List files without stopping to type in zsh

tab_list_files_zsh.sh

# List files in zsh with <TAB>
#
# Copyleft 2017 by Ignacio Nunez Hernanz <nacho _a_t_ ownyourbits _d_o_t_ com>
# GPL licensed (see end of file) * Use at your own risk!
#
# Usage:
#   In the middle of the command line:
#     (command being typed)<TAB>(resume typing)
#
#   At the beginning of the command line:
#     <SPACE><TAB>
#     <SPACE><SPACE><TAB>
#
# Notes:
#   This does not affect other completions
#   If you want 'cd ' or './' to be prepended, write in your .zshrc 'export TAB_LIST_FILES_PREFIX'
#   I recommend to complement this with push-line-or edit (bindkey '^q' push-line-or-edit)
function tab_list_files
{
  if [[ $#BUFFER == 0 ]]; then
    BUFFER="ls "
    CURSOR=3
    zle list-choices
    zle backward-kill-word
  elif [[ $BUFFER =~ ^[[:space:]][[:space:]].*$ ]]; then
    BUFFER="./"
    CURSOR=2
    zle list-choices
    [ -z ${TAB_LIST_FILES_PREFIX+x} ] && BUFFER="  " CURSOR=2
  elif [[ $BUFFER =~ ^[[:space:]]*$ ]]; then
    BUFFER="cd "
    CURSOR=3
    zle list-choices
    [ -z ${TAB_LIST_FILES_PREFIX+x} ] && BUFFER=" " CURSOR=1
  else
    BUFFER_=$BUFFER
    CURSOR_=$CURSOR
    zle expand-or-complete || zle expand-or-complete || {
      BUFFER="ls "
      CURSOR=3
      zle list-choices
      BUFFER=$BUFFER_
      CURSOR=$CURSOR_
    }
  fi
}
zle -N tab_list_files
bindkey '^I' tab_list_files

# uncomment the following line to prefix 'cd ' and './' 
# when listing dirs and executables respectively
#export TAB_LIST_FILES_PREFIX

# these two lines are usually included by oh-my-zsh, but just in case
autoload -Uz compinit
compinit

# uncomment the following line to complement tab_list_files with ^q
#bindkey '^q' push-line-or-edit

# License
#
# This script is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This script is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this script; if not, write to the
# Free Software Foundation, Inc., 59 Temple Place, Suite 330,
# Boston, MA  02111-1307  USA