[whatwg] Allowing ">" in attribute values

Fri Jun 25 02:46:12 PDT 2010

On 24 Jun 2010, at 14:11, Benjamin M. Schwartz wrote:

>>> Why would it simplify parsing?

>> It greatly simplifies parsing when you just want to extract entire 
>> tags, without immediately parsing the attributes.

>If you mean "parsing" with regular expressions, then I think that's a bad
practice and shouldn't be encouraged. 

A agree disallowing ">" chars in attributes greatly simplifies parsing. Not
only with regular expressions, but any parsing.
If ">" are allowed, it means that in order to found the end of the element
you do have to read all attributes before. This is very costy. Just an
example but they are many others:  let's image you'd like to convert an HTML
document into flat text. To simplify you're algorithm you've chosen  to
retrieve the content of the <body> element and then to delete all elements
in it. This is very fast if ">" are not allowed in attributes because you're
able found elements bounds just by searching "<" and then ">".  But if ">"
are allowed, the operation gets much more complicated, and you spend much
more time to scan all elements.

In my opinion, the gain of allowing ">" is so poor regarding to the troubles
it makes, that it should be forbidden in both XML and HTML (any version).

> Also take into consideration that even if ">" was forbidden in the 
> spec, it wouldn't mean it doesn't happen in the wild. Since it works in
browsers, you'd still have to support it if you wanted to parse markup from
the web.

Allowing it in the spec and how the browser should  behave if it is anyway
are two different things.

Regards,
Skrol29