# html.py - parser functions for html content
#
# Copyright (C) 2005, 2006 Arthur de Jong
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#
# The files produced as output from the software do not automatically fall
# under the copyright of the software, unless explicitly stated otherwise.
"""Parser functions for processing HTML content."""
import debugio
import HTMLParser
import urlparse
import re
import crawler
import htmlentitydefs
# the list of mimetypes this module should be able to handle
mimetypes = ('text/html', 'application/xhtml+xml', 'text/x-server-parsed-html')
# pattern for matching numeric html entities
_charentitypattern = re.compile('&#([0-9]{1,3});')
# pattern for matching all html entities
_entitypattern = re.compile('&(#[0-9]{1,6}|[a-zA-Z]{2,10});')
# pattern for matching spaces
_spacepattern = re.compile(' ')
# pattern for matching charset declaration for http-equiv tag
_charsetpattern = re.compile('charset=([^ ]*)', re.I)
# pattern for matching the encoding part of an xml declaration
_encodingpattern = re.compile('^xml .*encoding="([^"]*)"', re.I)
def htmlescape(txt, inattr=False):
"""HTML escape the given string and return an ASCII clean string with
known entities and character entities for the other values.
If the inattr parameter is set quotes and newlines will also be escaped."""
# convert to unicode object
if type(txt) is str:
txt = unicode(txt, errors='replace')
# the output string
out = ''
# loop over the characters of the string
for c in txt:
if c == '"':
if inattr:
out += '&%s;' % htmlentitydefs.codepoint2name[ord(c)]
else:
out += '"'
elif htmlentitydefs.codepoint2name.has_key(ord(c)):
out += '&%s;' % htmlentitydefs.codepoint2name[ord(c)]
elif ord(c) > 126:
out += '&#%d;'% ord(c)
elif inattr and c == u'\n':
out += ' '
else:
out += c.encode('utf-8')
return out
def _unescape_entity(match):
"""Helper function for htmlunescape().
This funcion unescapes a html entity, it is passed to the sub()
function."""
if htmlentitydefs.name2codepoint.has_key(match.group(1)):
# we have a named entity, return proper character
return unichr(htmlentitydefs.name2codepoint[match.group(1)])
elif match.group(1)[0] == '#':
# we have a numeric entity, replace with proper character
return unichr(int(match.group(1)[1:]))
else:
# we have something else, just keep the original
return match.group(0)
def htmlunescape(txt):
"""This function unescapes a html encoded string.
This function returns a unicode string."""
# convert to unicode
if type(txt) is str:
txt = unicode(txt, errors='replace')
# replace &name; and &#nn; refs with proper characters
txt = _entitypattern.sub(_unescape_entity, txt)
# we're done
return txt
class _MyHTMLParser(HTMLParser.HTMLParser):
"""A simple subclass of HTMLParser.HTMLParser continuing after errors
and gathering some information from the parsed content."""
def __init__(self, link):
"""Inialize the menbers in which we collect data from parsing the
document."""
self.link = link
self.collect = None
self.base = None
self.title = None
self.author = None
self.embedded = []
self.children = []
self.anchors = []
self.errmsg = None
self.errcount = 0
HTMLParser.HTMLParser.__init__(self)
def _location(self):
"""Return the current parser location as a string."""
(lineno, offset) = self.getpos()
if lineno is not None:
msg = 'at line %d' % lineno
else:
msg = 'at unknown line'
if offset is not None:
msg += ', column %d' % (offset + 1)
return msg
def _cleanurl(self, url, what='link'):
"""Do some translations of url."""
# check for spaces in urls
# (characters are escaped in crawler.urlescape())
if _spacepattern.search(url):
self.link.add_pageproblem(
what+' contains unescaped spaces: '+url+', '+self._location() )
# replace &#nnn; entity refs with proper characters
url = _charentitypattern.sub(lambda x:chr(int(x.group(1))), url)
return crawler.urlescape(url)
def error(self, message):
"""Override superclass' error() method to ignore errors."""
# construct error message
message += ', ' + self._location()
# store error message
debugio.debug('parsers.html._MyHTMLParser.error(): problem parsing html: '+message)
if self.errmsg is None:
self.errmsg = message
# increment error count
self.errcount += 1
if self.errcount > 10:
raise HTMLParser.HTMLParseError(message, self.getpos())
def check_for_whole_start_tag(self, i):
"""Override to catch assertion exception."""
try:
return HTMLParser.HTMLParser.check_for_whole_start_tag(self, i)
except AssertionError:
debugio.debug('parsers.html._MyHTMLParser.check_for_whole_start_tag(): caught assertion error')
return None
def handle_starttag(self, tag, attrs):
"""Handle start tags in html."""
