zsh/Completion/Core/_all_labels

#autoload

local __gopt=-J __len __tmp __pre __suf __ret=1 __descr __spec __prev

if [[ "$1" = - ]]; then
  __prev=-
  shift
fi

if [[ "$1" = -([12]|)[VJ] ]]; then
  __gopt="$1"
  shift
fi

__tmp=${argv[(ib:4:)-]}
__len=$#
if [[ __tmp -lt __len ]]; then
  __pre=$(( __tmp-1 ))
  __suf=$__tmp
elif [[ __tmp -eq $# ]]; then
  __pre=-2
  __suf=$(( __len+1 ))
else
  __pre=4
  __suf=5
fi

while comptags "-A$__prev" "$1" curtag __spec; do
  _comp_tags="$_comp_tags $__spec "
  if [[ "$curtag" = *:* ]]; then
    zformat -f __descr "${curtag#*:}" "d:$3"
    _description "$__gopt" "${curtag%:*}" "$2" "$__descr"
    curtag="${curtag%:*}"

    "$4" "${(P@)2}" "${(@)argv[5,-1]}" && __ret=0
  else
    _description "$__gopt" "$curtag" "$2" "$3"

    "${(@)argv[4,__pre]}" "${(P@)2}" "${(@)argv[__suf,-1]}" && __ret=0
  fi
done

return __ret