"""Parse (absolute and relative) URLs.See RFC 1808: "Relative Uniform Resource Locators", by R. Fielding,UC Irvine, June 1995."""__all__ = ["urlparse", "urlunparse", "urljoin", "urldefrag",           "urlsplit", "urlunsplit"]# A classification of schemes ('' means apply by default)uses_relative = ['ftp', 'http', 'gopher', 'nntp', 'wais', 'file',                 'https', 'shttp',                 'prospero', 'rtsp', 'rtspu', '']uses_netloc = ['ftp', 'http', 'gopher', 'nntp', 'telnet', 'wais',               'file',               'https', 'shttp', 'snews',               'prospero', 'rtsp', 'rtspu', '']non_hierarchical = ['gopher', 'hdl', 'mailto', 'news', 'telnet', 'wais',                    'snews', 'sip',                    ]uses_params = ['ftp', 'hdl', 'prospero', 'http',               'https', 'shttp', 'rtsp', 'rtspu', 'sip',               '']uses_query = ['http', 'wais',              'https', 'shttp',              'gopher', 'rtsp', 'rtspu', 'sip',              '']uses_fragment = ['ftp', 'hdl', 'http', 'gopher', 'news', 'nntp', 'wais',                 'https', 'shttp', 'snews',                 'file', 'prospero', '']# Characters valid in scheme namesscheme_chars = ('abcdefghijklmnopqrstuvwxyz'                'ABCDEFGHIJKLMNOPQRSTUVWXYZ'                '0123456789'                '+-.')MAX_CACHE_SIZE = 20_parse_cache = {}def clear_cache():    """Clear the parse cache."""    global _parse_cache    _parse_cache = {}def urlparse(url, scheme='', allow_fragments=1):    """Parse a URL into 6 components:    <scheme>://<netloc>/<path>;<params>?<query>#<fragment>    Return a 6-tuple: (scheme, netloc, path, params, query, fragment).    Note that we don't break the components up in smaller bits    (e.g. netloc is a single string) and we don't expand % escapes."""    tuple = urlsplit(url, scheme, allow_fragments)    scheme, netloc, url, query, fragment = tuple    if scheme in uses_params and ';' in url:        url, params = _splitparams(url)    else:        params = ''    return scheme, netloc, url, params, query, fragmentdef _splitparams(url):    if '/'  in url:        i = url.find(';', url.rfind('/'))        if i < 0:            return url, ''    else:        i = url.find(';')    return url[:i], url[i+1:]def urlsplit(url, scheme='', allow_fragments=1):    """Parse a URL into 5 components:    <scheme>://<netloc>/<path>?<query>#<fragment>    Return a 5-tuple: (scheme, netloc, path, query, fragment).    Note that we don't break the components up in smaller bits    (e.g. netloc is a single string) and we don't expand % escapes."""    key = url, scheme, allow_fragments    cached = _parse_cache.get(key, None)    if cached:        return cached    if len(_parse_cache) >= MAX_CACHE_SIZE: # avoid runaway growth        clear_cache()    netloc = query = fragment = ''    i = url.find(':')    if i > 0:        if url[:i] == 'http': # optimize the common case            scheme = url[:i].lower()            url = url[i+1:]            if url[:2] == '//':                i = url.find('/', 2)                if i < 0:                    i = url.find('#')                    if i < 0:                        i = len(url)                netloc = url[2:i]                url = url[i:]            if allow_fragments and '#' in url:                url, fragment = url.split('#', 1)            if '?' in url:                url, query = url.split('?', 1)            tuple = scheme, netloc, url, query, fragment            _parse_cache[key] = tuple            return tuple        for c in url[:i]:            if c not in scheme_chars:                break        else:            scheme, url = url[:i].lower(), url[i+1:]    if scheme in uses_netloc:        if url[:2] == '//':            i = url.find('/', 2)            if i < 0:                i = len(url)            netloc, url = url[2:i], url[i:]    if allow_fragments and scheme in uses_fragment and '#' in url:        url, fragment = url.split('#', 1)    if scheme in uses_query and '?' in url:        url, query = url.split('?', 1)    tuple = scheme, netloc, url, query, fragment    _parse_cache[key] = tuple    return tupledef urlunparse((scheme, netloc, url, params, query, fragment)):    """Put a parsed URL back together again.  This may result in a    slightly different, but equivalent URL, if the URL that was parsed    originally had redundant delimiters, e.g. a ? with an empty query    (the draft states that these are equivalent)."""    