Dynamic condition for formatters

[levouh]

Lets say that I have a few formatters setup for python files:

1. black, which will format the entire file
2. isort, which will act on the entire file
3. darker, which runs black but only applies edits to changed code

I want to be able to choose which "set" I use; sometimes I want to format the entire file, otherwise I want to format only the changed sections. Now I understand there is a conditional feature, but that deal with registration only, rather than each time I use a formatter.

Ideally, I'd be able to do something like map ,Ff to:

local function format_full()
  vim.g._null_format_diff = false
  vim.lsp.buf.formatting_sync()
end

and then map ,FF to:

local function format_diff()
  vim.g._null_format_diff = true
  vim.lsp.buf.formatting_sync()
end

such that I can later use a function with null-ls each time formatting is performed that does something like:

local n = require("null-ls")

local diff_fmt = function()
  return vim.g._null_format_diff
end

local full_fmt = function()
  return not vim.g._null_format_diff
end

n.config({
  sources = {
    n.builtins.formatting.isort.with({
      format_condition = diff_fmt,
    }),
    n.builtins.formatting.black.with({
      format_condition = full_fmt,
    }),
    custom.darker.with({
      format_condition = full_fmt,
    }),
  },
})

so that I can choose which set of formatters run. I'm happy to make a PR for something like this, but was curious if there was already a way to do it such that I don't waste my time. Curious on your thoughts @jose-elias-alvarez.

[levouh]

See #203