Python in a Nutshell

Name

handle_starttag

Synopsis

                     h.handle_starttag(tag, attributes)

Called to handle tags. tag is the tag string, lowercased. attributes is a list of pairs ( name,value ), where name is each attribute’s name, lowercased, and value is the value, processed to resolve entity references and character references and to remove surrounding quotes. HTMLParser’s implementation of handle_starttag does nothing.

The following example uses HTMLParser to perform the same task as our previous examples: fetching a page from the Web with urllib, parsing it, and outputting the hyperlinks.

import HTMLParser, urllib, urlparse

class LinksParser(HTMLParser.HTMLParser):
    def __init_  _(self):
        HTMLParser.HTMLParser.__init_  _(self)
        self.seen = {}
    def handle_starttag(self, tag, attributes):
        if tag != 'a': return
        for name, value in attributes:
            if name == 'href' and value not in self.seen:
                self.seen[value] = True
                pieces = urlparse.urlparse(value)
                if pieces[0] != 'http': return
                print urlparse.urlunparse(pieces)
                return

p = LinksParser( )
f = urllib.urlopen('http://www.python.org/index.html')
BUFSIZE = 8192
while True:
    data = f.read(BUFSIZE)
    if not data: break
    p.feed(data)

p.close( )

This example is similar to the one for sgmllib. However, since the HTMLParser.HTMLParser superclass performs no per-tag dispatching to methods, class LinksParser needs to override method handle_starttag and check that the tag is indeed 'a‘.