Refactor treesitter filetype detection

[zdm]

This patch allows to flexibly define snippets for injected languages.
Now treesitter filetype detector returns two filetypes:

1. filetype for code under the cutsor;
2. combined filetype for code under the cursor + parent code block (for injected language);

For example, for lua injected into vim script it will retirn:

{
    filetype = "lua",
    injected_filetype = "vim/lua",
}

This will allow users to configure snippets more flexibly. For example, if I want to add some snippets for lua code, injected into vim, for example vim.print( $1 ), I will need to setup filetypes mapping like this:

vim.g.vsnip_filetypes = {
    [ "vim/lua" ] = { "lua", "vim/lua" },
}

So for regular lua script lua.json snippets will be used, and for injected vim/lua - lua.json and vim/lua.json.

[zdm]

I have no idea, why tests are failed.
There are no any helpful messages in the log.
For me it works under linux and winfows.
Could you take a look please?

[hrsh7th]

Thank you.

Is there any precedent in the vim/neovim ecosystem for calling an embedded file type something like vim/lua?

If it's a custom extension I would be hesitant to merge the PR.

[zdm]

No conflicts with vim/nvim.
This format ("vue/htnl", etc...) is used internally only and does not passed to the editor.
It used only in the lua code to find appropriate filetypes mapping (if they were defined by the user).

[zdm]

I changed filetype separator to ".", this is more vim-like. This doesn't affect anything, just for consistency.

[zdm]

@hrsh7th
Hi, will you accept it? Tell me please if you have any questions.

[zdm]

Hi, man.
So, what is your decision?
Please, reject it, if you don't want this changes.

[hrsh7th]

What I'm wondering is that this function is so useful and versatile that a standard mechanism will eventually be implemented in the neovim core.

In other words, if we choose ft/ft or ft.ft here and the official version chooses ft#ft, it will lose consistency.

Apart from that, I think ft/ft is better.

For now, let's merge with ft/ft.

[zdm]

So, should I revert separator back from "." to "/" and you will merge?

[hrsh7th]

yes :)

[zdm]

Filetype separator reverted to "/".

[hrsh7th]

thank you

[zdm]

Thank you!