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Re: Internal entities removed from XML?

• To: Rick Jelliffe <ricko@a...>
• Subject: Re: Internal entities removed from XML?
• From: Rich Salz <rsalz@d...>
• Date: Thu, 19 Dec 2002 14:22:40 -0500
• Cc: Mike Champion <mc@x...>, xml-dev@l...
• In-reply-to: <009801c2a791$8c325300$4bc8a8c0@A...>
• References: <B885BEDCB3664E4AB1C72F1D85CB29F804B7C752@R...> <oprhnu8kjdezizxn@s...> <009801c2a791$8c325300$4bc8a8c0@A...>
• User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20021130

>>reflect the reality that I repeatedly hear about: one can make significant 
>>optimizations in an implementation if there is some understanding that 
>>there will be no entities to expand.  
> 
> 
> What are these optimizations?  

If you know that you only have to do < and &, then you can do 
inplace substitutions: you don't have to have mechanisms for switching 
to some alternate buffer, copying and pasting "raw" input into a 
normalized buffer to pass back to the user, etc.  When you see an & you 
can inline the character tests, not collecting the whole &...; into a 
lookup key, etc.  If I'm not using SAX, but am instead doing some kind 
of XML tokenizer (perhaps to be used in by a SAX library), "zero-copy" 
could mean avoiding lots of work:  I just pass the buffer back to the 
user directly.

Yes, you can write an optimized codepath that does this, falling back 
(or falling over :) when it finds other entities, but it should be clear 
that if you *never* have those things, then your code can be smaller 
(and therefore more reliable), and faster.

Make sense?
	/r$

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    • From: "Dare Obasanjo" <dareo@m...>
  • Re: Internal entities removed from XML?
    • From: Mike Champion <mc@x...>
  • Re: Internal entities removed from XML?
    • From: "Rick Jelliffe" <ricko@a...>

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