if params:        url = "%s;%s" % (url, params)    return urlunsplit((scheme, netloc, url, query, fragment))def urlunsplit((scheme, netloc, url, query, fragment)):    if netloc or (scheme and scheme in uses_netloc and url[:2] != '//'):        if url and url[:1] != '/': url = '/' + url        url = '//' + (netloc or '') + url    if scheme:        url = scheme + ':' + url    if query:        url = url + '?' + query    if fragment:        url = url + '#' + fragment    return urldef urljoin(base, url, allow_fragments = 1):    """Join a base URL and a possibly relative URL to form an absolute    interpretation of the latter."""    if not base:        return url    if not url:        return base    bscheme, bnetloc, bpath, bparams, bquery, bfragment = \            urlparse(base, '', allow_fragments)    scheme, netloc, path, params, query, fragment = \            urlparse(url, bscheme, allow_fragments)    if scheme != bscheme or scheme not in uses_relative:        return url    if scheme in uses_netloc:        if netloc:            return urlunparse((scheme, netloc, path,                               params, query, fragment))        netloc = bnetloc    if path[:1] == '/':        return urlunparse((scheme, netloc, path,                           params, query, fragment))    if not path:        if not params:            params = bparams            if not query:                query = bquery        return urlunparse((scheme, netloc, bpath,                           params, query, fragment))    segments = bpath.split('/')[:-1] + path.split('/')    # XXX The stuff below is bogus in various ways...    if segments[-1] == '.':        segments[-1] = ''    while '.' in segments:        segments.remove('.')    while 1:        i = 1        n = len(segments) - 1        while i < n:            if (segments[i] == '..'                and segments[i-1] not in ('', '..')):                del segments[i-1:i+1]                break            i = i+1        else:            break    if segments == ['', '..']:        segments[-1] = ''    elif len(segments) >= 2 and segments[-1] == '..':        segments[-2:] = ['']    return urlunparse((scheme, netloc, '/'.join(segments),                       params, query, fragment))def urldefrag(url):    """Removes any existing fragment from URL.    Returns a tuple of the defragmented URL and the fragment.  If    the URL contained no fragments, the second element is the    empty string.    """    if '#' in url:        s, n, p, a, q, frag = urlparse(url)        defrag = urlunparse((s, n, p, a, q, ''))        return defrag, frag    else:        return url, ''test_input = """      http://a/b/c/d      g:h        = <URL:g:h>      http:g     = <URL:http://a/b/c/g>      http:      = <URL:http://a/b/c/d>      g          = <URL:http://a/b/c/g>      ./g        = <URL:http://a/b/c/g>      g/         = <URL:http://a/b/c/g/>      /g         = <URL:http://a/g>      //g        = <URL:http://g>      ?y         = <URL:http://a/b/c/d?y>      g?y        = <URL:http://a/b/c/g?y>      g?y/./x    = <URL:http://a/b/c/g?y/./x>      .          = <URL:http://a/b/c/>      ./         = <URL:http://a/b/c/>      ..         = <URL:http://a/b/>      ../        = <URL:http://a/b/>      ../g       = <URL:http://a/b/g>      ../..      = <URL:http://a/>      ../../g    = <URL:http://a/g>      ../../../g = <URL:http://a/../g>      ./../g     = <URL:http://a/b/g>      ./g/.      = <URL:http://a/b/c/g/>      /./g       = <URL:http://a/./g>      g/./h      = <URL:http://a/b/c/g/h>      g/../h     = <URL:http://a/b/c/h>      http:g     = <URL:http://a/b/c/g>      http:      = <URL:http://a/b/c/d>      http:?y         = <URL:http://a/b/c/d?y>      http:g?y        = <URL:http://a/b/c/g?y>      http:g?y/./x    = <URL:http://a/b/c/g?y/./x>"""# XXX The result for //g is actually http://g/; is this a problem?def test():    import sys    base = ''    if sys.argv[1:]:        fn = sys.argv[1]        if fn == '-':            fp = sys.stdin        else:            fp = open(fn)    else:        import StringIO        fp = StringIO.StringIO(test_input)    while 1:        line = fp.readline()        if not line: break        words = line.split()        if not words:            continue        url = words[0]        parts = urlparse(url)        print '%-10s : %s' % (url, parts)        abs = urljoin(base, url)        if not base:            base = abs        wrapped = '<URL:%s>' % abs        print '%-10s = %s' % (url, wrapped)        if len(words) == 3 and words[1] == '=':            if wrapped != words[2]:                print 'EXPECTED', words[2], '!!!!!!!!!!'if __name__ == '__main__':    test()