How to display a colored file icon in the statusline?

Question

So I was setting up my status line and I wanted a function which gives the icon of current file type. But it has to be in string.

provider=function()
  str="{some icon}"
  return str
end

so far so good

But now I need colored ones because why not?

So I came across something like this

provider=function()
  local str = {}
  str.str = "{some_icon}"
  str.hl = {fg="#FFFFFF",}
  return str
end

but now str is not a string.

Is there a way to convert it to string while keeping its color? Or all together is there a better way to get a colored icon as string? And also without loading any plugins.

I use feline plugin to setup the statusline....below is an example for a component config

        vim_status = {
        provider = function()
            local s
            if require('lazy.status').has_updates() then
                s = require('lazy.status').updates()
            else
                s = ' '
            end
            s = string.format(' %s', s)
            return s
        end,
        hl =vi_mode_hl ,
                right_sep = {
            always_visible = true,
            str =  "",
            hl = vi_sep_hl,
        },
    },

I want to pass the icon to the provider field and this takes only string values

Answer 1

To control the color of the text of the status line you have to use highlighting groups and a special %#...#... syntax for the return value of your provider.

e.g.: To have Foo in green in your status line you could do:

highlight Green guifg=#008000
set statusline=%#Green#Foo