"urllib.robotparser" —  Parser for robots.txt
*********************************************

**Source code:** Lib/urllib/robotparser.py

======================================================================

This module provides a single class, "RobotFileParser", which answers
questions about whether or not a particular user agent can fetch a URL
on the web site that published the "robots.txt" file.  For more
details on the structure of "robots.txt" files, see
http://www.robotstxt.org/orig.html.

class urllib.robotparser.RobotFileParser(url='')

   This class provides methods to read, parse and answer questions
   about the "robots.txt" file at *url*.

   set_url(url)

      Sets the URL referring to a "robots.txt" file.

   read()

      Reads the "robots.txt" URL and feeds it to the parser.

   parse(lines)

      Parses the lines argument.

   can_fetch(useragent, url)

      Returns "True" if the *useragent* is allowed to fetch the *url*
      according to the rules contained in the parsed "robots.txt"
      file.

   mtime()

      Returns the time the "robots.txt" file was last fetched.  This
      is useful for long-running web spiders that need to check for
      new "robots.txt" files periodically.

   modified()

      Sets the time the "robots.txt" file was last fetched to the
      current time.

   crawl_delay(useragent)

      Returns the value of the "Crawl-delay" parameter from
      "robots.txt" for the *useragent* in question.  If there is no
      such parameter or it doesn’t apply to the *useragent* specified
      or the "robots.txt" entry for this parameter has invalid syntax,
      return "None".

      New in version 3.6.

   request_rate(useragent)

      Returns the contents of the "Request-rate" parameter from
      "robots.txt" as a *named tuple* "RequestRate(requests,
      seconds)". If there is no such parameter or it doesn’t apply to
      the *useragent* specified or the "robots.txt" entry for this
      parameter has invalid syntax, return "None".

      New in version 3.6.

   site_maps()

      Returns the contents of the "Sitemap" parameter from
      "robots.txt" in the form of a "list()". If there is no such
      parameter or the "robots.txt" entry for this parameter has
      invalid syntax, return "None".

      New in version 3.8.

The following example demonstrates basic use of the "RobotFileParser"
class:

   >>> import urllib.robotparser
   >>> rp = urllib.robotparser.RobotFileParser()
   >>> rp.set_url("http://www.musi-cal.com/robots.txt")
   >>> rp.read()
   >>> rrate = rp.request_rate("*")
   >>> rrate.requests
   3
   >>> rrate.seconds
   20
   >>> rp.crawl_delay("*")
   6
   >>> rp.can_fetch("*", "http://www.musi-cal.com/cgi-bin/search?city=San+Francisco")
   False
   >>> rp.can_fetch("*", "http://www.musi-cal.com/")
   True
