feat(symbols): Added symbol source

[nhat-vo]

A simple source to view LSP symbols in the current file.
Features:

• UI:
  • Display all symbols in the current file with symbol kinds
  • Symbols nesting
  • Configurable kinds' name and icon
  • Auto-refresh symbol list
• Commands
  • Jump to symbols, open symbol in split,... (open_split and friends)
  • Rename symbols (rename)
  • Preview symbol (preview and friends)
  • Hover docs
  • Call hierarchy
• LSP
  • LSP Support
  • LSP server selection (blacklist, use first, use all, etc.)
• CoC Support

Feel free to let me know if you have any comments on what additional features should be desired.

[nhat-vo]

The document_symbol source is good for now (it is not enabled by default as there might still be bugs). I will implement the hover_docs, call_hierarchy, and CoC Support in a future PR.

[cseickel]

First off, it's awesome that you are undertaking this, I can't wait to start using it!

I do think there is more work to do before it's ready for merging though. I haven't dug deep into the code but I have some suggestions at the surface level here.

I also noticed that it does not automatically update when I change files, which is something that I think would be expected by anyone using it.

[nhat-vo]

I'm very glad to hear that you like this! Regarding the automatic update, I will have a look at why it is not auto-updating. Previously, I used the User LspRequest event, which updates the tree automatically on change and when the current buffer is changed (and every time any LSP Request is made), but this means that navigate is called twice every time the source is opened, so I switched to using these events instead.

[nhat-vo]

@cseickel I can't seem to reproduce your issue with automatic file changes. For me, whenever I change the file, the document_symbols source is updated accordingly. Could you provide the steps to reproduce this?

Edit: Actually, undoing doesn't refresh this, and it seems that there is no other way to hook onto undoing, so I'm falling back to using the User LspRequest event. I have added loading to the source's state, which will help limit repeated calls.

[nhat-vo]

Actually, I ended up changing it to several separate events and using utils.debounce. Seems to refresh at the right moment and the right amount now.

[cseickel]

Looks good.

[cseickel]

@nhat-vo I think this looks good as an initial release and I'll merge it now. The two things I would add to make it complete are:

• Follow cursor: just like "follow current file", I would expect the symbol tree to always have the symbol I'm currently on be selected.
• fuzzy search: I would implement the search commands to be able to search/filter the list of document symbols.

[nhat-vo]

@cseickel Great! I'm very glad to see this merged! I'll create an issue to track the features of this source.