Astral Pass

Pass system for Astral.

Pass Types

There are two kinds of passes: info, and transform.

$3

Info passes operate on a copy of the AST,
but are allowed to modify the info object passed into the function as a parameter.

``javascript
myPass.
info(function (chunk, info) {
info.foo = 'bar'; // persists

chunk.foo = 'bar'; // does not persist
});
`

$3


Transforms, on the other hand, allow you to modify the structure of the part of the AST that the pass matches,
but prevents you from making changes to the info parameter.

`javascript
myPass.
info(function (chunk, info) {
info.foo = 'bar'; // does not persist

chunk.foo = 'bar'; // persists
});
`

Example

Below is a simple example.

`javascript
var myPass = require('astral-pass')();

myPass.name = 'myPass';
myPass.prereqs = [ / other pass names here / ];

myPass.
when({
// ... AST chunk
}).
when(function (chunk, info) {
// return true or false
}).
transform(function (chunk, info) {

});
`

More Complicated Passes

You can introduce more complicated behavior by composing passes.
This is done by modifying a pass's prereques property.

`javascript
var astralPass = require('astral-pass');

// p1 needs some info to do its transformations

var p1 = astralPass();
p1.name = 'myPass';
p1.prereqs = [ 'p2' ];

p1.
when( ... ).
transform( ... );

// p2 gathers the info for p1

var p2 = astralPass();
p2.name = 'myPass';

p2.
when( ... ).
info( ... );

`

I recommend namespacing passes with :`.

License

MIT