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HTMLParser chokes on bad end tag in comment

Rene Pijlman
P: n/a
Rene Pijlman
The code below results in an exception (Python 2.4.2):

HTMLParser.HTMLParseError: bad end tag: "</foo' + 'bar>", at line 4,
column 6

Should it? The end tag it chokes on is in comment, isn't it?

import HTMLParser
HTMLParser.HTMLParser().feed("""
<html><head><title></title></head><body><script>
<!--
x = '</foo' + 'bar>'
// -->
</script></body></html>
""")

--
René Pijlman
May 28 '06 #1
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6 Replies


Fredrik Lundh
P: n/a
Fredrik Lundh
Rene Pijlman wrote:
[color=blue]
> The code below results in an exception (Python 2.4.2):
>
> HTMLParser.HTMLParseError: bad end tag: "</foo' + 'bar>", at line 4,
> column 6
>
> Should it? The end tag it chokes on is in comment, isn't it?[/color]

no. STYLE and SCRIPT elements contain character data, not parsed
character data, so comments are treated as characters, and the first
"</" ends the element.

if you have broken documents, you can tweak this by setting the
CDATA_CONTENT_ELEMENTS parser attribute before you start parsing.

</F>

May 29 '06 #2

Rene Pijlman
P: n/a
Rene Pijlman
Fredrik Lundh:[color=blue]
>Rene Pijlman:
>[end tag in html comment in script element]
>The end tag it chokes on is in comment, isn't it?
>
>no. STYLE and SCRIPT elements contain character data, not parsed
>character data, so comments are treated as characters, and the first
>"</" ends the element.[/color]

Ah, I see. I'll report the problem to the application that's generating
this broken code (vBulletin forum)...
[color=blue]
>if you have broken documents, you can tweak this by setting the
>CDATA_CONTENT_ELEMENTS parser attribute before you start parsing.[/color]

.... and in the mean time that's a good workaround.

Thank you very much Fredrik.

--
René Pijlman
May 29 '06 #3

Miki
P: n/a
Miki
Hello Rene,

You can also check out BeautifulSoup
(http://www.crummy.com/software/BeautifulSoup/) which is less strict
than the regular HTML parser.

HTH,
Miki
http://pythonwise.blogspot.com/

May 29 '06 #4

Rene Pijlman
P: n/a
Rene Pijlman
Miki:[color=blue]
>You can also check out BeautifulSoup
>(http://www.crummy.com/software/BeautifulSoup/) which is less strict
>than the regular HTML parser.[/color]

Yes, thanks. Ik this case it was my sitechecker which checks for syntax
and broken links, so it was supposed to find the syntax error.
BeautifulSoup is not very well suited for validators :-)

--
René Pijlman
May 29 '06 #5

Edward Elliott
P: n/a
Edward Elliott
Fredrik Lundh wrote:
[color=blue][color=green]
>> Should it? The end tag it chokes on is in comment, isn't it?[/color]
>
> no. STYLE and SCRIPT elements contain character data, not parsed
> character data, so comments are treated as characters, and the first
> "</" ends the element.[/color]

Rather than take your word for it, I checked the W3C HTML4 DTD and found
this:

http://www.w3.org/TR/html4/appendix/...pecifying-data

Element content

When script or style data is the content of an element (SCRIPT and STYLE),
the data begins immediately after the element start tag and ends at the
first ETAGO ("</") delimiter followed by a name start character ([a-zA-Z]);
note that this may not be the element's end tag. Authors should therefore
escape "</" within the content. Escape mechanisms are specific to each
scripting or style sheet language.

ILLEGAL EXAMPLE:
The following script data incorrectly contains a "</" sequence (as part of
"</EM>") before the SCRIPT end tag:

<SCRIPT type="text/javascript">
document.write ("<EM>This won't work</EM>")
</SCRIPT>

In JavaScript, this code can be expressed legally by hiding the ETAGO
delimiter before an SGML name start character:

<SCRIPT type="text/javascript">
document.write ("<EM>This will work<\/EM>")
</SCRIPT>


Guess you learn something new every day. Too bad there's so much illegal
code in the wild. :(

--
Edward Elliott
UC Berkeley School of Law (Boalt Hall)
complangpython at eddeye dot net
May 29 '06 #6

Fredrik Lundh
P: n/a
Fredrik Lundh
Edward Elliott wrote:
[color=blue]
> Guess you learn something new every day. Too bad there's so much illegal
> code in the wild. :([/color]

if more people learned something new every day, the wild would look a
lot different.

</F>


May 29 '06 #7

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