Doc on hover

[cdsmith]

When the user hovers the mouse over a standard library function, we should pop up a tool tip with basic type and documentation for that symbol.

[nixorn]

@cdsmith Hi from BountySource. I see this issue listed here https://www.bountysource.com/teams/codeworld/bounties, can I try to solve this?

[nixorn]

Is this issue still actual? Or any issues on bountysource?

[cdsmith]

Hi. Yes, this is still an actual issue, and you are welcome to work on it. I'm not aware of anyone else doing any work on this. Let me know if you have any trouble getting started.

You probably want this feature to use the same information as autocomplete, which is loaded here: https://github.com/google/codeworld/blob/master/web/js/codeworld_shared.js#L148 and the file being parsed is https://code.world/codeworld-base.txt . Right now, the doc comments are ignored when reading that file, and only names and type signatures are pulled out. I'd suggest starting with just that; a good first step would be to just display names and type signatures. To get the docs as well, you'd want to extend the parsing at https://github.com/google/codeworld/blob/master/web/js/codeworld_shared.js#L247 to read and build up a string that's applied to the next symbol.

[nixorn]

Thanks for explanation, I started.

[nixorn]

Looks CodeMirror tracks only editor cursor, not mouse coordinates, and have no event like "token.mouseover()" from jquery. I have not figure out with CodeMirror completely yet, and in search of best way.

Now I see 2 options:

1. use CodeMirror cursor events to determine when some text become highlighted variable, and create hidden tooltip element for this token like here. Css solution without extending CodeMirror defaults.
2. write CodeMirror custom addon, which will handle hover events. I'm not sure about this, need to deeper understanding of CodeMirror internals for that.

I did not start parsing yet, left it for dessert.

[cdsmith]

Hmm. It looks like CodeMIrror's cm.coordsChar lets you trade a mouse position for the line and column. The way I'd approach this is to listen for mouse events with CodeMirror's event registration, and then find the token using coordsChar.

I agree that packaging as a general CodeMirror addon would be great. I googled around for a bit, and found https://github.com/angelozerr/CodeMirror-XQuery/tree/master/codemirror-extension/addon/hover, which looks like a prior implementation. If that works out of the box, you could just add it to the third_party dir (with original copyright and all licensing), and then use symlink the files into the right places in web. If it's bitrotted (it's last modified in 2013), then you might need to build something yourself, but use that as a rough guide.

[cdsmith]

Oh, it looks like that addon may already exist in https://www.npmjs.com/package/codemirror-extension I don't know much about npm, so I'm not sure how to best incorporate that into the project.