return absolute path in pure bash

bashrc

#get absolute path(shell)
abspath(){ #{{{
  local thePath
  if [[ ! "$1" =~ ^/ ]];then
    thePath="$PWD/$1"
  else
    thePath="$1"
  fi
  IFS=/ parr=($thePath)
  declare -a outp
  for i in "${parr[@]}";do
    case "$i" in
    ''|.) continue ;;
    ..)
      len=${#outp[@]}
      if ((len==0));then
        continue
      else
        unset outp[len-1] 
      fi
      ;;
    *)
      len=${#outp[@]}
      outp[len]=$i
      ;;
    esac
  done
  echo /"${outp[*]}"
} #}}}