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	The following adds support for RTSP (RFC2326) URLs to the standard urlparse.py module. (Augmented by FLD to include rtspu:, specified in the same RFC & OK'd by Anthony.)
		
			
				
	
	
		
			255 lines
		
	
	
	
		
			7.2 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			255 lines
		
	
	
	
		
			7.2 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
"""Parse (absolute and relative) URLs.
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See RFC 1808: "Relative Uniform Resource Locators", by R. Fielding,
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UC Irvine, June 1995.
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"""
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# Standard/builtin Python modules
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import string
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from string import join, split, rfind
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# A classification of schemes ('' means apply by default)
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uses_relative = ['ftp', 'http', 'gopher', 'nntp', 'wais', 'file',
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		 'https', 'shttp',
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		 'prospero', 'rtsp', 'rtspu', '']
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uses_netloc = ['ftp', 'http', 'gopher', 'nntp', 'telnet', 'wais',
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	       'file',
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	       'https', 'shttp', 'snews',
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	       'prospero', 'rtsp', 'rtspu', '']
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non_hierarchical = ['gopher', 'hdl', 'mailto', 'news', 'telnet', 'wais',
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		    'snews',
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		    ]
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uses_params = ['ftp', 'hdl', 'prospero', 'http',
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	       'https', 'shttp', 'rtsp', 'rtspu',
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	       '']
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uses_query = ['http', 'wais',
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	      'https', 'shttp',
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	      'gopher', 'rtsp', 'rtspu',
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	      '']
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uses_fragment = ['ftp', 'hdl', 'http', 'gopher', 'news', 'nntp', 'wais',
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		 'https', 'shttp', 'snews',
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		 'file', 'prospero', '']
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# Characters valid in scheme names
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scheme_chars = string.letters + string.digits + '+-.'
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MAX_CACHE_SIZE = 20
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_parse_cache = {}
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def clear_cache():
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	"""Clear the parse cache."""
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	global _parse_cache
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	_parse_cache = {}
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def urlparse(url, scheme = '', allow_fragments = 1):
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	"""Parse a URL into 6 components:
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	<scheme>://<netloc>/<path>;<params>?<query>#<fragment>
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	Return a 6-tuple: (scheme, netloc, path, params, query, fragment).
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	Note that we don't break the components up in smaller bits
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	(e.g. netloc is a single string) and we don't expand % escapes."""
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	key = url, scheme, allow_fragments
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	cached = _parse_cache.get(key, None)
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	if cached:
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		return cached
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	if len(_parse_cache) >= MAX_CACHE_SIZE:	# avoid runaway growth
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		clear_cache()
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	find = string.find
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	netloc = path = params = query = fragment = ''
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	i = find(url, ':')
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	if i > 0:
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		if url[:i] == 'http': # optimize the common case
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			scheme = string.lower(url[:i])
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			url = url[i+1:]
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			if url[:2] == '//':
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				i = find(url, '/', 2)
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				if i < 0:
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					i = len(url)
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				netloc = url[2:i]
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				url = url[i:]
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			if allow_fragments:
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				i = string.rfind(url, '#')
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				if i >= 0:
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					fragment = url[i+1:]
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					url = url[:i]
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			i = find(url, '?')
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			if i >= 0:
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				query = url[i+1:]
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				url = url[:i]
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			i = find(url, ';')
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			if i >= 0:
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				params = url[i+1:]
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				url = url[:i]
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			tuple = scheme, netloc, url, params, query, fragment
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			_parse_cache[key] = tuple
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			return tuple
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		for c in url[:i]:
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			if c not in scheme_chars:
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				break
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		else:
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			scheme, url = string.lower(url[:i]), url[i+1:]
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	if scheme in uses_netloc:
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		if url[:2] == '//':
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			i = find(url, '/', 2)
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			if i < 0:
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				i = len(url)
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			netloc, url = url[2:i], url[i:]
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	if allow_fragments and scheme in uses_fragment:
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		i = string.rfind(url, '#')
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		if i >= 0:
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			url, fragment = url[:i], url[i+1:]
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	if scheme in uses_query:
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		i = find(url, '?')
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		if i >= 0:
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			url, query = url[:i], url[i+1:]
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	if scheme in uses_params:
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		i = find(url, ';')
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		if i >= 0:
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			url, params = url[:i], url[i+1:]
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	tuple = scheme, netloc, url, params, query, fragment
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	_parse_cache[key] = tuple
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	return tuple
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def urlunparse((scheme, netloc, url, params, query, fragment)):
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	"""Put a parsed URL back together again.  This may result in a
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	slightly different, but equivalent URL, if the URL that was parsed
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	originally had redundant delimiters, e.g. a ? with an empty query
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	(the draft states that these are equivalent)."""
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	if netloc or (scheme in uses_netloc and url[:2] == '//'):
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		if url[:1] != '/': url = '/' + url
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		url = '//' + (netloc or '') + url
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	if scheme:
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		url = scheme + ':' + url
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	if params:
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		url = url + ';' + params
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	if query:
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		url = url + '?' + query
