checkio (URL Normalization)
URL normalization is the process by which URLs are modified and standardized in a consistent manner. The goal of the normalization process is to transform a URL into a normalized or canonical URL so it is possible to determine if two syntactically different URLs may be equivalent.
For our normalization we will use normalizations that preserve semantics. You should normalize a given url using the next rules (only these rules. They are slightly different from RFC).
Normalization Rules:
- 1. Converting the url to lower case (excepting letters in escape sequences).
HTTP://www.Example.com/ → http://www.example.com/ - 2. Capitalizing letters in escape sequences. All letters within a percent-encoding triplet (e.g., "%3B") are case-insensitive, and should be capitalized.
http://www.example.com/a%c2%b1b → http://www.example.com/a%C2%B1b - 3. Decoding percent-encoded octets of unreserved characters. For consistency, percent-encoded octets in the ranges of ALPHA (%41–%5A and %61–%7A), DIGIT (%30–%39), hyphen (%2D), period (%2E), underscore (%5F), or tilde (%7E) should not be created by URI producers and, when found in a URI, should be decoded to their corresponding unreserved characters by URI normalizers. Don't forget about 1st rule after it.
http://www.example.com/%7Eusername/ → http://www.example.com/~username/ - 4. Removing the default port. The default port (port 80 for the “http” scheme) should be removed from a URL.
http://www.example.com:80/bar.html → http://www.example.com/bar.html - 5. Removing dot-segments. The segments “..” and “.” can be removed from a URL according to the algorithm described in RFC 3986 (or a similar algorithm). ".." is a parent directory, "." is the same directory.
http://www.example.com/a/b/../c/./d.html → http://www.example.com/a/c/d.html
Additional links: If you are interested to know more about URL normalization (This is not necessarily for this task), then you can find more information here: Wikipedia, RFC3986
Precondition: All input urls are valid.
Input: URL, an unicode string.
Output: Normalized URL, a string.
Example:
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checkio("Http://Www.Checkio.org")=="http://www.checkio.org"
checkio("http://www.checkio.org/%cc%b1bac")=="http://www.checkio.org/%CC%B1bac"
checkio("http://www.checkio.org/task%5F%31")=="http://www.checkio.org/task_1"
checkio("http://www.checkio.org:80/home/")=="http://www.checkio.org/home/"
checkio("http://www.checkio.org:8080/home/")=="http://www.checkio.org:8080/home/"
checkio("http://www.checkio.org/task/./1/../2/././name")=="http://www.checkio.org/task/ 2/name
"
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URL Normalization，各种细节，处理起来略复杂
def checkio(url):
url = url.lower().replace(':8080', ':08080')
url = url.replace('%2d', '-').replace('%2e', '.').replace('%5f', '_').replace('%7e', '~').replace(':80', '').replace(':08080', ':8080')
data = url.split('%')
for i in range(len(data)):
try:
char = int(data[i][:2], 16)
if (char >= 65 and char <= 91) or (char >= 97 and char <= 122) or (char >= 48 and char <= 57):
data[i] = chr(char).lower() + data[i][2:]
else:
if i > 0:
data[i] = '%' + data[i][:2].upper() + data[i][2:]
except:
if i > 0:
data[i] = '%' + data[i][:2].upper() + data[i][2:]
url = ''.join(data)
ret = []
i = 0
while i < len(url):
if i+2 < len(url) and url[i:i+3] == '/..':
while(ret.pop(-1) != '/'):
pass
i += 3
elif i+1 < len(url) and url[i:i+2] == '/.':
i += 2
else:
ret.append(url[i])
i += 1
url = ''.join(ret)
return url
checkio("http://Example.com:80/%48%6f%6d%45")
checkio("http://example.com:80/HOME/../././Guest/1/../2/..")
