I want to emulate ultisnips behaviour where only if exact snippet is typed out and you press tab it expands.
(if I have foo => blabla if I type fo it should open ultisnips, if I have foo => blabla).
I need to do

        ['<Tab>'] = {
  function(cmp)
      local exact_snippet = cmp.get_selected_item().label == cmp.get_current_input() -- get_current_input does not exist
      if cmp.snippet_active() then return cmp.accept()
      elseif exact_snippet then return cmp.select_and_accept() end
      return false
[...]

or something like that ? But I need a way to be sure the "current input" of the user is exactly the snippet.
How to do such thing