Catharsis

A JavaScript parser for Google Closure Compiler type expressions.

Catharsis is designed to be:

• Accurate. Catharsis is based on a PEG.js grammar that's designed to handle any valid type expression. 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 can also convert parse results back into type expressions.

Example

var catharsis = require('catharsis');

var type = '!Object';
var parsedType;
var expr;

try {
    parsedType = catharsis.parse('!Object');
    console.log('%j', parsedType);  // {"type":"NameExpression,"name":"Object","nullable":false}
}
catch(e) {
    console.error('unable to parse %s: %s', type, e);
}

expr = catharsis.stringify(parsedType);
console.log(expr);  // !Object

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

Methods

parse(type, opts)

Parse the Closure Compiler type type, and return the parse results. Throws an error if the type cannot be parsed.

Parameters

• type: A string containing a Closure Compiler type expression.
• opts: Options for parsing the type expression.
  • opts.useCache: Specifies whether to use the cache of parsed types. Defaults to true.

Returns

An object containing the parse results.

stringify(parsedType, opts)

Stringify the parsed Closure Compiler type expression parsedType, and return the type expression. If validation is enabled, throws an error if the stringified type expression cannot be parsed.

Parameters

• parsedType: An object containing a parsed Closure Compiler type expression.
• opts: Options for stringifying the parse results.
  • opts.useCache: Specifies whether to use the cache of stringified parse results. Defaults to true.
  • opts.validate: Specifies whether to validate the stringified parse results by attempting to parse them as a type expression. Defaults to false.

Returns

A string containing the type expression.

Installation

With npm:

npm install catharsis

Or without:

git clone git://github.com/hegemonic/catharsis.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.

Changelog

• 0.3.1 (March 2013): Type expressions that begin with a reserved word, such as integer, are now parsed correctly.
• 0.3.0 (March 2013):
  • The parse() and stringify() methods are now synchronous, and the parseSync() and stringifySync() methods have been removed. Note: This change is not backwards-compatible with previous versions.
  • The parse results now use a significantly different format from previous versions. The new format is more expressive and is similar, but not identical, to the format used by the doctrine parser. Note: This change is not backwards-compatible with previous versions.
  • Name expressions that contain a reserved word now include a reservedWord: true property.
  • Union types that are optional or nullable, or that can be passed a variable number of times, are now parsed and stringified correctly.
  • Optional function types and record types are now parsed and stringified correctly.
  • Function types now longer include new or this properties unless the properties are defined in the type expression. In addition, the new and this properties can now use any type expression.
  • In record types, the key for a field type can now use any type expression.
  • Standalone single-character literals, such as ALL (*), are now parsed and stringified correctly.
  • null and undefined literals with additional properties, such as repeatable, are now stringified correctly.
• 0.2.0 (November 2012):
  • Added stringify() and stringifySync() methods, which convert a parsed type to a type expression.
  • Simplified the parse results for function signatures. Note: This change is not backwards-compatible with previous versions.
  • Corrected minor errors in README.md.
• 0.1.1 (November 2012): Added opts argument to parse() and parseSync() methods. Note: The change to parse() is not backwards-compatible with previous versions.
• 0.1.0 (November 2012): Initial release.

License

MIT license.