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A JavaScript parser for Google Closure Compiler and JSDoc type expressions.

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A JavaScript parser for Google Closure Compiler type expressions.

Catharsis is designed to be:

  • Accurate. Catharsis is based on a PEG.js grammar that can handle any valid type expression, no matter how complex. It uses a Mocha test suite to verify the parser's accuracy.
  • Fast. Parse results are cached, so the parser is invoked only when necessary.
  • Flexible. Catharsis provides both asynchronous and synchronous interfaces.


Asynchronous interface:

var catharsis = require('catharsis');

var type = '!Object';

catharsis.parse(type, function(error, parsed) {
    if (error) {
        console.error('unable to parse %s: %s', type, error);
    } else {
        console.log('%j', parsed);  // {"typeName":"Object","nullable":false}

Synchronous interface:

var catharsis = require('catharsis');

var type = '!Object';
var parsed;

try {
    parsed = catharsis.parseSync('!Object');  // {"typeName":"Object","nullable":false}
catch(e) {
    console.error('unable to parse %s: %s', type, e);

See the test/specs/ directory for more examples of Catharsis' parse results.


With npm:

npm install catharsis

Or without:

git clone git://

Roadmap and Known Issues

Take a look at the issue tracker to see what's in store for Catharsis.

Bug reports, feature requests, and pull requests are always welcome! If you're working on a large pull request, please contact me in advance so I can help things go smoothly.

Note: The parse tree's format should not be considered final until Catharsis reaches version 1.0. I'll do my best to provide release notes for any changes.


MIT license.

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