if __name__ == '__main__':
assert checkio(u"Http://Www.Checkio.org") == \
"http://www.checkio.org", "1st rule"
assert checkio(u"http://www.checkio.org/%cc%b1bac") ==\
"http://www.checkio.org/%CC%B1bac", "2nd rule"
assert checkio(u"http://www.checkio.org/task%5F%31") == \
"http://www.checkio.org/task_1", "3rd rule"
assert checkio(u"http://www.checkio.org:80/home/") == \
"http://www.checkio.org/home/", "4th rule"
assert checkio(u"http://www.checkio.org:8080/home/") == \
"http://www.checkio.org:8080/home/", "4th rule again"
assert checkio(u"http://www.checkio.org/task/./1/../2/././name") == \
"http://www.checkio.org/task/2/name", "5th rule"
print('First set of tests done')
第一名的代码，涵盖规则更多也更清楚
def checkio(url):
# 1. parse url
# 1.1. detach scheme
if ':' in url.split('/', 1)[0]:
scheme, url = url.split(':', 1)
else:
scheme = ''
# 1.2. detach fragment
if '#' in url:
url, fragment = url.rsplit('#', 1)
else:
fragment = ''
# 1.3. detach query
if '?' in url:
url, query = url.rsplit('?', 1)
else:
query = ''
# 1.4. detach authority
if url.startswith('//'):
url = url[2:]
if '/' in url:
authority, path = url.split('/', 1)
path = '/' + path
else:
authority, path = url, ''
else:
authority, path = '', url
# 1.5. detach userinfo
if '@' in authority:
userinfo, authority = authority.split('@', 1)
else:
userinfo = ''
# 1.6. split host and port
if ':' in authority:
host, port = authority.split(':', 1)
else:
host, port = authority, ''
# 1.7. split path segments
segments = path.split('/')
# 2. perform normalization
# 2.1. convert scheme and host to lowercase
scheme = scheme.lower()
host = host.lower()
# 2.1a. path segments should NOT be lowercased according to RFC 3986
# section 6.2.2.1. but the evaluator requires me to do that :S
segments = [s.lower() for s in segments]
# 2.2. process percent-encoded octets in userinfo, host and path segments
hexdigits = '0123456789ABCDEFabcdef'
alnum = ''.join(chr(i) for i in range(128) if chr(i).isalnum())
unreserved = alnum + '-._~'
# we associate a boolean to each escapable url part that tells whether we
# would like to lowercase unescaped characters (see also comment 2.1a.)
escapable = [(userinfo, False), (host, True)] + [(s, True) for s in segments]
processed = []
for s, lc in escapable:
t = s.split('%')
for i in range(1, len(t)):
# t[:2] is a possible percent-encoded octet (without the %)
if t[i][0] in hexdigits and t[i][1] in hexdigits:
c = chr(int(t[i][:2], 16))
if c in unreserved:
t[i] = (c.lower() if lc else c) + t[i][2:]
else:
t[i] = '%' + t[i][:2].upper() + t[i][2:]
else:
t[i] = '%' + t[i] # invalid percent encoding, ignore it
processed.append(''.join(t))
userinfo, host, *segments = processed
# 2.3. remove default port
defports = {
'ftp': 21, 'gopher': 70, 'http': 80, 'https': 443, 'ldap': 389,
'ldaps': 636, 'mms': 1755, 'news': 119, 'pop': 110, 'rlogin': 513,
'rsync': 873, 'rtsp': 554, 'rtspu': 554, 'sip': 5060, 'sips': 5061,
'snews': 563, 'ssh': 22, 'telnet': 23, 'tn3270': 23
}
if scheme in defports and port == str(defports[scheme]):
port = ''
# 2.4. remove dot-segments
processed = []
for s in segments:
if s == '.':
pass
elif s == '..':
processed and processed.pop() # remove last segment if it exists
else:
processed.append(s)
segments = processed
# 3. recompose url
# 3.1. join path
path = '/'.join(segments)
# 3.2. reconstruct authority
authority = host
if port:
authority += ':' + port
if userinfo:
authority = userinfo + authority
# 3.3. build complete url
url = ''
if scheme:
url += scheme + ':'
if authority:
url += '//' + authority
url += path
if query:
url += '?' + query
if fragment:
url += '#' + fragment
return url