用 Swift 来写命令行程序

作者：Joe， 原文链接 ，原文日期：2015-12-28

译者： aaaron7 ；校对： Cee ；定稿：littledogboy

import Foundation
import Glibc
 
let interpreter = CommandInterpreter()
let translator  = Translator()
 
// Listen for events to translate
nc.addObserverForName(INPUT_NOTIFICATION, object:nil, queue:nil) {
  (_) in
  let tc = translationCommand
  translator.translate(tc.text, from:tc.from, to:tc.to){
    translation, error in
    guard error == nil && translation != nil else {
      print("Translation failure:  /(error!.code)")
      return
    }
    print(translation!)
  }
}
 
interpreter.start()
 
select(0, nil, nil, nil, nil)

// Import statements
import Foundation
import Glibc
 
// Enumerations
enum CommandType {
case None
case Translate
case SetFrom
case SetTo
case Quit
}
 
// Structs
struct Command {
  var type:CommandType
  var data:String
}
 
// Classes
class CommandInterpreter {
 
  // Read-only computed property
  var prompt:String {
    return "/(translationCommand.from)->/(translationCommand.to)"
  }
 
  // Class constant
  let delim:Character = "/n"
 
  init() {
  }
 
  func start() {
    let readThread = NSThread(){
      var input:String    = ""
      
      print("To set input language, type 'from LANG'")
      print("To set output language, type 'to LANG'")
      print("Type 'quit' to exit")
      self.displayPrompt()
 
      while true {
        let c = Character(UnicodeScalar(UInt32(fgetc(stdin))))
        if c == self.delim {
          let command = self.parseInput(input)
          self.doCommand(command)
          input = "" // Clear input
          self.displayPrompt()
        } else {
          input.append(c)
        }
      }
    }
    
    readThread.start()
  }
 
  func displayPrompt() {
    print("/(self.prompt):  ", terminator:"")
  }
 
  func parseInput(input:String) -> Command {
    var commandType:CommandType
    var commandData:String = ""
    
    // Splitting a string
    let tokens = input.characters.split{$0 == " "}.map(String.init)
 
    // guard statement to validate that there are tokens
    guard tokens.count > 0 else {
      return Command(type:CommandType.None, data:"")
    }
 
    switch tokens[0] {
    case "quit":
      commandType = .Quit
    case "from":
      commandType = .SetFrom
      commandData = tokens[1]
    case "to":
      commandType = .SetTo
      commandData = tokens[1]
    default:
      commandType = .Translate
      commandData = input
    }
    return Command(type:commandType,data:commandData)
  }
 
  func doCommand(command:Command) {
    switch command.type {
    case .Quit:
      exit(0)
    case .SetFrom:
      translationCommand.from = command.data
    case .SetTo:
      translationCommand.to   = command.data
    case .Translate:
      translationCommand.text = command.data
      nc.postNotificationName(INPUT_NOTIFICATION, object:nil)   
    case .None:
      break
    }
  }
}

// Listen for events to translate
nc.addObserverForName(INPUT_NOTIFICATION, object:nil, queue:nil) {
  (_) in
  let tc = translationCommand
  translator.translate(tc.text, from:tc.from, to:tc.to){
    translation, error in
    guard error == nil && translation != nil else {
      print("Translation failure:  /(error!.code)")
      return
    }
    print(translation!)
  }
}

import Glibc
import Foundation
import CcURL
import CJSONC
 
class Translator {
 
  let BUFSIZE = 1024
 
  init() {
  }
 
  func translate(text:String, from:String, to:String,
                        completion:(translation:String?, error:NSError?) -> Void) {
 
    let curl = curl_easy_init()
 
    guard curl != nil else {
      completion(translation:nil,
                 error:NSError(domain:"translator", code:1, userInfo:nil))
      return
    }
 
    let escapedText = curl_easy_escape(curl, text, Int32(strlen(text)))
 
    guard escapedText != nil else {
      completion(translation:nil,
                 error:NSError(domain:"translator", code:2, userInfo:nil))
      return
    }
    
    let langPair = from + "%7c" + to
    let wgetCommand = "wget -qO- http://api.mymemory.translated.net/get//?q//=" + String.fromCString(escapedText)! + "//&langpair//=" + langPair
    
    let pp      = popen(wgetCommand, "r")
    var buf     = [CChar](count:BUFSIZE, repeatedValue:CChar(0))
    
    var response:String = ""
    while fgets(&buf, Int32(BUFSIZE), pp) != nil {
      response = response + String.fromCString(buf)!
    }
    
    let translation = getTranslatedText(response)
 
    guard translation.error == nil else {
      completion(translation:nil, error:translation.error)
      return
    }
 
    completion(translation:translation.translation, error:nil)
  }
 
  private func getTranslatedText(jsonString:String) -> (error:NSError?, translation:String?) {
 
    let obj = json_tokener_parse(jsonString)
 
    guard obj != nil else {
      return (NSError(domain:"translator", code:3, userInfo:nil),
             nil)
    }
 
    let responseData = json_object_object_get(obj, "responseData")
 
    guard responseData != nil else {
      return (NSError(domain:"translator", code:3, userInfo:nil),
              nil)
    }
 
    let translatedTextObj = json_object_object_get(responseData,
                                                   "translatedText")
 
    guard translatedTextObj != nil else {
      return (NSError(domain:"translator", code:3, userInfo:nil),
              nil)
    }
 
    let translatedTextStr = json_object_get_string(translatedTextObj)
 
    return (nil, String.fromCString(translatedTextStr)!)
           
  }
 
}

import Foundation
 
let INPUT_NOTIFICATION   = "InputNotification"
let nc = NSNotificationCenter.defaultCenter()
 
struct TranslationCommand {
  var from:String
  var to:String
  var text:String
}
 
var translationCommand:TranslationCommand = TranslationCommand(from:"en",
                                                               to:"es",
                                                               text:"")

import PackageDescription
 
let package = Package(
  name:  "translator",
  dependencies: [
    .Package(url:  "https://github.com/iachievedit/CJSONC", majorVersion: 1),
    .Package(url:  "https://github.com/PureSwift/CcURL", majorVersion: 1)
  ]
)