This is an open source Swift3 to JavaScript/TypeScript and Java transpiler. It's written in Java using antlr4 parser generator.
Visit http://typeswift.com for live transpilation preview.
It has support for Swift:
To get a better sense of supported features, have a look inside the test directory, which contains Swift code snippets that demonstrate supported features in greater detail.
The transpiler currently lacks support for:
Also, check out my reverse project (TypeScript to Swift transpiler): https://github.com/marcelganczak/ts-swift-transpiler
Arrays
let array = ["Swift", "is", "ace"]
print(array.count)
print(array[0].characters.count)const array:Array<string> = [ "Swift" , "is" , "ace" ] ;
console.log(array.length);
console.log(array[0 ].length);List<String> array = new ArrayList<String>(Arrays.asList("Swift", "is", "ace"));
System.out.println(array.size());
System.out.println(array.get(0 ).length());Dictionaries
var dictionary: [String:Int] = ["key" : "val"]
print(dictionary.count)
dictionary["key"] = nillet dictionary:Object = {"key" :"val" };
console.log(_.size(dictionary));
delete dictionary["key" ];Map<String, Integer> dictionary = new InitializableHashMap<String, Integer>(new Pair<String, Integer>("key" , "val" ));
System.out.println(dictionary.size());
dictionary.remove("key" );Tuples
let tuple: (a:String, count:Int) = ("str", 3)
print(tuple.a)
print(tuple.count)const tuple:Object = {'a':"str" ,'count':3 };
console.log(tuple.a);
console.log(tuple.count);Map<String, ?> tuple = new InitializableHashMap<String, Object>(new Pair<String, String>("a", "str" ),new Pair<String, Integer>("count", 3 ));
System.out.println(((String)tuple.get("a")));
System.out.println(((Integer)tuple.get("count")));For in range
for number in 0...10 {
guard number < 3 else {
break
}
print(number)
}for(let number = 0 ; number <= 10 ; number++) {
if(!(number < 3 )) {
break;
}
console.log(number);
}for(int number = 0 ; number <= 10 ; number++) {
if(!(number < 3 )) {
break ;
}
System.out.println(number);
}For in collection
let numberOfLegs = ["ant": 6, "cat": 4, "spider": 8]
for (animalName, legCount) in numberOfLegs {
print(animalName)
print(legCount)
}const numberOfLegs:Object = {"ant" :6 , "cat" :4 , "spider" :8 };
for(let animalName in numberOfLegs) {
let legCount = (numberOfLegs)[animalName];
console.log(animalName);
console.log(legCount);
}Map<String, Integer> numberOfLegs = new InitializableHashMap<String, Integer>(new Pair<String, Integer>("ant" , 6 ), new Pair<String, Integer>("cat" , 4 ), new Pair<String, Integer>("spider" , 8 ));
for(Map.Entry<String, Integer> $ : (numberOfLegs).entrySet()) {
String animalName = $.getKey();
Integer legCount = $.getValue();
System.out.println(animalName);
System.out.println(legCount);
}If let
let numberOfLegs = ["ant": 6, "cat": 4, "spider": 8]
if let catLegs = numberOfLegs["cat"] {
print(catLegs);
}const numberOfLegs:Object = {"ant" :6 , "cat" :4 , "spider" :8 };
if(numberOfLegs["cat" ] != null) {
const catLegs:number = numberOfLegs["cat" ];
console.log(catLegs);
}Map<String, Integer> numberOfLegs = new InitializableHashMap<String, Integer>(new Pair<String, Integer>("ant" , 6 ), new Pair<String, Integer>("cat" , 4 ), new Pair<String, Integer>("spider" , 8 ));
if(numberOfLegs.get("cat" ) != null) {
Integer catLegs = numberOfLegs.get("cat" );
System.out.println(catLegs);
}var dictionary = ["key" : "val"]
print(dictionary["non-existent"]?.characters.count)
print(dictionary["non-existent"] ?? "key doesn't exist!")
