Re: [xsl] Filtering on a tokenized list

["Martin Honnen martin.honnen@xxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

On 23.02.2017 13:49, Rick Quatro rick@xxxxxxxxxxxxxx wrote:

> I have an attribute value that I want to convert to a sequence of decimals:
>
> @colwidth="0.439in 1.845in"
>
> I am using tokenize to drop the measurement units before I convert each
> member to decimal:
>
> tokenize($widths,'[^\.\d]')
>
> This works, except I get a empty string as the last item in the list. I saw
> in Michael's book that I can filter out the empty member with a predicate:
>
> tokenize($widths,'[^\.\d]')[.]
>
> I can't quite understand how the predicate [.] works. Is it like saying
> "non-empty strings"? Would it be equivalent to
>
> [not(.="")]

tokenize returns a sequence of strings and then then the predicate [.] 
applied to the sequence of strings checks the boolean value of each 
string and empty strings, when converted to a boolean, are false while 
non-empty strings are true.

If you check https://www.w3.org/TR/xpath-30/#id-filter-expression then 
it says

The predicate truth value is derived by applying the following rules, in 
order:

    If the value of the predicate expression is a singleton atomic 
value of a numeric type or derived from a numeric type, the predicate 
truth value is true if the value of the predicate expression is equal 
(by the eq operator) to the context position, and is false otherwise. 
[Definition: A predicate whose predicate expression returns a numeric 
type is called a numeric predicate.]

    Otherwise, the predicate truth value is the effective boolean value 
of the predicate expression.


and https://www.w3.org/TR/xpath-30/#id-ebv says

If its operand is a singleton value of type xs:string, xs:anyURI, 
xs:untypedAtomic, or a type derived from one of these, fn:boolean 
returns false if the operand value has zero length; otherwise it returns 
true.