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	if fragment:
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		url = url + '#' + fragment
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	return url
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def urljoin(base, url, allow_fragments = 1):
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	"""Join a base URL and a possibly relative URL to form an absolute
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	interpretation of the latter."""
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	if not base:
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		return url
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	bscheme, bnetloc, bpath, bparams, bquery, bfragment = \
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		urlparse(base, '', allow_fragments)
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	scheme, netloc, path, params, query, fragment = \
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		urlparse(url, bscheme, allow_fragments)
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	if scheme != bscheme or scheme not in uses_relative:
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		return urlunparse((scheme, netloc, path,
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				   params, query, fragment))
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	if scheme in uses_netloc:
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		if netloc:
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			return urlunparse((scheme, netloc, path,
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					   params, query, fragment))
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		netloc = bnetloc
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	if path[:1] == '/':
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		return urlunparse((scheme, netloc, path,
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				   params, query, fragment))
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	if not path:
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		return urlunparse((scheme, netloc, bpath,
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				   params, query or bquery, fragment))
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	segments = split(bpath, '/')[:-1] + split(path, '/')
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	# XXX The stuff below is bogus in various ways...
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	if segments[-1] == '.':
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		segments[-1] = ''
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	while '.' in segments:
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		segments.remove('.')
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	while 1:
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		i = 1
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		n = len(segments) - 1
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		while i < n:
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			if segments[i] == '..' and segments[i-1]:
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				del segments[i-1:i+1]
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				break
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			i = i+1
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		else:
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			break
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	if len(segments) == 2 and segments[1] == '..' and segments[0] == '':
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		segments[-1] = ''
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	elif len(segments) >= 2 and segments[-1] == '..':
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		segments[-2:] = ['']
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	return urlunparse((scheme, netloc, join(segments, '/'),
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			   params, query, fragment))
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def urldefrag(url):
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	"""Removes any existing fragment from URL.
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	Returns a tuple of the defragmented URL and the fragment.  If
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	the URL contained no fragments, the second element is the
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	empty string.
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	"""
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	s, n, p, a, q, frag = urlparse(url)
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	defrag = urlunparse((s, n, p, a, q, ''))
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	return defrag, frag
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test_input = """
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      http://a/b/c/d
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      g:h        = <URL:g:h>
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      http:g     = <URL:http://a/b/c/g>
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      http:      = <URL:http://a/b/c/d>
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      g          = <URL:http://a/b/c/g>
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      ./g        = <URL:http://a/b/c/g>
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      g/         = <URL:http://a/b/c/g/>
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      /g         = <URL:http://a/g>
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      //g        = <URL:http://g>
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      ?y         = <URL:http://a/b/c/d?y>
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      g?y        = <URL:http://a/b/c/g?y>
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      g?y/./x    = <URL:http://a/b/c/g?y/./x>
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      .          = <URL:http://a/b/c/>
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      ./         = <URL:http://a/b/c/>
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      ..         = <URL:http://a/b/>
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      ../        = <URL:http://a/b/>
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      ../g       = <URL:http://a/b/g>
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      ../..      = <URL:http://a/>
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      ../../g    = <URL:http://a/g>
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      ../../../g = <URL:http://a/../g>
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      ./../g     = <URL:http://a/b/g>
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      ./g/.      = <URL:http://a/b/c/g/>
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      /./g       = <URL:http://a/./g>
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      g/./h      = <URL:http://a/b/c/g/h>
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      g/../h     = <URL:http://a/b/c/h>
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      http:g     = <URL:http://a/b/c/g>
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      http:      = <URL:http://a/b/c/d>
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      http:?y         = <URL:http://a/b/c/d?y>
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      http:g?y        = <URL:http://a/b/c/g?y>
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      http:g?y/./x    = <URL:http://a/b/c/g?y/./x>
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"""
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# XXX The result for //g is actually http://g/; is this a problem?
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def test():
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	import sys
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	base = ''
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	if sys.argv[1:]:
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		fn = sys.argv[1]
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		if fn == '-':
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			fp = sys.stdin
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		else:
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			fp = open(fn)
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	else:
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		import StringIO
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		fp = StringIO.StringIO(test_input)
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	while 1:
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		line = fp.readline()
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		if not line: break
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		words = string.split(line)
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		if not words:
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			continue
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		url = words[0]
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		parts = urlparse(url)
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		print '%-10s : %s' % (url, parts)
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		abs = urljoin(base, url)
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		if not base:
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			base = abs
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		wrapped = '<URL:%s>' % abs
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		print '%-10s = %s' % (url, wrapped)
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		if len(words) == 3 and words[1] == '=':
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			if wrapped != words[2]:
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				print 'EXPECTED', words[2], '!!!!!!!!!!'
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if __name__ == '__main__':
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	test()
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