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"""
Offsite Spider Middleware
See documentation in docs/topics/spider-middleware.rst
"""
import re
from scrapy.xlib.pydispatch import dispatcher
from scrapy import signals
from scrapy.http import Request
from scrapy.utils.httpobj import urlparse_cached
from scrapy import log
class OffsiteMiddleware(object):
def __init__(self):
self.host_regexes = {}
self.domains_seen = {}
dispatcher.connect(self.spider_opened, signal=signals.spider_opened)
dispatcher.connect(self.spider_closed, signal=signals.spider_closed)
def process_spider_output(self, response, result, spider):
for x in result:
if isinstance(x, Request):
if x.dont_filter or self.should_follow(x, spider):
yield x
else:
domain = urlparse_cached(x).hostname
if domain and domain not in self.domains_seen[spider]:
log.msg("Filtered offsite request to %r: %s" % (domain, x),
level=log.DEBUG, spider=spider)
self.domains_seen[spider].add(domain)
else:
yield x
def should_follow(self, request, spider):
regex = self.host_regexes[spider]
# hostanme can be None for wrong urls (like javascript links)
host = urlparse_cached(request).hostname or ''
return bool(regex.search(host))
def get_host_regex(self, spider):
"""Override this method to implement a different offsite policy"""
allowed_domains = getattr(spider, 'allowed_domains', None)
if not allowed_domains:
return re.compile('') # allow all by default
domains = [d.replace('.', r'\.') for d in allowed_domains]
regex = r'^(.*\.)?(%s)$' % '|'.join(domains)
return re.compile(regex)
def spider_opened(self, spider):
self.host_regexes[spider] = self.get_host_regex(spider)
self.domains_seen[spider] = set()
def spider_closed(self, spider):
del self.host_regexes[spider]
del self.domains_seen[spider]
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