<DIV> </DIV><PRE>2009-07-20，"Stefan Behnel" <stefan_ml@behnel.de> ：
>
>Nicholas Dudfield wrote:
>> Wow, someone else with this requirement. I was meaning to post to the
>> list about this. I'm using lxml to implement a XPath / CSS selection
>> plugin for a python extensible editor. I'd like to have a mapping of
>> view buffer regions to xml nodes.
>
>At least the line is available from the "sourceline" property of an element
>- although only up to 65536:
>
>http://bugzilla.gnome.org/show_bug.cgi?id=325533
>
>If you are in a position to whitespace-clean and pretty-print the XML
>document, that would give you a simple mapping from elements to document
>positions that you can exploit at the application level. Even if you can't,
>that would still give you a usable model to work with that you could match
>with the original stream to find the 'real' positions.
>
>
>> The workaround I used to get the
>> exact character position was to use the feed interface, a character at
>> a time and manually monitor bytestream position. It's fairly slow
>> though. I'd like to implement this in CYthon or use whatever
>> underlying facility there is to speed it up.
>
>Speeding up this approach is pretty much futile IMHO. The parser gains
>speed from efficient I/O and memory management. Passing a byte at a time
>totally counters that (and even then it's only a *byte* at a time, not a
>*character* at a time).
>
>What I could imagine to do instead is to traverse the element tree and to
>do an incremental text search for each element tag (i.e. the regexp
>"<tagname\s") to recover the exact original positions. That would also
>allow you to work at the character level rather than the byte level
>(assuming that the editor works at that level, too). Searching for the
>above regexp is safe as "<" cannot occur anywhere in the XML data stream
>except for a tag start/end or comment/PI (ok, minus DTDs, but that's easy
>to catch using the line number of the root element).
>
>I will also check if there is a way to provide the position at the (target)
>parser level, but that needs to fit the current interface. And I currently
>do not have much time to dig into this.
>
>Stefan
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</PRE><PRE>Hi, all</PRE><PRE> I have tried to alter the libxml2 source to add a callback telling the current position when an element parsed. Now I wan't to know this position in lxml target parser. I don't know where and how to alter lxml source to add target parser event defination and event handler defination, so that my libxml2 new event(callback) can be processed. and I have nerver compile cython source before. Can any body give me some suggestion? </PRE><PRE> Thank you!</PRE><PRE>Best Regards</PRE><br><!-- footer --><br><span title="neteasefooter"/><hr/>
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