dictionary?["key2"] = "val2"let dictionary:Object = {"key" :"val" };
console.log((dictionary["non-existent" ]!= null ? dictionary["non-existent" ].length : null ));
console.log((dictionary["non-existent" ] != null ? dictionary["non-existent" ] : "key doesn't exist!" ));
if(dictionary != null) { dictionary["key2" ] = "val2" ; };Map<String, String> dictionary = new InitializableHashMap<String, String>(new Pair<String, String>("key" , "val" ));
System.out.println((dictionary.get("non-existent" ) != null ? dictionary.get("non-existent" ).length() : null ));
System.out.println((dictionary.get("non-existent" ) != null ? dictionary.get("non-existent" ) : "key doesn't exist!" ));
if(dictionary != null) { dictionary.put("key2" , "val2" ); };Overloading
func justPrint(_ printed: String) {
print("String: \(printed)")
}
func justPrint(_ printed: Int) {
print("Int: \(printed)")
}
func justPrint(_ printed: Double) {
print("Double: \(printed)")
}
justPrint("message")
justPrint(1)
justPrint(2.1)function justPrint$_String(printed : string):void{
console.log("String: " + (printed) + "" );
}
function justPrint$_Int(printed : number):void{
console.log("Int: " + (printed) + "" );
}
function justPrint$_Double(printed : number):void{
console.log("Double: " + (printed) + "" );
}
justPrint$_String("message" );
justPrint$_Int(1 );
justPrint$_Double(2.1 );No support in Java yet.Non-primitive return types
func returnOptionalTuple(shouldReturn: Bool) -> (Int,String)? {
return shouldReturn ? (0, "val") : nil
}
print(returnOptionalTuple(shouldReturn: false)?.0)
print((returnOptionalTuple(shouldReturn: true)?.0)!)function returnTuple():Object{
return {'0':0 ,'1':"val" };
}
console.log(returnTuple()[0 ]);No support in Java yet.In-Out parameters
func incr(_ a: inout Int) {
a = a + 1
}
var a = 0
incr(&a)
print(a)function incr$_Int(a : {get: () => number, set: (val: number) => void}):void{
a.set( a.get() + 1 );
}
let a:number = 0 ;
incr$_Int({get: () => a, set: $val => a = $val});
console.log(a);No support in Java yet.Operator methods
var numbers = [5, 2, 3, 1, 4]
numbers.sort(by: <)let numbers:Array<number> = [ 5 , 2 , 3 , 1 , 4 ] ;
numbers.sortBool((a, b) => a < b);No support in Java yet.Shorthand argument names
var numbers = [5, 2, 3, 1, 4]
let sum = numbers.filter {
$0 % 2 == 1 //select all the odd numbers
}.map {
$0 * $0 // square them
}.reduce(0) {
$0 + $1 // get their sum
}let numbers:Array<number> = [ 5 , 2 , 3 , 1 , 4 ] ;
const sum:number = numbers.filter(
() => arguments[0] % 2 == 1
).map(
() => arguments[0] * arguments[0]
).reduce(
() => arguments[0] + arguments[1]
, 0);No support in Java yet.Getter/setter Properties
struct Square {
var a = 1.0
var perimeter: Double {
get {
return a * 4
}
set(newPerimeter) {
a = newPerimeter / 4
}
}
}
var square = Square()
square.perimeter = 16
print(square.perimeter)class Square {
a:number = 1.0 ;
perimeter$get(): number {
return this.a * 4 ;
}
perimeter$set(newPerimeter:number) {
this.a = newPerimeter / 4 ;
} ;
} ;
let square:Square = new Square();
square.perimeter$set( 16 );
console.log(square.perimeter$get());No support in Java yet.Swift is the official new language behind iOS apps. On top of that, its ease of use coupled with great performance make it a strong contender for a future back-end language (a compiler has already been released for linux).
Wouldn't it be great to be able to share business logic across the whole mobile environment? No need to maintain four different code bases (back-end, iOS, Android and browser)!
This transpiler is more robust than any solution I could find online. Using antlr4 is a huge advantage over hand coding lexers & parsers -- it's more reliable and more maintainable.
The project is undergoing rapid development and ideally it would have complete Swift support. I welcome any contributions. Feel free to drop me a line at [email protected]
You will need Java to run the transpiler.
It will grab the contents of example.swift in the root folder and print the transpiled TypeScript into console.
To find out how to then transpile TypeScript further to JavaScript, check https://www.typescriptlang.org/
In order to run the tests, you need xcode and node as well as typescript and mocha npm packages installed globally.
cd test
mochaThe test will iterate through all swift files within the test directory, run both the original Swift code and the transpiled TypeScript/Java code and compare the console output.
MIT