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eb3cf28baa
The LinkFinder handler start_end_element() callback does nothing apart from call start_element().
247 lines
8.9 KiB
Python
247 lines
8.9 KiB
Python
# -*- coding: iso-8859-1 -*-
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# Copyright (C) 2001-2014 Bastian Kleineidam
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program; if not, write to the Free Software Foundation, Inc.,
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# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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"""
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Find link tags in HTML text.
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"""
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import re
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from .. import strformat, log, LOG_CHECK, url as urlutil
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from builtins import str as str_text
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unquote = strformat.unquote
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# HTML4/5 link tags
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# ripped mainly from HTML::Tagset.pm with HTML5 added
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LinkTags = {
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'a': [u'href'],
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'applet': [u'archive', u'src'],
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'area': [u'href'],
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'audio': [u'src'], # HTML5
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'bgsound': [u'src'],
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'blockquote': [u'cite'],
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'body': [u'background'],
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'button': [u'formaction'], # HTML5
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'del': [u'cite'],
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'embed': [u'pluginspage', u'src'],
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'form': [u'action'],
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'frame': [u'src', u'longdesc'],
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'head': [u'profile'],
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'html': [u'manifest'], # HTML5
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'iframe': [u'src', u'longdesc'],
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'ilayer': [u'background'],
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'img': [u'src', u'lowsrc', u'longdesc', u'usemap', u'srcset'],
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'input': [u'src', u'usemap', u'formaction'],
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'ins': [u'cite'],
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'isindex': [u'action'],
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'layer': [u'background', u'src'],
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'link': [u'href'],
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'meta': [u'content', u'href'],
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'object': [u'classid', u'data', u'archive', u'usemap', u'codebase'],
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'q': [u'cite'],
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'script': [u'src'],
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'source': [u'src'], # HTML5
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'table': [u'background'],
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'td': [u'background'],
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'th': [u'background'],
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'tr': [u'background'],
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'track': [u'src'], # HTML5
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'video': [u'src'], # HTML5
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'xmp': [u'href'],
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None: [u'style', u'itemtype'],
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}
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# HTML anchor tags
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AnchorTags = {
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'a': [u'name'],
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None: [u'id'],
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}
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# WML tags
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WmlTags = {
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'a': [u'href'],
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'go': [u'href'],
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'img': [u'src'],
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}
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# matcher for <meta http-equiv=refresh> tags
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refresh_re = re.compile(r"(?i)^\d+;\s*url=(?P<url>.+)$")
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_quoted_pat = r"('[^']+'|\"[^\"]+\"|[^\)\s]+)"
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css_url_re = re.compile(r"url\(\s*(?P<url>%s)\s*\)" % _quoted_pat)
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swf_url_re = re.compile("(?i)%s" % urlutil.safe_url_pattern)
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c_comment_re = re.compile(r"/\*.*?\*/", re.DOTALL)
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def strip_c_comments (text):
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"""Remove C/CSS-style comments from text. Note that this method also
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deliberately removes comments inside of strings."""
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return c_comment_re.sub('', text)
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class StopParse(Exception):
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"""Raised when parsing should stop."""
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pass
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class TagFinder (object):
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"""Base class handling HTML start elements.
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TagFinder instances are used as HtmlParser handlers."""
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def __init__ (self):
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"""Initialize local variables."""
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super(TagFinder, self).__init__()
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def start_element (self, tag, attrs, element_text, lineno, column):
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"""Does nothing, override in a subclass."""
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pass
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class MetaRobotsFinder (TagFinder):
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"""Class for finding robots.txt meta values in HTML."""
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def __init__ (self):
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"""Initialize follow and index flags."""
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super(MetaRobotsFinder, self).__init__()
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log.debug(LOG_CHECK, "meta robots finder")
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self.follow = self.index = True
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def start_element (self, tag, attrs, element_text, lineno, column):
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"""Search for meta robots.txt "nofollow" and "noindex" flags."""
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if tag == 'meta' and attrs.get('name') == 'robots':
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val = attrs.get('content', u'').lower().split(u',')
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self.follow = u'nofollow' not in val
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self.index = u'noindex' not in val
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raise StopParse("found <meta name=robots> tag")
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elif tag == 'body':
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raise StopParse("found <body> tag")
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def is_meta_url (attr, attrs):
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"""Check if the meta attributes contain a URL."""
