Catharsis

A JavaScript parser for Google Closure Compiler and JSDoc 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 convert parse results back into type expressions. In addition, it can parse JSDoc-style type expressions.

Example

var catharsis = require('catharsis');

var type;
var jsdocType;
var parsedType;
var parsedJsdocType;

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

// JSDoc-style type expressions enabled
try {
    jsdocType = 'string[]';  // Closure Compiler expects Array.<string>
    parsedJsdocType = catharsis.parse(jsdocType, {jsdoc: true});
}
catch (e) {
    console.error('unable to parse %s: %s', jsdocType, e);
}

console.log(catharsis.stringify(parsedType));       // !Object
console.log(catharsis.stringify(parsedJsdocType));  // string[]
console.log(catharsis.stringify(parsedJsdocType,    // Array.<string>
    {restringify: true}));

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

Methods

parse(typeExpression, options)

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

When called without options, Catharsis attempts to parse type expressions in the same way as Closure Compiler. When the jsdoc option is enabled, Catharsis can also parse several kinds of type expressions that are permitted in JSDoc:

• The string function is treated as a function type with no parameters.
• In a function type with repeatable parameters, the names of repeatable parameters are not required to be enclosed in square brackets (for example, function(...foo) is allowed).
• The period may be omitted from type applications. For example, Array.<string> and Array<string> will be parsed in the same way.
• You may append [] to a name expression (for example, string[]) to interpret it as a type application with the expression Array (for example, Array.<string>).
• Name expressions may contain the characters #, ~, :, and /.
• Name expressions may contain a suffix that is similar to a function signature (for example, MyClass(foo, bar)).
• Name expressions may contain a reserved word.
• Record types may use types other than name expressions for keys.

Parameters

• type: A string containing a Closure Compiler type expression.
• options: Options for parsing the type expression.
  • options.jsdoc: Specifies whether to enable parsing of JSDoc-style type expressions. Defaults to false.
  • options.useCache: Specifies whether to use the cache of parsed types. Defaults to true.

Returns

An object containing the parse results. See the test/specs/ directory for examples of the parse results for different type expressions.

The object also includes two non-enumerable properties:

• jsdoc: A boolean indicating whether the type expression was parsed with JSDoc support enabled.
• typeExpression: A string containing the type expression that was parsed.

stringify(parsedType, options)

Stringify 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.
• options: Options for stringifying the parse results.
  • options.cssClass: A CSS class to add to HTML links. Used only if options.links is provided. By default, no CSS class is added.
  • options.htmlSafe: Specifies whether to return an HTML-safe string that replaces left angle brackets (<) with the corresponding entity (<). Note: Characters in name expressions are not escaped.
  • options.links: An object whose keys are name expressions and whose values are URIs. If a name expression matches a key in options.links, the name expression will be wrapped in an HTML <a> tag that links to the URI. If options.cssClass is specified, the <a> tag will include a class attribute. Note: When using this option, parsed types are always restringified, and the resulting string is not cached.
  • options.restringify: Forces Catharsis to restringify the parsed type. If this option is not specified, and the parsed type object includes a typeExpression property, Catharsis will return the typeExpression property without modification when possible. Defaults to false.
  • options.useCache: Specifies whether to use the cache of stringified parse results. Defaults to true.
  • options.validate: Specifies whether to validate the stringified parse results by attempting to parse them as a type expression. If the stringified results are not parsable by default, you must also provide the appropriate options to pass to the parse() method. 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

• 0.7.0 (October 2013):
  • Repeatable type expressions other than name expressions (for example, ...function()) are now parsed and stringified correctly.
  • Type expressions that are both repeatable and either nullable or non-nullable (for example, ...!number) are now parsed and stringified correctly.
  • Name expressions are now parsed correctly when they match a property name in an object instance (for example, constructor).
• 0.6.0 (September 2013): Added support for the type expression function[] when JSDoc-style type expressions are enabled.
• 0.5.6 (April 2013):
  • For consistency with Google Closure Library, parentheses are no longer required around type unions. (In previous versions, the parentheses could be omitted when JSDoc support was enabled.)
  • For consistency with Google Closure Library, you can now use postfix notation for the ? (nullable) and ! (non-nullable) modifiers. For example, ?string and string? are now treated as equivalent.
  • String literals and numeric literals are now allowed as property names within name expressions. For example, the name expression Foo."bar" is now parsed correctly.
• 0.5.5 (April 2013): Corrected a parsing issue with name expressions that end with a value enclosed in parentheses.
• 0.5.4 (April 2013):
  • Repeatable literals (for example, ...*) are now parsed correctly.
  • When JSDoc-style type expressions are enabled, a name expression can now contain a value enclosed in parentheses at the end of the name expression (for example, MyClass(2)).
• 0.5.3 (March 2013): The parse() method now correctly parses name expressions that contain hyphens.
• 0.5.2 (March 2013): The parse() method now correctly parses function types when JSDoc-style type expressions are enabled.
• 0.5.1 (March 2013): Newlines and extra spaces are now removed from type expressions before they are parsed.
• 0.5.0 (March 2013):
  • The parse() method's lenient option has been renamed to jsdoc. Note: This change is not backwards-compatible with previous versions.
  • The stringify() method now accepts cssClass and links options, which you can use to add HTML links to a type expression.
• 0.4.3 (March 2013):
  • The stringify() method no longer caches HTML-safe type expressions as if they were normal type expressions.
  • The stringify() method's options parameter may now include an options.restringify property, and the behavior of the options.useCache property has changed.
• 0.4.2 (March 2013):
  • When lenient parsing is enabled, name expressions can now contain the characters : and /.
  • When lenient parsing is enabled, a name expression followed by [] (for example, string[]) will be interpreted as a type application with the expression Array (for example, Array.<string>).
• 0.4.1 (March 2013):
  • The parse() and stringify() methods now honor all of the specified options.
  • When lenient parsing is enabled, name expressions can now contain a reserved word.
• 0.4.0 (March 2013):
  • Catharsis now supports a lenient parsing option that can parse several kinds of malformed type expressions. See the documentation for details.
  • The objects containing parse results are now frozen.
  • The objects containing parse results now have two non-enumerable properties:
    • lenient: A boolean indicating whether the type expression was parsed in lenient mode.
    • typeExpression: A string containing the original type expression.
  • The stringify() method now honors the useCache option. If a parsed type includes a typeExpression property, and useCache is not set to false, the stringified type will be identical to the original type expression.
• 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.