Re: [xsl] XPath expression to check that there are no intervening elements?

["Dimitre Novatchev dnovatchev@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

XPath 1.0:

 not(B[1]/following-sibling::node()[not(position() >
../count(B))][not(self::B)])

XPath 2.0:

not(node()[. >> ../B[1] and . << ../B[last()]][not(self::B)])

Cheers,
Dimitre

On Tue, Jul 19, 2016 at 9:16 AM, G. Ken Holman g.ken.holman@xxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> I like Mike's answer for XSLT 2.
>
> Your XSLT 1 solution can be improved by reducing the number of counting
> actions.  Your solution has three uses of count() ... this has only two:
>
>   count(B[last()]/preceding-sibling::*[not(self::B)]) =
>   count(B[1]/preceding-sibling::*[not(self::B)])
>
> Avoiding the use of counting you could do the following:
>
>   string( generate-id( B[1]/preceding-sibling::*[not(self::B)][1] ) ) =
>   string( generate-id( B[last()]/preceding-sibling::*[not(self::B)][1] ) )
>
> The use of string() is necessary in case the sequence of children starts
> with B.
>
> Come to think of it, neither your answer, Mike's answer nor my answer will
> work if there are no B children at all.  You will get a false positive.
> Does your test need to accommodate that situation?
>
> . . . . . . . . Ken
>
> At 2016-07-19 15:44 +0000, Costello, Roger L. costello@xxxxxxxxx wrote:
>>
>> Hi Folks,
>>
>> This XML has a solid block of <B> elements:
>>
>> <Document>
>>     <A/>
>>     <B/>
>>     <B/>
>> </Document>
>>
>> This XML has an intervening <C> element:
>>
>> <Document>
>>     <A/>
>>     <B/>
>>     <C/>
>>     <B/>
>> </Document>
>>
>> I need an XPath expression to return a Boolean value:
>>
>>         Return true if there is one solid block of <B> elements
>>                 (no intervening elements).
>>         Otherwise, return false.
>>
>> I created a horrendous XPath expression to solve it:
>>
>> count(B) eq (B[last()]/count(preceding-sibling::*)+1 -
>> B[1]/count(preceding-sibling::*))
>>
>> Can you provide a better (simpler, more efficient) XPath expression?
>>
>> /Roger
>>
>
>
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-- 
Cheers,
Dimitre Novatchev
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