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cpython/Lib/urlparse.py
Guido van Rossum 7449540986 After some discussion with Jeremy and Fred, decided to limit the
default urlparse cache size to 20 instead of 2000.  The main use of
the cache seems to be to gain some speed in Grail, which is calling
urljoin with the same base for each anchor.  2000 is a bit too big for
Jeremy, who doesn't need the cache at all.  20 should keep at least
95% of the Grail speedup while wasting an insignificant amount of
memory in Jeremy's application.
1997-07-14 19:08:15 +00:00

234 lines
6.6 KiB
Python

# Parse (absolute and relative) URLs. See RFC 1808: "Relative Uniform
# Resource Locators", by R. Fielding, UC Irvine, June 1995.
# Standard/builtin Python modules
import string
from string import joinfields, splitfields, find, rfind
# A classification of schemes ('' means apply by default)
uses_relative = ['ftp', 'http', 'gopher', 'nntp', 'wais', 'file',
'https', 'shttp',
'prospero', '']
uses_netloc = ['ftp', 'http', 'gopher', 'nntp', 'telnet', 'wais',
'https', 'shttp', 'snews',
'prospero', '']
non_hierarchical = ['gopher', 'hdl', 'mailto', 'news', 'telnet', 'wais',
'snews',
]
uses_params = ['ftp', 'hdl', 'prospero', 'http',
'https', 'shttp',
'']
uses_query = ['http', 'wais',
'https', 'shttp',
'']
uses_fragment = ['ftp', 'hdl', 'http', 'gopher', 'news', 'nntp', 'wais',
'https', 'shttp', 'snews',
'file', 'prospero', '']
# Characters valid in scheme names
scheme_chars = string.letters + string.digits + '+-.'
MAX_CACHE_SIZE = 20
_parse_cache = {}
def clear_cache():
"""Clear the parse cache."""
global _parse_cache
_parse_cache = {}
# 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.
def urlparse(url, scheme = '', allow_framents = 1):
key = url, scheme, allow_framents
try:
return _parse_cache[key]
except KeyError:
pass
if len(_parse_cache) >= MAX_CACHE_SIZE: # avoid runaway growth
clear_cache()
netloc = path = params = query = fragment = ''
i = string.find(url, ':')
if i > 0:
for c in url[:i]:
if c not in scheme_chars:
break
else:
scheme, url = string.lower(url[:i]), url[i+1:]
if scheme in uses_netloc:
if url[:2] == '//':
i = string.find(url, '/', 2)
if i < 0:
i = len(url)
netloc, url = url[2:i], url[i:]
if allow_framents and scheme in uses_fragment:
i = string.rfind(url, '#')
if i >= 0:
url, fragment = url[:i], url[i+1:]
if scheme in uses_query:
i = string.find(url, '?')
if i >= 0:
url, query = url[:i], url[i+1:]
if scheme in uses_params:
i = string.find(url, ';')
if i >= 0:
url, params = url[:i], url[i+1:]
tuple = scheme, netloc, url, params, query, fragment
_parse_cache[key] = tuple
return tuple
# 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).
def urlunparse((scheme, netloc, url, params, query, fragment)):
if netloc:
if url[:1] != '/': url = '/' + url
url = '//' + netloc + url
if scheme:
url = scheme + ':' + url
if params:
url = url + ';' + params
if query:
url = url + '?' + query
if fragment:
url = url + '#' + fragment
return url
# Join a base URL and a possibly relative URL to form an absolute
# interpretation of the latter.
def urljoin(base, url, allow_framents = 1):
if not base:
return url
bscheme, bnetloc, bpath, bparams, bquery, bfragment = \
urlparse(base, '', allow_framents)
scheme, netloc, path, params, query, fragment = \
urlparse(url, bscheme, allow_framents)
# XXX Unofficial hack: default netloc to bnetloc even if
# schemes differ
if scheme != bscheme and not netloc and \
scheme in uses_relative and bscheme in uses_relative and \
scheme in uses_netloc and bscheme in uses_netloc:
netloc = bnetloc
# Strip the port number
i = find(netloc, '@')
if i < 0: i = 0
i = find(netloc, ':', i)
if i >= 0:
netloc = netloc[:i]
if scheme != bscheme or scheme not in uses_relative:
return urlunparse((scheme, netloc, path,
params, query, fragment))
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:
return urlunparse((scheme, netloc, bpath,
params, query or bquery, fragment))
i = rfind(bpath, '/')
if i >= 0:
path = bpath[:i] + '/' + path
segments = splitfields(path, '/')
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]:
del segments[i-1:i+1]
break
i = i+1
else:
break
if len(segments) >= 2 and segments[-1] == '..':
segments[-2:] = ['']
return urlunparse((scheme, netloc, joinfields(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.
"""
s, n, p, a, q, frag = urlparse(url)
defrag = urlunparse((s, n, p, a, q, ''))
return defrag, frag
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>
"""
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 = string.split(line)
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()