#

# DIRECTORY MANIPULATION FUNCTIONS PUSHD, POPD AND DIRS

#

# Uses global parameters _push_max _push_top _push_stack

integer _push_max=100 _push_top=100

# Display directory stack -- $HOME displayed as ~

function dirs

{

    typeset dir="${PWD#$HOME/}"

    case $dir in

    $HOME)

        dir=\~

        ;;

    /*) ;;

    *)  dir=\~/$dir

    esac

    print -r - "$dir ${_push_stack[@]}"

}

# Change directory and put directory on front of stack

function pushd

{

    typeset dir= type=0

    integer i

    case $1 in

    "") # pushd

        if    ((_push_top >= _push_max))

        then  print pushd: No other directory.

              return 1

        fi

        type=1 dir=${_push_stack[_push_top]}

        ;;

    +[1-9]|+[1-9][0-9]) # pushd +n

        integer i=_push_top$1-1

        if    ((i >= _push_max))

        then  print pushd: Directory stack not that deep.

              return 1

        fi

        type=2 dir=${_push_stack[i]}

        ;;

    *)  if    ((_push_top <= 0))

        then  print pushd: Directory stack overflow.

              return 1

        fi

    esac

    case $dir in

    \~*)   dir=$HOME${dir#\~}

    esac

    cd "${dir:-$1}" > /dev/null || return 1

    dir=${OLDPWD#$HOME/}

    case $dir in

    $HOME)

        dir=\~

        ;;

    /*) ;;

    *)  dir=\~/$dir

    esac

    case $type in

    0)  # pushd name

        _push_stack[_push_top=_push_top-1]=$dir

        ;;

    1)  # pushd

        _push_stack[_push_top]=$dir

        ;;

    2)  # push +n

        type=${1#+} i=_push_top-1

        set -- "${_push_stack[@]}" "$dir" "${_push_stack[@]}"

        shift $type

        for dir

        do  (((i=i+1) < _push_max)) || break

            _push_stack[i]=$dir

        done

    esac

    dirs

}

# Pops the top directory

function popd

{

    typeset dir

    if    ((_push_top >= _push_max))

    then  print popd: Nothing to pop.

          return 1

    fi

    case $1 in  

    "")

        dir=${_push_stack[_push_top]}

        case $dir in

        \~*)   dir=$HOME${dir#\~}

        esac

        cd "$dir" || return 1

        ;;

    +[1-9]|+[1-9][0-9])

        typeset savedir

        integer i=_push_top$1-1

        if    ((i >= _push_max))

        then  print pushd: Directory stack not that deep.

              return 1

        fi

        while ((i > _push_top))

        do _push_stack[i]=${_push_stack[i-1]}

              i=i-1

        done

        ;;

    *)  print pushd: Bad directory.

        return 1

    esac

    unset '_push_stack[_push_top]'

    _push_top=_push_top+1

    dirs

}