XOM API for Processing XML with Java

[Elliotte Harold <elharo AT metalab.unc.edu>]

The second new optimization I see here is avoiding the creation of 
intermediate string buffers for most calls to characters. Your 
measurements match my expectations that most of the time there'll be 
exactly one call to characters() per call to flushText(). The exceptions 
tend to occur on a  few corners:

1. Documents with very large (16K+) runs of plain, unmarked up text
2. A few parsers that call characters separately for entity and/or 
character references
3. One particularly brain-damaged older version of Xerces that actually 
invoked the characters() method once for each and every character in 
plain text that was loaded from entity references
4. A few parsers may call characters separately when a CDATA section 
interrupts non-CDATA section text

Only #1 is really worth considering when optimizing, and even that's 
uncommon.

The basic idea looks good. Given that more than one call to characters 
per text, I wonder if we can simplify it somewhat. Suppose we ignored 
StringBuffers completely? In other words, if characters was called a 
second or third time we just append directly to the string? This would 
leave the code about as simple as it is now, maybe simpler; and still 
take the same path as your patch for the 99% case where characters() is 
only called once. The hit wouldn't even be too bad when characters() was 
called more than once, because it almost never would be called more than 
two or three times. (Aside from the very weird #3 where performance 
would be abysmal, but honestly that really requires an updated parser.)

--
Elliotte Rusty Harold  elharo AT metalab.unc.edu
XML in a Nutshell 3rd Edition Just Published!
http://www.cafeconleche.org/books/xian3/
http://www.amazon.com/exec/obidos/ISBN=0596007647/cafeaulaitA/ref=nosim