[WIP] [Feedback] Inlining function call arguments

[ThaisRobba]

Hi there!

I wanted to be able to have inline anonymous function expressions, like so:

local ok, err = pcall(function()
    -- logic
end)

I've added a new configuration param inlineFunctionCalls, defaulting to true due to Lua's oficial documentation and common patterns (but can be persuaded to change it to default to false!) :-)

Examples:

-- input
local result = filter({1, 2, 3}, function(value) return 1 % 2 == 0 end)

-- output with inlineFunctionCalls: true
local result = filter({1, 2, 3}, function(value)
  return 1 % 2 == 0
end)

-- output with inlineFunctionCalls: false
local result = filter(
    {1, 2, 3},
    function(value)
        return 1 % 2 == 0
    end
)


-- desired (but not working yet) output with inlineFunctionCalls: true
local result = filter(
    {
        some_really_long_variable_name,
        some_even_larger_variable_name_I_mean_really_really_really_larger,
        this_feels_normal_in_comparison,
        tiny_1
    },
    my_func
)

-- desired (but not working yet) output with inlineFunctionCalls: true
local result = filter(
    {
        some_really_long_variable_name,
        some_even_larger_variable_name_I_mean_really_really_really_larger,
        this_feels_normal_in_comparison,
        tiny_1
    },
    function(value)
        return 1 % 2 == 0
    end
)

-- desired (but not working yet) output with inlineFunctionCalls: true
local result = test(
    {1, 2, 3},
    "helloooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo",
    "hi",
    true,
    nil,
    function(value)
        return 1 % 2 == 0
    end
)

-- Cannot be formatted yet
local result = test(
    {1, 2, 3}
    -- a comment
)

-- results in
local result = test({1, 2, 3}-- a comment)
-- which breaks tests and is clearly not correct

I'm marking this PR as [WIP] because it is not ready to be merged yet. I'd love to have @trixnz feedback on it :)

[trixnz]

Apologies for the radio silence @OttoRobba.

I like it! I'd be in favour of keeping it true by default.

With regards to the last example with the comment, I think the only option would be to keep the call broken onto multiple lines if there is a comment attached to any of the parameter nodes, unless there is a more idiomatic way of moving the comment.

[qaisjp]

I think something like this:

-- Cannot be formatted yet
local result = test(
    {1, 2, 3},
    -- true because true
    true
)

should be reformatted as:

 -- Cannot be formatted yet
 local result = test(
     {1, 2, 3},
+     
     -- true because true
     true
 )

I am not sure if there should be whitespace or not, but there should be a (configurable) newline IMO.

Thanks for this pull request @ThaisRobba, it's exactly what we're looking for here. And thank you @trixnz for this fantastic project.

I'll try and see if I can source some effort on this (either by myself or other developers), if you're not working on it @ThaisRobba.

[ThaisRobba]

@qaisjp I'm currently not working on this (no longer with the company I was working with), so feel free to tackle it and reuse any of my suggested changes :-)

I like the linebreak before the comment, good idea :-)

[trixnz]

I'd love to see an option for newlines, I think forcing it on users by default could be a little intrusive. We could begin with a command line option, although once #3 lands, I'd like to open a lot more of the format to customizations. Feel free to make issues for specific modifications you would like to see.

Comment support is in a really bad place right now, and I'm working (when time allows) on writing my own Lua parser to better expose the AST to allow the formatter to make better decisions.