1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
|
# 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 = 2000
_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
if _parse_cache.has_key(key):
return _parse_cache[key]
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()
|
