added initial async support (#20)

* added inital async setup

* update README.md

README.md

@@ -229,6 +229,8 @@ EOF
 ## TODO's
 Please create an issue/ pr if you want to see more functionality implemented
 - General
+  - [x] async support
+  - [ ] additional settings for components
   - [ ] create doc file
 - Components
   - [x] branch component

lua/lualine/async.lua

@@ -0,0 +1,75 @@
+local M = {}
+
+function M:new(args)
+  args = args or {}
+  for index, arg in pairs(args) do
+    self[index] = arg
+  end
+  setmetatable(args, self)
+  self.__index = self
+  return args
+end
+
+local function close_pipe(pipe)
+  if pipe ~= nil and not pipe:is_closing() then
+      pipe:close()
+  end
+end
+
+function M.close_all()
+  close_pipe(M.stdin)
+  close_pipe(M.stderr)
+  close_pipe(M.stdout)
+  close_pipe(M.handle)
+end
+
+function M.init_options()
+  local options = {}
+  local args  = vim.fn.split(M.cmd, ' ')
+  M.stdin = vim.loop.new_pipe(false)
+  M.stdout = vim.loop.new_pipe(false)
+  M.stderr = vim.loop.new_pipe(false)
+  options.command = table.remove(args, 1)
+  options.args = args
+  options.stdio = {
+    M.stdin,
+    M.stdout,
+    M.stderr
+  }
+  if M.cwd then
+    options.cwd = M.cwd
+  end
+  if M.env then
+    options.env = M.env
+  end
+  if M.detach then
+    options.detach = M.detach
+  end
+  return options
+end
+
+function M.start()
+  local options = M.init_options()
+  M.handle = vim.loop.spawn(options.command, options, vim.schedule_wrap(M.stop))
+  if M.on_stdout then
+      M.stdout:read_start(vim.schedule_wrap(M.on_stdout))
+  end
+  if M.on_stderr then
+      M.stderr:read_start(vim.schedule_wrap(M.on_stderr))
+  end
+end
+
+function M.stop(code, signal)
+  if M.on_exit then
+    M.on_exit(code, signal)
+  end
+  if M.on_stdout then
+      M.stdout:read_stop()
+  end
+  if M.on_stderr then
+      M.stderr:read_stop()
+  end
+  M.close_all()
+end
+
+return M

lua/lualine/components/branch.lua

@@ -1,11 +1,23 @@
-local function Branch()
-  local branch = vim.fn.systemlist(
-  'cd '..vim.fn.expand('%:p:h:S')..' 2>/dev/null && git status --porcelain -b 2>/dev/null')[1]
-  if not branch or #branch == 0 then
-    return ''
+local async = require('lualine.async')
+
+local branch
+
+local git_branch = async:new({
+  cmd = 'git branch --show-current',
+  on_stdout = function(_, data)
+    if data then
+      branch = data:gsub('\n', '')
     end
-  branch = branch:gsub([[^## No commits yet on (%w+)$]], '%1')
-  branch = branch:gsub([[^##%s+(%w+).*$]], '%1')
+  end
+})
+
+local timer = vim.loop.new_timer()
+timer:start(0, 1000, vim.schedule_wrap(function()
+  git_branch:start()
+end))
+
+local function Branch()
+  if not branch or #branch == 0 then return '' end
   local ok,devicons = pcall(require,'nvim-web-devicons')
   if ok then
     local icon = devicons.get_icon('git')