Support string/numeric/boolean literal types

[jfirebaugh]

JSDoc supports, e.g.:

/**
 * @typedef {Object} Comment
 * @property {('public'|'protected'|'private')} access
 */

jsdoc -X output looks like:

...
        "properties": [
            {
                "type": {
                    "names": [
                        "'public'",
                        "'protected'",
                        "'private'"
                    ]
                },
                "name": "access"
            }
        ],
...

This is useful to support enumerated types. See, for instance, jsdoc/jsdoc#629, jsdoc/jsdoc#1065, and documentationjs/documentation#373.

[nzakas]

And what happens when you try to parse it with Doctrine? I'm assuming you're saying something isn't working, but a full bug report with what you did, you happened, what you expected, etc. would be very helpful.

[jfirebaugh]

Ah, yeah, sorry. The comment fails to parse with doctrine. If you have the recoverable option set, you can get back an error message, which is "unexpected token".

[nzakas]

I don't have time to look into this at the moment, but I'd be happy to review a pull request.

[mister-walter]

Created #172 to add support for numeric and string literals. Boolean literal support is slightly more complicated, but I can work on that if there is a desire for it.