How can you convert this bash completion function to a zsh completion function?

Question

How can you convert this bash completion function to a zsh completion function?

This bash function allows you to tab-complete the names of directories above your current working directory so you can more quickly and accurately navigate up the file hierarchy.

Example:

$ pwd
/Users/me/Animals/Mammals/Ungulates/Goats/Ibex
$ upto Animals
$ pwd
/Users/me/Animals

Code:

function upto {
    if [[ -z $1 ]]; then
        return
    fi
    local upto=$1
    cd "${PWD/\/$upto\/*//$upto}"
}

_upto()
{
    local cur=${COMP_WORDS[COMP_CWORD]}
    local d=${PWD//\//\ }
    COMPREPLY=( $( compgen -W "$d" -- "$cur" ) )
}
complete -F _upto upto

I'd like to have a similar one in zsh, but I don't fully understand the mechanics of how this one works, much less how to modify it for zsh.

Answer 1

Try this completion function

_upto() {
    local parents;
    parents=(${(s:/:)PWD});
    compadd -V 'Parent Dirs' -- "${(Oa)parents[@]}";
 }

Enable it with compdef _upto upto.

Test it by creating a deply nested folder: f=/tmp/foo/bar/one/two/three;mkdir -p $f;cd $f. Typing upto <Tab> should give

three  two    one    bar    foo    tmp

To reverse the directories (i.e. start proposals at root rather at ..), remove the (Oa) flag from the compadd line.