##JavaScript to PHP
This tool transforms JavaScript to PHP. Just for fun. Kind of like php.js but the opposite.
This is a proof-of-concept started at a hackathon recently and as far as I can tell, hasn't been done before, so why not?. There's some interesting properties of the two languages that make this a really interesting challenge: lexical scope, prototypal inheritance, duality of + operator in JS, PHP's implicit variable declaration, differences in Regular Expression implementations, etc. A lot of this had to be implemented in the form of runtime helpers and type checking, but it turns out it's totally doable.
There are heaps of "compile to JS" languages out there (Coffee, TypeScript, Dart), but next to nothing for PHP. PHP is ubiquitous in bulk hosting (upwards of 80% of the market), PHP runs on Google App Engine, AppFog, Rackspace Cloud Sites, etc. So if you need to host on PHP but don't like writing PHP, well you're hosed. ...unless you could write in JS and deploy in PHP.
Well, maybe so. But if you were going to write in one language and compile to PHP, why not JS (or a subset of it). There already exists parsers, static analysis tools, lint tools, refactoring utilities. And you have to know JS anyway because it's in the browser. OK, I'm not suggesting you write production code using this, but who knows, maybe it will mature into something you can take to production in some use-cases. I can imagine at some point in the future someone creating a cool thing in JS and via this tool being able to put it up on CodeCanyon in PHP. The same application might then be run on Node using Fibers and the JVM via Nahsorn or DynJS.
Sure, you pay a performance penalty at runtime, but seriously, have you run mainstream PHP apps before? It's not exactly like the performance bar is too high (I think a default install of WP performs 27 SQL queries to load the homepage once). Your app is likely not CPU bound and if it is, then you should be running Node + worker processes or some other awesome solution.
Anyway, I'm focusing on correctness, not performance, and this is very alpha stuff, so don't expect too much.
The core language functionality is mostly implemented and has some tests (Object, Array, Math lib, String methods, etc) but there is no interface to the outside world besides console.log(). There's no file-system, HTTP or Database module and there's no formal way to call into PHP from JS at this point.
Feel free to contribute if this interests you.
git clone [email protected]:sstur/js2php.git
cd js2php
npm install
echo "var a = 1; console.log(a + 1)" > example.js
node js2php --runtime > runtime.php
node js2php example.js > example.php
php -f example.php
We're using the awesome esprima JavaScript parser with rocambole to walk the AST and escope to figure out what is lexically scoped and hoist function declarations and so on. After several passes of AST manipulation transformer/codegen.js generates the PHP code from walking the tree.
Various constructs get wrapped in helper functions, for instance, property access, method calls, &&, || and + operators. The runtime helpers for this mostly live in php/helpers and there are a bunch of classes in php/classes for Array, RegExp and such. All this PHP gets packaged into runtime.php which is required from your output file.
Have a play with the online demo, but the output code looks something like this:
<?php
require_once("runtime.php");
$HelloWorld = new Func("HelloWorld", function($this_, $arguments, $greeting) {
set($this_, "greeting", $greeting);
});
set(get($HelloWorld, "prototype"), "go", new Func(function($this_, $arguments, $subject) use (&$console) {
call_method($console, "log", get($this_, "greeting"), $subject);
}));
call_method(x_new($HelloWorld, "Hi"), "go", "world");It's not particularly elegant, but it's human-readable and has all the basics we need to implement standards-compliant JS in PHP.