##JavaScript to PHP
This tool transforms JavaScript to PHP. Just for fun.
This is a proof-of-concept started at a hackathon recently, just for fun. There are various aspects 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, etc. A lot of this had to be implemented in runtime helpers with type checking, but it turns out JavaScript and PHP are similar enough to do this as a source transformation without actually building an interpreter.
There are dozens of "compile to JS" languages available (Coffee, TypeScript, Dart), but not many good choices in the PHP space**. PHP is ubiquitous in bulk hosting, it runs on almost every web server around. PHP applications are generally easy to host and maintain. So if you need to host on PHP but don't like writing PHP, well tough. ...unless you could write in JS and deploy to PHP!
Maybe so. But if you wanted a compile-to-PHP language, JavaScript is a fairly solid choice. There's heaps of tooling, libraries, community, etc. Plus web developers should know JavaScript anyway because it's the language of the browser. We're not at a place where you can really deploy this stuff to production, but that could become feasible at some point. I can imagine building a simple web app in JS and then compiling it to PHP to run on a LAMP stack and then run the same application on Node using Fibers or maybe even on the JVM via Nahsorn or DynJS (stay tuned for a PoC).
Another use case might be allowing some user-generated scripting (think plugins). Your application could compile user-generated JS safely to PHP to be run server-side. None of the usual PHP functions are exposed and there is no disk/network access or eval. You can expose a carefully defined set of functions to JS land.
Sure, you'll take a performance hit at runtime, but let's face it, mainstream PHP apps haven't exactly set the performance bar too high (I think a default WP install runs 27 SQL queries to render a single page). Your app is likely not CPU bound anyway (and if it is, you should be running Node + worker processes or some other awesome solution).
At this point I'm focusing on correctness, not performance, and this is very alpha stuff, but so far it seems the performance penalty is not prohibitively expensive.
The core language constructs, classes and methods are mostly implemented and we have decent test coverage. I'm working on an opt-in module system to interface with request/response and file-system. Database access, HTTP client, crypto and other modules to follow. Specific modules can be specified at compile time; by default js2php will only allow access to the outside world via console.log() and process.exit() so the generated PHP is completely safe.
Feel free to contribute if this interests you.
Install from GitHub:
git clone git@github.com:sstur/js2php.git
cd js2php
npm install
Install from npm:
npm install -g jstophp
When you install from npm using the -g flag, you can run it from any directory by simply calling js2php rather than calling node path/to/js2php. The rest of the examples in this readme will call it this way.
Compile and run a simple example:
echo 'var x = "world"; console.log("hi " + x)' | js2php --quiet | php
or, a more verbose example:
echo "var a = 1; console.log(a + 1)" > example.js
js2php example.js > example.php
php example.php
We're using the awesome esprima JavaScript parser with rocambole to walk the AST and escope to figure out variable scope, hoist function declarations and so on. After AST manipulation tools/codegen.js generates the PHP code by walking the tree.
Various constructs get wrapped in helper functions, for instance, property access, method calls and + operator. The runtime helpers can be found in php/helpers and there are a bunch of classes in php/classes for Array, RegExp and such. All this PHP gets packaged into your output file, or you can save it to a standalone runtime and reference that from your output file like so:
js2php --runtime-only > runtime.php
js2php --runtime runtime.php example.js > example.php
You can also specify the output file using -o or --out and you can compile multiple input files into one output file like so:
js2php -o example.php file1.js file2.js
Have a play with the online demo. The generated code will look something like this:
<?php
$HelloWorld = new Func("HelloWorld", function($greeting = null) {
$this_ = Func::getContext();
set($this_, "greeting", $greeting);
});
set(get($HelloWorld, "prototype"), "greet", new Func(function($subject = null) use (&$console) {
$this_ = Func::getContext();
call_method($console, "log", get($this_, "greeting"), $subject);
}));
call_method(_new($HelloWorld, "Hi"), "greet", "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.
There are a handful of other projects worth noting. Haxe is probably the most popular and is a solid statically-typed language which compiles to PHP (among others). gutscript and Mammouth are both syntactically similar to CoffeeScript, Pharen is a Lisp implementation and Pratphall uses TypeScript syntax. There's also another project with the same name as this which is similar at the parsing level, but somewhat different in execution. It accepts JS syntax but otherwise behaves like PHP.
Most of these projects are either incomplete or abandoned which is a shame. I love the idea of writing PHP in a friendlier syntax, especially if the source-transform can iron out some of the core inconsistencies in to PHP. It would be great to see more usable choices in this space!
Run npm test. Requires PHP 5.3+ or HHVM.
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