XOM API for Processing XML with Java

[Wolfgang Hoschek <whoschek AT lbl.gov>]

On Jun 29, 2005, at 4:29 AM, Elliotte Harold wrote:


> Wolfgang Hoschek wrote:
>
>
>
> >   private static final boolean mightNeedAttributeEscaping(String  
> > s)  { // WH
>
>
> Why "might"? Is there any case in which this method would return  
> true and attribute escaping would not be needed?

because adjustingWhiteSpace() might be false. See writeAttributeValue 
(char c)


> Also I'm guessing a lot of the speedup comes from writing the data  
> as one string, rather than a character at a time.

Right.


> However this approach still needs to loop through the whole string  
> if it's going down the fast path. It can short circuit but the  
> result of that is going down the slow path instead. What if in this  
> loop we simply built up a new StringBuffer containing the escaped  
> string and then wrote that? Could that be faster for both cases? Or  
> would the extra time spent in building the StringBuffer kill any  
> advantages?

Checking each char in the string appears to be cheap IFF the loop is  
very tight and there's very little code in it, probably because of  
much more efficient inlining, unrolling, and other optimizations. The  
large complicated body with virtual calls of the slow non-Unicode  
methods taking care of the general case effectively prevents the  
compiler from doing a good job.

Wolfgang.