int3 / metajs

Visualize your Javascript with a CPS metacircular interpreter.

metajs

A CPS Javascript metacircular interpreter that visualizes script execution.

Written in IcedCoffeeScript. Uses Esprima for the parser and CodeMirror for the front-end.

Setup

npm install
npm install -g [email protected] [email protected]

Usage

To start the REPL:

./repl.coffee

To execute a file:

./repl.coffee [filename]

To run in the browser:

make browser
cd browser
python -m SimpleHTTPServer

Then point your browser to http://localhost:8000/.

Testing

make test

Contributors

• omphalos

metajs's Issues

Exception 'metajs.js:155 Uncaught TypeError: Cannot set property 'value' of undefined'

Following code:

function* foo(){
  var index = 0;
  while(index <= 2) // при достижении 2, done в yield станет true, а value undefined;
    yield index++;
}

var iterator = foo();
console.log(iterator.next()); // { value:0, done:false }
console.log(iterator.next()); // { value:1, done:false }
console.log(iterator.next()); // { value:2, done:false }
console.log(iterator.next()); // { value:undefined, done:true }

Led to exception 'metajs.js:155 Uncaught TypeError: Cannot set property 'value' of undefined' on row
'console.log(iterator.next()); // { value:1, done:false }'

Browser: Chrome 53.0.2785.116 (64-bit)

Make fails

$ make browser
iced -c -I browserify lib/interpreter.coffee
lib/interpreter.coffee:243:11: error: await'ed statements can't act as expressions
          for arg in node.arguments
          ^^^^^^^^^^^^^^^^^^^^^^^^^
make: *** [lib/interpreter.js] Error 1

https://github.com/int3/metajs/blob/master/lib/interpreter.coffee#L243-L245

Value of function with no return statement should be undefined

The following test fails:

console.log((function() { 1; })());

The following Code gets stuck

Code sample:
function Human() { this.H1 = 87;}
var Obj = {
Name:"Palash"
}
Human.apply( Obj );
//------------------------------------------
Error: Function name: CPSFunction.prototype.apply in (bundle.js) errCont is undefined.
//------------------------------------------

License

Great work! However, I looked and couldn't find a license; under what terms may people use this source code?

Hoisting fails

The following test throws an exception, but shouldn't:
x(); function x() { console.log(1); }

Ajax example

Hey!

Nice project. I wonder why this code does not work:

$.ajax({
  url:'http://int3.github.io/metajs/',
  success: function(data){
    console.log(data);
  }});

Any clues?
Thanks!
Bartek

Switch back to plain Coffeescript.

I've decided that I don't like IcedCoffeeScript all that much :( See reasons here: plasma-umass/doppio#158 (comment)

Bring back JSException

Hi! Is there any objection to bringing back JSException? I think it provides a lot of useful information about exceptions when they occur. I can reintroduce if you are okay with the idea.