[xquery-talk] Function for determining one XPath as subset of another
W.S. Hager
wshager at gmail.com
Tue Jan 26 08:40:52 PST 2016
Hi Adam,
Perhaps it helps to start with rewriting the xpath expressions as pure
lambda expressions. Maybe that way you could apply lambda calculus?
Cheers,
Wouter
2016-01-26 17:26 GMT+01:00 Adam Retter <adam.retter at googlemail.com>:
> Given two simple XPaths, say:
>
> 1. //w
>
> 2. /x/y/z/w[@a = 'v']
>
> As a human I can very easily tell without evaluating the expressions
> that (2) will return a subset (or the same set) of the results that
> (1) would return *should* they both be evaluated.
>
> My goal here is given any two simple arbitrary XPaths expressed as
> strings, and without evaluating them against a context, to determine
> whether one would return a subset of the results of the other.
>
> I wondered if there might be an algorithm or library that someone
> already had or has written which might be able to give me the answer?
>
> I realise that I can only probably cover a subset of XPath itself, but
> it is only the path steps with predicates which I am interested in.
>
> Ideally I am looking for something in Java.
>
> --
> Adam Retter
>
> skype: adam.retter
> tweet: adamretter
> http://www.adamretter.org.uk
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>
--
W.S. Hager
Lagua Web Solutions
http://lagua.nl
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