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res = False
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if attr == "content":
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equiv = attrs.get('http-equiv', u'').lower()
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scheme = attrs.get('scheme', u'').lower()
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res = equiv in (u'refresh',) or scheme in (u'dcterms.uri',)
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if attr == "href":
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rel = attrs.get('rel', u'').lower()
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res = rel in (u'shortcut icon', u'icon')
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return res
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def is_form_get(attr, attrs):
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"""Check if this is a GET form action URL."""
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res = False
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if attr == "action":
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method = attrs.get('method', u'').lower()
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res = method != 'post'
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return res
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class LinkFinder (TagFinder):
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"""Find HTML links, and apply them to the callback function with the
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format (url, lineno, column, name, codebase)."""
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def __init__ (self, callback, tags):
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"""Store content in buffer and initialize URL list."""
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super(LinkFinder, self).__init__()
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self.callback = callback
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# set universal tag attributes using tagname None
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self.universal_attrs = set(tags.get(None, []))
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self.tags = dict()
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for tag, attrs in tags.items():
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self.tags[tag] = set(attrs)
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# add universal tag attributes
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self.tags[tag].update(self.universal_attrs)
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self.base_ref = u''
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def start_element (self, tag, attrs, element_text, lineno, column):
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"""Search for links and store found URLs in a list."""
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log.debug(LOG_CHECK, "LinkFinder tag %s attrs %s", tag, attrs)
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log.debug(LOG_CHECK, "line %d col %d", lineno, column)
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if tag == "base" and not self.base_ref:
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self.base_ref = attrs.get("href", u'')
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tagattrs = self.tags.get(tag, self.universal_attrs)
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# parse URLs in tag (possibly multiple URLs in CSS styles)
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for attr in sorted(tagattrs.intersection(attrs)):
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if tag == "meta" and not is_meta_url(attr, attrs):
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continue
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if tag == "form" and not is_form_get(attr, attrs):
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continue
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# name of this link
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name = self.get_link_name(tag, attrs, attr, element_text)
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# possible codebase
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base = u''
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if tag == 'applet':
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base = attrs.get('codebase', u'')
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if not base:
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base = self.base_ref
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# note: value can be None
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value = attrs.get(attr)
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if tag == 'link' and attrs.get('rel') == 'dns-prefetch':
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if ':' in value:
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value = value.split(':', 1)[1]
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value = 'dns:' + value.rstrip('/')
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# parse tag for URLs
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self.parse_tag(tag, attr, value, name, base, lineno, column)
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log.debug(LOG_CHECK, "LinkFinder finished tag %s", tag)
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def get_link_name (self, tag, attrs, attr, name=None):
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"""Parse attrs for link name. Return name of link."""
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if tag == 'a' and attr == 'href':
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if not name:
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name = attrs.get('title', u'')
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elif tag == 'img':
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name = attrs.get('alt', u'')
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if not name:
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name = attrs.get('title', u'')
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else:
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name = u""
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return name
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def parse_tag (self, tag, attr, value, name, base, lineno, column):
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"""Add given url data to url list."""
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assert isinstance(tag, str_text), repr(tag)
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assert isinstance(attr, str_text), repr(attr)
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assert isinstance(name, str_text), repr(name)
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assert isinstance(base, str_text), repr(base)
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assert isinstance(value, str_text) or value is None, repr(value)
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# look for meta refresh
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if tag == u'meta' and value:
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mo = refresh_re.match(value)
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if mo:
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self.found_url(mo.group("url"), name, base, lineno, column)
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elif attr != 'content':
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self.found_url(value, name, base, lineno, column)
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elif attr == u'style' and value:
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for mo in css_url_re.finditer(value):
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url = unquote(mo.group("url"), matching=True)
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self.found_url(url, name, base, lineno, column)
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elif attr == u'archive':
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for url in value.split(u','):
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self.found_url(url, name, base, lineno, column)
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elif attr == u'srcset':
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for img_candidate in value.split(u','):
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url = img_candidate.split()[0]
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self.found_url(url, name, base, lineno, column)
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else:
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self.found_url(value, name, base, lineno, column)
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def found_url(self, url, name, base, lineno, column):
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"""Add newly found URL to queue."""
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assert isinstance(url, str_text) or url is None, repr(url)
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self.callback(url, line=lineno, column=column, name=name, base=base)
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