feat: Option for grouping empty directories

[sindrets]

Fixes #191.
This adds an option g:nvim_tree_group_empty (disabled by default) that compacts dirs that only contain 1 dir / symlink dir, into one node in the file tree.

[kyazdani42]

thanks a lot ! The overall algorithm is perfect and the feature works perfectly.
I must note that toggling this behavior would be useful if you want to add files in between grouped folders :)
Merging this anyway :)

[gegoune]

Using lua to configure this, is setting this option to true suppose to work?

vim.g.nvim_tree_group_empty = true

does not work, while

vim.g.nvim_tree_group_empty = 1

does.

Some other options I have set to true do work as expected.

[kyazdani42]

that's strange, if you find issues refering to the documentation please leave an issue.
I also have to work on that setup flow, but i'd like to finish the buffer thing first. It will make the plugin configuration more lua like.

[Lux3mb0urg]

Is there a callback function to toggle this feature?
Changing value of vim.g.nvim_tree_group_empty does not work.

[kyazdani42]

it does work for me though, just assign it to 1 (vim.g.nvim_tree_group_empty must be set in lua not in vimscript)

[sindrets]

@cloggier I implemented the option the same way all the other boolean options are currently implemented. The reason why only some options work when you set them to the lua value true is that comparing vim booleans and lua booleans is strange.

1 == true is a false lua statement. However, if 1 then ... end is a true lua statement. Which is why it will work sometimes to set vim variables to the lua value true. And to make things even more confusing true == vim.v["true"] is a true lua statement.

But when using vim variables in lua, you should treat them like vim variables. That means you should use 1 for true and 0 for false until proper lua configuration is implemented.

@Lux3mb0urg no, I did not implement a toggle function.

[gegoune]

@sindrets tusen takk for detailed response and amazing PR!

[kyazdani42]

indeed until i don't make the setup refactoring, this option thing will keep being clunky.