# html.py - parser functions for html content # # Copyright (C) 2005, 2006, 2007 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. This module uses the legacy HTMLParser module. It will only be used if BeatifulSoup is not available and can be considered depricated. This parser will only handle properly formatted HTML.""" import debugio import HTMLParser import urlparse import re import crawler import myurllib from parsers.html import htmlunescape # pattern for matching numeric html entities _charentitypattern = re.compile('&#([0-9]{1,3});') # 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) 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 myurllib.normalizeurl()) 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 myurllib.normalizeurl(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.htmlparser._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.htmlparser._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 if tag == 'title': self.collect = '' # elif tag == 'base' and attrs.has_key('href'): self.base = self._cleanurl(attrs['href']) # 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'])) # 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'] # elif tag == 'meta' and attrs.has_key('http-equiv') and attrs.has_key('content') and attrs['http-equiv'].lower() == 'refresh': pass # TODO: implement # elif tag == 'meta' and attrs.has_key('http-equiv') and attrs.has_key('content') and attrs['http-equiv'].lower() == 'content-type': try: self.link.set_encoding(_charsetpattern.search(attrs['content']).group(1)) except AttributeError: # ignore cases where encoding is not set in header pass # elif tag == 'img' and attrs.has_key('src'): self.embedded.append(self._cleanurl(attrs['src'])) # elif tag == 'a': # if attrs.has_key('href'): self.children.append(self._cleanurl(attrs['href'])) # a_name = None if attrs.has_key('name'): a_name = self._cleanurl(attrs['name'], '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 # 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) # 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) # ... elif tag == 'frame' and attrs.has_key('src'): self.embedded.append(self._cleanurl(attrs['src'])) # ... elif tag == 'area' and attrs.has_key('href'): self.children.append(self._cleanurl(attrs['href'])) # elif tag == 'applet' and attrs.has_key('archive'): self.embedded.append(self._cleanurl(attrs['archive'])) # elif tag == 'applet' and attrs.has_key('code'): self.embedded.append(self._cleanurl(attrs['code'])) # elif tag == 'embed' and attrs.has_key('src'): self.embedded.append(self._cleanurl(attrs['src'])) # 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'])) # 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+';') # TODO: do not pass ; if plain text does not contain it? def handle_entityref(self, name): """Handle entity references (e.g. é) by passing the data to handle_data().""" self.handle_data('&'+name+';') # TODO: do not pass ; if plain text does not contain it? def handle_pi(self, data): """Handle xml declaration.""" # find character encoding from declaration try: self.link.set_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, ValueError), 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.htmlparser.parse(): caught exception: '+str(e)) # check for parser errors if parser.errmsg is not None: debugio.debug('parsers.html.htmlparser.parse(): problem parsing html: '+parser.errmsg) link.add_pageproblem('problem parsing html: %s' % parser.errmsg) # dump encoding debugio.debug('parsers.html.htmlparser.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)