posixpath.py 文件源码

def normpath(path):
    """Normalize path, eliminating double slashes, etc."""
    # Preserve unicode (if path is unicode)
    slash, dot = (u'/', u'.') if isinstance(path, _unicode) else ('/', '.')
    if path == '':
        return dot
    initial_slashes = path.startswith('/')
    # POSIX allows one or two initial slashes, but treats three or more
    # as single slash.
    if (initial_slashes and
        path.startswith('//') and not path.startswith('///')):
        initial_slashes = 2
    comps = path.split('/')
    new_comps = []
    for comp in comps:
        if comp in ('', '.'):
            continue
        if (comp != '..' or (not initial_slashes and not new_comps) or
             (new_comps and new_comps[-1] == '..')):
            new_comps.append(comp)
        elif new_comps:
            new_comps.pop()
    comps = new_comps
    path = slash.join(comps)
    if initial_slashes:
        path = slash*initial_slashes + path
    return path or dot