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rewrite of robotparser.py by Bastian Kleineidam. Closes patch 102229.
This commit is contained in:
Skip Montanaro
parent
a5d23a19e6
commit
663f6c2ad2
1 changed files with 180 additions and 61 deletions
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@ -1,17 +1,28 @@
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"""
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""" robotparser.py
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Robots.txt file parser class. Accepts a list of lines or robots.txt URL as
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input, builds a set of rules from that list, then answers questions about
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fetchability of other URLs.
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Copyright (C) 2000 Bastian Kleineidam
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You can choose between two licenses when using this package:
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1) GNU GPLv2
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2) PYTHON 2.0 OPEN SOURCE LICENSE
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The robots.txt Exclusion Protocol is implemented as specified in
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http://info.webcrawler.com/mak/projects/robots/norobots-rfc.html
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"""
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import re,string,urlparse,urllib
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debug = 0
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def _debug(msg):
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if debug: print msg
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class RobotFileParser:
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def __init__(self):
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self.rules = {}
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self.debug = 0
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self.url = ''
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def __init__(self, url=''):
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self.entries = []
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self.disallow_all = 0
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self.allow_all = 0
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self.set_url(url)
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self.last_checked = 0
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def mtime(self):
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@ -23,75 +34,183 @@ class RobotFileParser:
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def set_url(self, url):
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self.url = url
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self.host, self.path = urlparse.urlparse(url)[1:3]
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def read(self):
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import urllib
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self.parse(urllib.urlopen(self.url).readlines())
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import httplib
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tries = 0
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while tries<5:
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connection = httplib.HTTP(self.host)
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connection.putrequest("GET", self.path)
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connection.putheader("Host", self.host)
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connection.endheaders()
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status, text, mime = connection.getreply()
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if status in [301,302] and mime:
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tries = tries + 1
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newurl = mime.get("Location", mime.get("Uri", ""))
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newurl = urlparse.urljoin(self.url, newurl)
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self.set_url(newurl)
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else:
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break
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if status==401 or status==403:
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self.disallow_all = 1
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elif status>=400:
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self.allow_all = 1
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else:
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# status < 400
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self.parse(connection.getfile().readlines())
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def parse(self, lines):
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"""parse the input lines from a robot.txt file"""
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import string, re
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active = []
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"""parse the input lines from a robot.txt file.
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We allow that a user-agent: line is not preceded by
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one or more blank lines."""
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state = 0
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linenumber = 0
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entry = Entry()
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for line in lines:
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if self.debug: print '>', line,
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# blank line terminates current record
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if not line[:-1]:
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active = []
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continue
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line = string.strip(line)
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linenumber = linenumber + 1
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if not line:
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if state==1:
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_debug("line %d: warning: you should insert"
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" allow: or disallow: directives below any"
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" user-agent: line" % linenumber)
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entry = Entry()
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state = 0
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elif state==2:
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self.entries.append(entry)
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entry = Entry()
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state = 0
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# remove optional comment and strip line
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line = string.strip(line[:string.find(line, '#')])
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i = string.find(line, '#')
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if i>=0:
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line = line[:i]
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line = string.strip(line)
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if not line:
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continue
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line = re.split(' *: *', line)
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line = string.split(line, ':', 1)
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if len(line) == 2:
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line[0] = string.lower(line[0])
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if line[0] == 'user-agent':
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# this record applies to this user agent
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if self.debug: print '>> user-agent:', line[1]
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active.append(line[1])
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if not self.rules.has_key(line[1]):
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self.rules[line[1]] = []
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elif line[0] == 'disallow':
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if line[1]:
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if self.debug: print '>> disallow:', line[1]
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for agent in active:
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self.rules[agent].append(re.compile(line[1]))
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line[0] = string.lower(string.strip(line[0]))
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line[1] = string.strip(line[1])
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if line[0] == "user-agent":
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if state==2:
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_debug("line %d: warning: you should insert a blank"
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" line before any user-agent"
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" directive" % linenumber)
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self.entries.append(entry)
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entry = Entry()
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entry.useragents.append(line[1])
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state = 1
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elif line[0] == "disallow":
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if state==0:
