Skip to content
Basic Java to Swift syntax converter
Java ANTLR Other
Branch: master
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
.idea
src
test
.gitignore
LICENSE.txt
README.md
antlr.iml initial checkin Apr 9, 2015
gui.sh
j2swift.sh

README.md

j2swift

@author Pat Niemeyer (pat@pat.net)

This is a very basic Java 8 to Swift 1.2 syntax converter. It handles things like flipping type arguments around and rewriting method signatures and constructors. This is by no means a complete Java to Swift translator as it does not make API updates other than in trivial cases.

The converter preserves whitespace and should leave the input untouched in places that it doesn't update, so it is somewhat useful even when it leaves work to be done. For simplistic Java code (e.g. business logic) I'd say this gets you 80% of the way there.

See test/Test.java and test/Test.swift for an idea of what is currently handled.

A few things it does

  • Rewrites static and instance field declarations
  • Rewrites method and init argument lists
  • Rewrites constructors and constructor invocations, including attempting to note convenience intializers
  • Rewrites simple array types
  • Rewrites 'this' references as 'self'
  • Rewrites for, enhanced for, and while loops
  • Maps float, int, long and boolean types
  • Maps null to nil
  • Comments out throws statements and replaces them with a placeholder method invocation throwException()
  • Maps interface to protocol
  • Maps System.out.println() to println()

A few things it could do in the future

  • Final vars should become "let" vars.
  • Method and fields with the same name should be disambiguated.
  • Static method invocations should be qualified.

Building

It's just a handful of Java files in src. The only requirement is the ANTLR runtime:

http://www.antlr.org/download/antlr-4.5-complete.jar or http://www.antlr.org/download/antlr-runtime-4.5.jar

The ANTLR grammar for Java is provided for reference but you do not have to build the parser to make changes. All updates really happen in the J2SwiftListener class.

J2Swift takes a filename or stding as input and outputs to stdout.

You can’t perform that action at this time.