mirror of https://github.com/python/cpython
Skip Montanaro's robots.txt parser.
This commit is contained in:
Guido van Rossum
parent
272b37d686
commit
bbf8c2fafd
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"""
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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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"""
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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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self.last_checked = 0
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def mtime(self):
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return self.last_checked
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def modified(self):
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import time
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self.last_checked = time.time()
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def set_url(self, url):
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self.url = url
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## import urlmisc
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## self.url = urlmisc.canonical_url(url)
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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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def parse(self, lines):
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import regsub, string, regex
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active = []
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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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# remove optional comment and strip line
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line = string.strip(line[:string.find(line, '#')])
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if not line:
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continue
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line = regsub.split(line, ' *: *')
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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(regex.compile(line[1]))
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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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else:
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if self.debug: print '>> unknown:', line
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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, agent, url):
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import urlparse
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ag = agent
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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', agent
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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) != -1:
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if self.debug: print '>> disallowing', url, 'fetch by', agent
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return 0
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if self.debug: print '>> allowing', url, 'fetch by', agent
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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.automatrix.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.calendar.com/concerts/')
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print rp.can_fetch('Musi-Cal-Robot',
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'http://dolphin:80/cgi-bin/music-search?performer=Rolling+Stones')
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print rp.can_fetch('Lycos', 'http://www/~skip/volkswagen/')
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print rp.can_fetch('Lycos', 'http://www/~skip/volkswagen/vanagon-list-001')
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@ -0,0 +1,97 @@
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"""
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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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"""
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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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self.last_checked = 0
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def mtime(self):
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return self.last_checked
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def modified(self):
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import time
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self.last_checked = time.time()
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def set_url(self, url):
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self.url = url
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## import urlmisc
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## self.url = urlmisc.canonical_url(url)
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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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def parse(self, lines):
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import regsub, string, regex
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active = []
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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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# remove optional comment and strip line
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line = string.strip(line[:string.find(line, '#')])
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if not line:
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continue
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line = regsub.split(line, ' *: *')
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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(regex.compile(line[1]))
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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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else:
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if self.debug: print '>> unknown:', line
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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, agent, url):
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import urlparse
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ag = agent
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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', agent
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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) != -1:
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if self.debug: print '>> disallowing', url, 'fetch by', agent
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return 0
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if self.debug: print '>> allowing', url, 'fetch by', agent
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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.automatrix.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.calendar.com/concerts/')
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print rp.can_fetch('Musi-Cal-Robot',
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'http://dolphin:80/cgi-bin/music-search?performer=Rolling+Stones')
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print rp.can_fetch('Lycos', 'http://www/~skip/volkswagen/')
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print rp.can_fetch('Lycos', 'http://www/~skip/volkswagen/vanagon-list-001')
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