Optimizing XMLparsing with code generation
I was looking at some parsers using SAX recently, and was struck by the huge chains of if/elseif/else within the startElement and endElement callbacks. For example:
public void startElement(String uri, String
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Unfortunately, Xerces does not support this feature! /img/emoticons/sad.gif For my personal projects I try to use gnujaxp, which does, but applications that need to work with an arbitrary SAX parser cannot rely on interning.
But even with lame parsers we can now use the string-switching capabilities of CGLIB to gain back most of the speed of interning. I have checked net.sf.cglib.util.StringSwitcher into CVS. The API is very simple:
private static final int FOO = 0, BAR = 1, BAZ = 2;
private static final StringSwitcher SWITCHER =
StringSwitcher.create(new String[]{ \"foo\", \"bar\", \"baz\" },
new int[]{ FOO, BAR, BAZ },
true);
Of course the string and integer arrays can be as long as you want (it would not be worth it for only three). The third parameter is a boolean that indicates whether the switcher will only be called with strings from the argument array. For validated documents this is safe and gives a 3X speedup.
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parsing with code generation
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