Cart
|
[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Features of XML Languages that Increase Complexity?
 I am sure Roger will be happy to know that if someone implements XML as a conforming SGML system, implementing the SGML Declaration at then they are limited to 99,999,999 characters, which is the maximum that SGML allowed (or something like that: TOTALCAP). AFAIK XML documents with this restriction would behttp://www.w3.org/TR/NOTE-sgml-xml-971215 of the theoretical class recursive rather then recusively enumerable. But to a more general point, the problem underlying Rogers comments are, I think, that considering documents using language-theoretic ideas is probably not as useful as it may appear:
Take problem 4 above. If we have a document (i.e. it is sitting, finite, in memory), then finding out whether an IDREF matches an ID is an linear O(n) operation (2 passes).
In a way, this gives us a two-stage grammar: an upper language (the document is a sequence of bytes that must fit into virtual memory) and a low language (XML or whatever) where the first language excludes infinite documents, and some of the theoretical characteristics that attach to them. SGML allowed a document to state how much capacity it required, and for an implementation to state what capacity it provided: for example, for the number of attribute it could handle. This is a relic of 1980s capacities, but it is amazing that 30 years later there are still issues in the same kind of area! Cheers Rick 
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] |
PURCHASE STYLUS STUDIO ONLINE TODAY!Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced! 
Download The World's Best XML IDE!Accelerate XML development with our award-winning XML IDE - Download a free trial today! Subscribe in XML format
|
|||||||||
