fs.subr

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# Sed script to normalize a path.
#
# This is constructed in multiple steps for documentation purposes only;
# we could just as well provide this as a one-liner within the
# shtk_fs_normalize_path function... but the result is unreadable.
#
# 1st: Strip off any trailing . component and its associated slash.
_Shtk_Fs_Normalize="s,/\.$,,"
# 2nd: Collapse multiple consecutive slashes.
_Shtk_Fs_Normalize="${_Shtk_Fs_Normalize};s,/+,/,g"
# 3rd: Collapse any intermediate . components.
_Shtk_Fs_Normalize="${_Shtk_Fs_Normalize};s,/\./,/,g"
# 4th: Remove trailing slashes.
_Shtk_Fs_Normalize="${_Shtk_Fs_Normalize};/[^/]/s,/$,,"
# 5th: If the path is relative and does not already start with ., add it.
_Shtk_Fs_Normalize="${_Shtk_Fs_Normalize};/^[./]/!s,^,./,"


shtk_fs_join_paths() {
    local result="${1}"; shift
    while [ ${#} -gt 0 ]; do
        result="${result}/${1}"
        shift
    done
    shtk_fs_normalize_path "${result}"
}


shtk_fs_normalize_path() {
    local unnormalized="${1}"; shift
    echo "${unnormalized}" | sed -E "${_Shtk_Fs_Normalize}" \
        || shtk_abort "sed script failed in call to shtk_fs_normalize_path" \
                      "most likely a portability bug"
}