zsh/Completion/Base/_subscript

#compdef -subscript-

local expl

if [[ "$PREFIX" = :* ]]; then
  _wanted characters expl 'character class' \
      compadd -p: -S ':]' alnum alpha blank cntrl digit graph \
                          lower print punct space upper xdigit
elif [[ ${(Pt)${compstate[parameter]}} = assoc* ]]; then
  local suf

  [[ "$RBUFFER" != \]* ]] && suf=']'

  _wanted association-keys expl 'association key' \
      compadd -S "$suf" -k "$compstate[parameter]"
elif [[ ${(Pt)${compstate[parameter]}} = array* ]]; then
  local list i j ret=1 disp

  _tags indexes parameters

  while _tags; do
    if _requested indexes; then
      ind=( {1..${#${(P)${compstate[parameter]}}}} )
      if zstyle -T ":completion:${curcontext}:indexes" verbose; then
        list=()
        for i in "$ind[@]"; do
          if [[ "$i" = ${PREFIX}*${SUFFIX} ]]; then
              list=( "$list[@]" 
	             "${i}:$(print -D ${(P)${compstate[parameter]}[$i]})" )
	  else
	      list=( "$list[@]" '' )
	  fi
        done
        zformat -a list ' -- ' "$list[@]"
	disp=( -d list)
      else
        disp=()
      fi

      if [[ "$RBUFFER" = \]* ]]; then
        _all_labels -V indexes expl 'array index' \
            compadd -S '' "$disp[@]" -a ind && ret=0
      else
        _all_labels -V indexes expl 'array index' \
            compadd -S ']' "$disp[@]" -a ind && ret=0
      fi
    fi
    _requested parameters && _parameters && ret=0

    (( ret )) || return 0
  done

  return 1
else
  _compalso -math-
fi