feat: add highlight open files

[nhat-vo]

Added highlight open file feature as described in #743. I'm not sure if there is any better way to cache this so that we do not have to loop over all buffers every time. Do you think adding to state is a good idea?

[miversen33]

I love this idea :) That said, honestly I feel like (IMO) looping over the buffers each time isn't that big of a deal, especially if we only perform said change on a Buffer Change event (such as BufDelete/BufAdd event). At the end of the day, lua is fast and a loop operation (even over several thousand items) per event loop iteration is still effectively instant. Thats not to say that thinking about "caching" or reducing the work is a bad thing, just that its probably not going to have a massive performance impact. Even less of an impact if we tie it only to event changes.

One thing I would be curious about, this will highlight all open files with the same highlight right? Is there a way we can highlight the currently focused file different if its one of the files visible in Neotree?

[nhat-vo]

@miversen33 Thanks for your insights! I also think that caching might not result in a noticeable impact in performance, and adding the buffer list into state seems rather complicated so I'm not sure if I should implement this.

Regarding the focused file, are you talking about the follow_current_file option?

[miversen33]

Regarding the focused file, are you talking about the follow_current_file option?

Yes. Does the proposed highlighting overrule that option? I am at work so I cannot test this right now lol. My main concern is that while having all open files highlighted makes a ton of sense, I wouldn't want this to supersede other options (such as follow_current_file)

[nhat-vo]

@miversen33 it doesn't seem so. The focused file will both has the NeoTreeFileNameOpened and the highlight from follow_current_file like this:

[miversen33]

Reading code is hard lol. It looks like you are already using the event system for triggering the highlight logic. As long as the current focused file is distinct from the other open files, LGTM :)

[nhat-vo]

@cseickel I have refactored the modified_buffers list to opened_buffers and added the configs as you suggested. I find opened is less ambiguous than open in describing the status, as open also refers to the action.
To make the change more uniform, I also renamed the library function in buffers.items to opened instead of open, in case you don't mind 😅.

[cseickel]

This looks great, there's just one more thing. Technically, the utils module is part of the public api and changing the signature or return type of a function in the utils module that does not start with a _ is a breaking change that is not allowed within a major version: https://github.com/nvim-neo-tree/neo-tree.nvim#what-is-a-breaking-change

To work around that, can you just add a function that mimics the old get_modified_buffers()? It can be marked as deprecated using a comment:

--- DEPRECATED: This will be removed in v3
---Gets a lookup of all open buffers keyed by path with the modifed flag as the value
---@return table
M.get_modified_buffers = function()

Internally, it should just call the new function and convert it to the simple table of booleans that was returned before.

[nhat-vo]

@cseickel Done!

[cseickel]

Looks good, thanks!