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_debug("line %d: error: you must insert a user-agent:"
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" directive before this line" % linenumber)
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else:
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pass
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for agent in active:
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if self.debug: print '>> allow', agent
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self.rules[agent] = []
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entry.rulelines.append(RuleLine(line[1], 0))
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state = 2
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elif line[0] == "allow":
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if state==0:
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_debug("line %d: error: you must insert a user-agent:"
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" directive before this line" % linenumber)
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else:
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entry.rulelines.append(RuleLine(line[1], 1))
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else:
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if self.debug: print '>> unknown:', line
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_debug("line %d: warning: unknown key %s" % (linenumber,
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line[0]))
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else:
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_debug("line %d: error: malformed line %s"%(linenumber, line))
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if state==2:
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self.entries.append(entry)
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_debug("Parsed rules:\n%s" % str(self))
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self.modified()
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# returns true if agent is allowed to fetch url
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def can_fetch(self, useragent, url):
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"""using the parsed robots.txt decide if useragent can fetch url"""
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import urlparse
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ag = useragent
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if not self.rules.has_key(ag): ag = '*'
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if not self.rules.has_key(ag):
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if self.debug: print '>> allowing', url, 'fetch by', useragent
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_debug("Checking robot.txt allowance for\n%s\n%s" % (useragent, url))
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if self.disallow_all:
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return 0
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if self.allow_all:
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return 1
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path = urlparse.urlparse(url)[2]
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for rule in self.rules[ag]:
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if rule.match(path) is not None:
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if self.debug: print '>> disallowing', url, 'fetch by', useragent
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return 0
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if self.debug: print '>> allowing', url, 'fetch by', useragent
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# search for given user agent matches
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# the first match counts
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useragent = string.lower(useragent)
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url = urllib.quote(urlparse.urlparse(url)[2])
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for entry in self.entries:
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if entry.applies_to(useragent):
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return entry.allowance(url)
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# agent not found ==> access granted
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return 1
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def _test():
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rp = RobotFileParser()
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rp.debug = 1
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rp.set_url('http://www.musi-cal.com/robots.txt')
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rp.read()
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print rp.rules
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print rp.can_fetch('*', 'http://www.musi-cal.com.com/')
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print rp.can_fetch('Musi-Cal-Robot',
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'http://www.musi-cal.com/cgi-bin/event-search?city=San+Francisco')
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if __name__ == "__main__":
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def __str__(self):
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ret = ""
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for entry in self.entries:
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ret = ret + str(entry) + "\n"
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return ret
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class RuleLine:
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"""A rule line is a single "Allow:" (allowance==1) or "Disallow:"
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(allowance==0) followed by a path."""
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def __init__(self, path, allowance):
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self.path = urllib.quote(path)
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self.allowance = allowance
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def applies_to(self, filename):
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return self.path=="*" or re.match(self.path, filename)
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def __str__(self):
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return (self.allowance and "Allow" or "Disallow")+": "+self.path
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class Entry:
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"""An entry has one or more user-agents and zero or more rulelines"""
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def __init__(self):
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self.useragents = []
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self.rulelines = []
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def __str__(self):
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ret = ""
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for agent in self.useragents:
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ret = ret + "User-agent: "+agent+"\n"
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for line in self.rulelines:
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ret = ret + str(line) + "\n"
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return ret
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def applies_to(self, useragent):
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"check if this entry applies to the specified agent"
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for agent in self.useragents:
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if agent=="*":
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return 1
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if re.match(agent, useragent):
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return 1
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return 0
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def allowance(self, filename):
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"""Preconditions:
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- our agent applies to this entry
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- filename is URL decoded"""
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for line in self.rulelines:
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if line.applies_to(filename):
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return line.allowance
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return 1
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def _test():
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global debug
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import sys
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rp = RobotFileParser()
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debug = 1
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if len(sys.argv) <= 1:
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rp.set_url('http://www.musi-cal.com/robots.txt')
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rp.read()
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else:
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rp.parse(open(sys.argv[1]).readlines())
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print rp.can_fetch('*', 'http://www.musi-cal.com/')
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print rp.can_fetch('Musi-Cal-Robot/1.0',
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'http://www.musi-cal.com/cgi-bin/event-search'
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'?city=San+Francisco')
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if __name__ == '__main__':
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_test()
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