# turn attrs into hash
attrs = dict(attrs)
# <title>TITLE</title>
if tag == 'title':
self.collect = ''
# <base href="URL">
elif tag == 'base' and attrs.has_key('href'):
self.base = self._cleanurl(attrs['href'])
# <link rel="type" href="URL">
elif tag == 'link' and attrs.has_key('rel') and attrs.has_key('href'):
if attrs['rel'].lower() in ('stylesheet', 'alternate stylesheet', 'icon', 'shortcut icon'):
self.embedded.append(self._cleanurl(attrs['href']))
# <meta name="author" content="AUTHOR">
elif tag == 'meta' and attrs.has_key('name') and attrs.has_key('content') and attrs['name'].lower() == 'author':
if self.author is None:
self.author = attrs['content']
# <meta http-equiv="refresh" content="0;url=URL">
elif tag == 'meta' and attrs.has_key('http-equiv') and attrs.has_key('content') and attrs['http-equiv'].lower() == 'refresh':
pass # TODO: implement
# <meta http-equiv="content-type" content="text/html; charset=utf-8" />
elif tag == 'meta' and attrs.has_key('http-equiv') and attrs.has_key('content') and attrs['http-equiv'].lower() == 'content-type':
if self.link.encoding is None:
try:
self.link.encoding = _charsetpattern.search(attrs['content']).group(1)
except AttributeError:
# ignore cases where encoding is not set in header
pass
# <img src="url">
elif tag == 'img' and attrs.has_key('src'):
self.embedded.append(self._cleanurl(attrs['src']))
# <a href="url" name="anchor" id="anchor">
elif tag == 'a':
# <a href="url">
if attrs.has_key('href'):
self.children.append(self._cleanurl(attrs['href']))
# <a name="anchor">
a_name = None
if attrs.has_key('name'):
a_name = self._cleanurl(attrs['name'], 'anchor')
# <a id="anchor">
a_id = None
if attrs.has_key('id'):
a_id = self._cleanurl(attrs['id'], 'anchor')
# if both id and name are used they should be the same
if a_id and a_name and a_id != a_name:
# add problem
self.link.add_pageproblem(
'anchors defined in name and id attributes do not match %(location)s'
% { 'location': self._location() })
elif a_id == a_name:
# ignore id if it's the same as name
a_id = None
# <a name="anchor">
if a_name:
if a_name in self.anchors:
self.link.add_pageproblem(
'anchor "%(anchor)s" defined again %(location)s'
% { 'anchor': a_name,
'location': self._location() })
else:
self.anchors.append(a_name)
# <a id="anchor">
if a_id:
if a_id in self.anchors:
self.link.add_pageproblem(
'anchor "%(anchor)s" defined again %(location)s'
% { 'anchor': a_id,
'location': self._location() })
else:
self.anchors.append(a_id)
# <frameset><frame src="url"...>...</frameset>
elif tag == 'frame' and attrs.has_key('src'):
self.embedded.append(self._cleanurl(attrs['src']))
# <map><area href="url"...>...</map>
elif tag == 'area' and attrs.has_key('href'):
self.children.append(self._cleanurl(attrs['href']))
# <applet code="url"...>
elif tag == 'applet' and attrs.has_key('code'):
self.embedded.append(self._cleanurl(attrs['code']))
# <embed src="url"...>
elif tag == 'embed' and attrs.has_key('src'):
self.embedded.append(self._cleanurl(attrs['src']))
# <embed><param name="movie" value="url"></embed>
elif tag == 'param' and attrs.has_key('name') and attrs.has_key('value'):
if attrs['name'].lower() == 'movie':
self.embedded.append(self._cleanurl(attrs['value']))
# <style>content</style>
elif tag == 'style':
self.collect = ''
def handle_endtag(self, tag):
"""Handle end tags in html."""
if tag == 'title' and self.title is None:
self.title = self.collect
self.collect = None
elif tag == 'style' and self.collect is not None:
# delegate handling of inline css to css module
import parsers.css
parsers.css.parse(self.collect, self.link)
def handle_data(self, data):
"""Collect data if we were collecting data."""
if self.collect is not None:
self.collect += data
def handle_charref(self, name):
"""Handle character references (e.g. A) by passing the data to
handle_data()."""
self.handle_data('&#'+name+';')
def handle_entityref(self, name):
"""Handle entity references (e.g. é) by passing the data to
handle_data()."""
self.handle_data('&'+name+';')
def handle_pi(self, data):
"""Hanlde xml declaration."""
# find character encoding from declaration
if self.link.encoding is None:
try:
self.link.encoding = _encodingpattern.search(data).group(1)
except AttributeError:
pass
def _maketxt(txt, encoding):
"""Return an unicode text of the specified string do correct character
conversions and replacing html entities with normal characters."""
# try to decode with the given encoding
if encoding:
try:
return htmlunescape(unicode(txt, encoding, 'replace'))
except (LookupError, TypeError), e:
debugio.warn('page has unknown encoding: %s' % str(encoding))
# fall back to locale's encoding
return htmlunescape(unicode(txt, errors='replace'))
def parse(content, link):
"""Parse the specified content and extract an url list, a list of images a
title and an author. The content is assumed to contain HMTL."""
# create parser and feed it the content
parser = _MyHTMLParser(link)
try:
parser.feed(content)
parser.close()
except Exception, e:
# ignore (but log) all errors
debugio.debug('parsers.html.parse(): caught exception: '+str(e))
# check for parser errors
if parser.errmsg is not None:
debugio.debug('parsers.html.parse(): problem parsing html: '+parser.errmsg)
link.add_pageproblem('problem parsing html: %s' % parser.errmsg)
# dump encoding
debugio.debug('parsers.html.parse(): html encoding: %s' % str(link.encoding))
# flag that the link contains a valid page
link.ispage = True
# save the title
if parser.title is not None:
link.title = _maketxt(parser.title, link.encoding).strip()
# save the author
if parser.author is not None:
link.author = _maketxt(parser.author, link.encoding).strip()
# figure out the base of the document (for building the other urls)
base = link.url
if parser.base is not None:
base = parser.base
# list embedded and children
for embed in parser.embedded:
if embed:
link.add_embed(urlparse.urljoin(base, embed))
for child in parser.children:
if child:
link.add_child(urlparse.urljoin(base, child))
# list anchors
for anchor in parser.anchors:
if anchor:
link.add_anchor(anchor)