#!/bin/sh
#
# Sed portability notes
# - SuSv3
#    - Only -e, -f, and -n are standard options
# - Linux
#    - -i argument is of the form -i[ext]
#    - extended regular expressions argument is -r
# - Mac OSX
#    - -i argument is of the form -i [ext]
#    - extended regular expressions argument is -E
#
# Here we support a limited subset of the available sed capabilities,
# ensuring that all those supported by this script can be utilized
# regardless of the current platform.
#
# We accept -n, -e, -f, and -i with no backup extension.  We support
# extended regular expressions using the -r argument.  Note that extended
# regular expressions support may not be retained, depending upon the
# capabilities of the other platforms we wish to support, and we may need
# to reimplement -i internally in this script on some platforms.


realbin() {
     _script=`basename $0`
     found=
     for bin in `which -a $_script`; do
          if ! cmp -s $bin $0; then
                found=$bin
                break
          fi
     done
     if [ -n "$found" ]; then
          echo "$found"
     else
          return 1
     fi
}

quote(){
    /usr/bin/sed -e "s,','\\\\'',g; 1s,^,',; \$s,\$,',;" << EOF
$1
EOF
}

save () {
    case "$1" in
    # when a string contains a "'" we have to escape it
    *\'*)
        saved="$saved `quote "$1"`"
        ;;
    # otherwise just quote the variable
    *)
        saved="$saved '$1'"
        ;;
    esac
}

case `uname -s` in
    Darwin)
        inplace_arg="-i ''"
        extended_re_arg="-E"
        getopt_os="ir"
        ;;
    Linux)
        inplace_arg="-i"
        extended_re_arg="-r"
        getopt_os="ir"
        ;;
esac

saved=""
while getopts ne:f:$getopt_os opt; do
    case "$opt" in
        n)
            save "-$opt"
            ;;
        e|f)
            save "-$opt"
            save "$OPTARG"
            ;;
        i)
            saved="$saved $inplace_arg"
            continue
            ;;
        r)
            saved="$saved $extended_re_arg"
            continue
            ;;
        \?)
            echo >&2 "Unsupported argument: $OPTARG"
            exit 1
            ;;
    esac
done
shift $(($OPTIND - 1))
for arg; do
    save "$arg"
done

eval set -- "$saved"
exec `realbin` "$@"