# $Id$
# Copyright (c) 2000,2001 Peter B. West <pbwest@powerup.com.au>
# N.B  The following PATH manipulation functions
# 1) MUST NOT have a vertical bar `|' in any specified path
# 2) Handle the empty path "", but do not equate the empty path with "."

# These functions have been written to cope with spaces in the file paths.

# Clear path element given as arg from PATH
# N.B. path element MUST NOT contain a vertical bar `|'
rem_path() {
    if [ $# -lt 1 ]; then return; fi
    rem_vpath PATH "$@"
}

# Clear path element(s) given as arg 2 (3 ...) from the path named in arg1
# N.B. path element MUST NOT contain a vertical bar `|'
rem_vpath() {
    if [ $# -lt 2 ]; then return; fi
    eval _AP_=\"\$$1\"
    _P_=$1
    shift
    while [ $# -ge 1 ]; do
	_RP_="$1"
	shift
	_AP_=`echo $_AP_|
	sed ':loop
{s|:'"$_RP_"':|:|g
t loop
}
s|^'"$_RP_"':||
s|:'"$_RP_"'$||
s|^'"$_RP_"'$||'`
    eval $_P_=\"$_AP_\"
    done
    unset _AP_ _P_ _RP_
}

# To path named in $1, append path element arg(s), replacing all existing
# instances in the named path
# N.B. path elements MUST NOT contain a vertical bar `|'
app_vpath() {
    _VP_=$1; shift
    eval _VAL_=\"\$$_VP_\"
    for el
    do
	rem_vpath _VAL_ "$el"
	_VAL_="${_VAL_:+${_VAL_}:}$el"
    done
    eval ${_VP_}=\"$_VAL_\"
    export $_VP_
    unset _VP_ _VAL_
}

# Append path element(s) given as args to PATH, replacing all existing
# instances in the PATH
# N.B. path elements MUST NOT contain a vertical bar `|'
app_path() {
    app_vpath PATH "$@"
}

# To path named in $1, prepend path element arg(s), replacing all existing
# instances in the named path.  Elements will be appear in the PATH in
# argument order.
# N.B. path elements MUST NOT contain a vertical bar `|'
pre_vpath() {
    _VP_=$1; shift
    eval _VAL_=\"\$$_VP_\"
    _elx_=0
    while [ $# -gt 0 ]
    do
        _elx_=`expr $_elx_ + 1`
        eval _VAL_$_elx_=\"\$1\"
        shift
    done
    while [ $_elx_ -gt 0 ]
    do
        eval _el_=\"\$_VAL_$_elx_\"
        unset _VAL_$_elx_
        _elx_=`expr $_elx_ - 1`
	rem_vpath _VAL_ "$_el_"
	_VAL_="$_el_${_VAL_:+:${_VAL_}}"
    done
    eval ${_VP_}=\"$_VAL_\"
    export $_VP_
    unset _VP_ _VAL_
}

# Prepend path element(s) given as args to PATH, replacing all existing
# instances in the PATH.  N.B. elements will be appear in the PATH in
# REVERSE argument order.
# N.B. path elements MUST NOT contain a vertical bar `|'
pre_path() {
    pre_vpath PATH "$@"
}

# This function is no longer used.  Originally written for clean_vpath
# in order to process the arguments to pre_vpath in reverse order, it
# has been superseded by the modification to pre_vpath which processes
# its args in reverse order so that the argument list order will be
# preserved at the front of the path

# echo arguments in reverse order.  Args echoed are surrounded by
# single quotes - to provide these successfully to a subsequent function
# or command, submit the lot to an eval.
# E.g. eval command `reverse "arg 1" arg2 "This is arg 3"`
#  will supply three arguments to the echo.
# This will not preserve multiple spaces in the individal arguments.
# For that, use
# eval command "`reverse 'arg 1' arg2 'This is arg 3'`"
# I.e. use single quotes around the individual args, and surround the
# whole with double quotes; or
# var=`reverse "arg 1" arg2 "This is arg 3"`
# eval command "$var"

# This will BREAK if the arguments contain \<char> sequences which represent
# valid escaped characters, e.g. \\ or \t

# Variables used: _ix_ _o_ _v_ _stk_1 .. _stk_$#
reverseargs() {
    _ix_=0
    while [ $# -gt 0 ]
    do
        _ix_=`expr $_ix_ + 1`
        eval _stk_$_ix_=\"\$1\"
        shift
    done

    # No need to worry about the extra space at the beginning
    while [ $_ix_ -gt 0 ]
    do
        eval _v_=\"\$_stk_$_ix_\"
        unset _stk_$_ix_
        _o_="$_o_ '$_v_'"
        _ix_=`expr $_ix_ - 1`
    done

    echo "$_o_"
    unset _o_ _v_ _ix_
}

# Clean a path - run pre_vpath with every current element of the path
# in reverse order
# This removes all duplicates in the path, and leaves the first instance
# of a path element in its original relative place - later ones are deleted.
clean_vpath() {
    _CVP_=$1; shift
    # _CVP_ contains the name of the path
    eval _CVAL_=\"\$$_CVP_\"
    # _CVAL_ contains the value of the path
    _CVAL_=`echo "$_CVAL_"|sed 's/^/"/
s/:/" "/g
s/$/"/'`
    eval pre_vpath $_CVP_ "$_CVAL_"
    unset _CVAL_ _CVP_
}

clean_path() {
    clean_vpath PATH
}