a wrapper of asyncrun that respects modeline-like setting in file

asyncrun.lua

-- inlinecmd
-- b:asyncrun_plaincmd

local M = {}

local inlinecmd_magic = "# asyncrun: "
local plaincmd_varname = "asyncrun_plaincmd"

local find_inlinecmd = function(bufnr)
  local _reversed_lines = function(high)
    local start = high + 1
    return function()
      -- high, high+1 -> 0, 1
      start = start - 1
      if start >= 0 then
        local lines = vim.api.nvim_buf_get_lines(bufnr, start, start + 1, true)
        return lines[1]
      end
    end
  end

  local _find = function(line)
    local pos = string.find(line, inlinecmd_magic)
    if pos ~= nil then
      return string.sub(line, pos + string.len(inlinecmd_magic))
    end
  end

  local high = vim.api.nvim_buf_line_count(bufnr) - 1

  for line in _reversed_lines(high) do
    local cmd = _find(line)
    if cmd ~= nil then
      return cmd
    end
  end
end

local finalcmd = function(bufnr)
  local inlinecmd = find_inlinecmd(bufnr)
  if inlinecmd ~= nil then
    return inlinecmd
  end

  if vim.fn.exists("b:" .. plaincmd_varname) == 1 then
    local plaincmd = vim.api.nvim_buf_get_var(bufnr, plaincmd_varname)
    if plaincmd ~= nil then
      return plaincmd
    end
  end
end

M.main = function()
  local bufnr = 0
  local cmd = finalcmd(bufnr)
  if cmd == nil then
    print("no cmd available")
    return
  end

  vim.cmd("AsyncRun " .. cmd .. " %:p")
end

return M