XOM API for Processing XML with Java

[Wolfgang Hoschek <whoschek AT lbl.gov>]

> I can't imagine that there'll be that many or frequent calls to 
> setInternalDTDSubset, but if this actually proves to be a performance 
> hit, then maybe I can explore using ThreadLocals instead.

It doesn't occur in my use cases, but if one had an app that exchanges 
many identically formed small XML protocol messages and that app 
happened to use internal DTD subsets it would take a large hit. So more 
immediately useful than a ThreadLocal is a small string cache similar 
in spirit to Verifier.URICache. I think that should eliminate problems 
for all but bizarre use cases. Checking for a cache hit with == doesn't 
make much sense here; one needs to check with equals(). I think keeping 
the same cache size (6) is just fine.

I just hacked this together by adding a containsEqual(String) method to 
Verifier.URICache. Like this:

        boolean containsEqual(String s) {
            for (int i = 0; i < LOAD; i++) {
                if (s.equals(cache[i])) return true;
            }
            return false;
        }

[With that URICache might perhaps better be called "StringCache".]
And checkInternalDTDSubset(String subset) now reads:

    // For use in checking internal DTD subsets
    private static XMLReader parser;
        private static URICache internalDTDSubsetCache = new URICache();

    static synchronized void checkInternalDTDSubset(String subset) {
            if (internalDTDSubsetCache.containsEqual(subset)) return;

        ... checking goes here same as before

        internalDTDSubsetCache.put(subset);
    }

Thoughts?
Wolfgang.