XML query engines

[John Cowan]

Jarle Stabell scripsit:

> The basic idea is to assign an interval (using a pair of integers) to each 
> node, and assigning them such that Interval(n1) contains Interval(n2) if 
> and only if n2 is a subnode of n1.

Or, equivalently:
Assign a sequentially increasing number to each *tag* (start-tag or end-tag)
in the document, treating an empty tag as a start-tag followed by an
end-tag.  Then e1 is a descendant of e2 iff e1.start > e2.start
and e1.end < e2.end.  Also, e1 is a left sibling of e2 (and e2 is
a right sibling of e1) iff e1.end + 1 = e2.start; e1 is the leftmost
child of e2 iff e1.start = e2.start + 1.  Modeling the child/parent
relationship is not so easy, and requires iteration.

-- 
John Cowan					cowan at ccil.org
		e'osai ko sarji la lojban.

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