Collapse directories in zsh prompt in a unique way

Question

Is there a way to collapse the current working directory in the zsh prompt in a unique way, so that I could copy and paste it to another terminal, hit TAB and get the original path?

Let's say we have following directories:

/adam/devl
/alice/devl
/alice/docs
/bob/docs

If the prompt is programmed to show the first characters, and I'm in /b/d, then it is unique. On the other hand, /a/d is not unique, so I would need /ad/d, /al/de and /al/do. And even /ali/… as soon as the user alex appears.

Is it possible to hack this directly in zsh or do I need to write a script, that finds the shortest unique beginning of each parent directory?

Thank you for your ideas!

Answer 1

I'm not aware that zsh has a built-in function of this sort, but it should be pretty easy to script without resorting to a single subshell or slow pipe:

#!/bin/zsh

paths=(${(s:/:)PWD})

cur_path='/'
cur_short_path='/'
for directory in ${paths[@]}
do
  cur_dir=''
  for (( i=0; i<${#directory}; i++ )); do
    cur_dir+="${directory:$i:1}"
    matching=("$cur_path"/"$cur_dir"*/)
    if [[ ${#matching[@]} -eq 1 ]]; then
      break
    fi
  done
  cur_short_path+="$cur_dir/"
  cur_path+="$directory/"
done

printf %q "${cur_short_path: : -1}"
echo

This script will output the shortest path needed for auto-completion to work.

You can throw it in your .zshrc as a function and then run it from any directory.

function spwd {
  paths=(${(s:/:)PWD})

  cur_path='/'
  cur_short_path='/'
  for directory in ${paths[@]}
  do
    cur_dir=''
    for (( i=0; i<${#directory}; i++ )); do
      cur_dir+="${directory:$i:1}"
      matching=("$cur_path"/"$cur_dir"*/)
      if [[ ${#matching[@]} -eq 1 ]]; then
        break
      fi
    done
    cur_short_path+="$cur_dir/"
    cur_path+="$directory/"
  done

  printf %q "${cur_short_path: : -1}"
  echo
}

Here's a video of it in action:

https://asciinema.org/a/0TyL8foqvQ8ec5ZHS3c1mn5LH

Or if you prefer, some sample output:

~/t $ ls
adam  alice  bob  getshortcwd.zsh

~/t $ ls adam
devl

~/t $ ls alice
devl  docs

~/t $ spwd
/h/v/t

~/t $ cd adam/devl

~/t/adam/devl $ spwd
/h/v/t/ad/d

~/t/adam/devl $ cd ../../alice/devl

~/t/alice/devl $ spwd
/h/v/t/al/de

~/t/alice/devl $ cd ../docs

~/t/alice/docs $ spwd
/h/v/t/al/do

~/t/alice/docs $ `spwd` [TAB]
~/t/alice/docs $ /h/v/t/al/do [TAB]
~/t/alice/docs $ /home/vsimonian/t/alice/docs