension String {
  public init(_ cocoaString: NSString) {
    self = String(_cocoaString: cocoaString)
  }
}

extension String : _ObjectiveCBridgeable {
  @_semantics("convertToObjectiveC")
  public func _bridgeToObjectiveC() -> NSString {
    // This method should not do anything extra except calling into the
    // implementation inside core.  (These two entry points should be
    // equivalent.)
    return unsafeBitCast(_bridgeToObjectiveCImpl() as AnyObject, to: NSString.self)
  }

  public static func _forceBridgeFromObjectiveC(
    _ x: NSString,
    result: inout String?
  ) {
    result = String(x)
  }

  public static func _conditionallyBridgeFromObjectiveC(
    _ x: NSString,
    result: inout String?
  ) -> Bool {
    self._forceBridgeFromObjectiveC(x, result: &result)
    return result != nil
  }

  public static func _unconditionallyBridgeFromObjectiveC(
    _ source: NSString?
  ) -> String {
    // `nil` has historically been used as a stand-in for an empty
    // string; map it to an empty string.
    if _slowPath(source == nil) { return String() }
    return String(source!)
  }
}

extension Substring : _ObjectiveCBridgeable {
  @_semantics("convertToObjectiveC")
  public func _bridgeToObjectiveC() -> NSString {
    return String(self)._bridgeToObjectiveC()
  }

  public static func _forceBridgeFromObjectiveC(
    _ x: NSString,
    result: inout Substring?
  ) {
    let s = String(x)
    result = Substring(_base: s, s.startIndex ..< s.endIndex)
  }

  public static func _conditionallyBridgeFromObjectiveC(
    _ x: NSString,
    result: inout Substring?
  ) -> Bool {
    self._forceBridgeFromObjectiveC(x, result: &result)
    return result != nil
  }

  public static func _unconditionallyBridgeFromObjectiveC(
    _ source: NSString?
  ) -> Substring {
    // `nil` has historically been used as a stand-in for an empty
    // string; map it to an empty substring.
    if _slowPath(source == nil) { return Substring() }
    let s = String(source!)
    return Substring(_base: s, s.startIndex ..< s.endIndex)
  }
}

extension String: CVarArg {}