Re: [basex-talk] hof:until is gone?

This feels like an ideal use case for XSLT for-each-group—something that is challenging to implement in XQuery.

Cheers,

E.

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From: BaseX-Talk basex-talk-bounces@mailman.uni-konstanz.de on behalf of Graydon Saunders graydonish@gmail.com Date: Thursday, March 28, 2024 at 7:43 AM To: BaseX BaseX-Talk@mailman.uni-konstanz.de Subject: [basex-talk] hof:until is gone? [External Email]

________________________________ Hello --

So I'm trying to do this:

import module namespace xcs = "http://www.xcential.com/xquery/utils/scripthttp://www.xcential.com/xquery/utils/script" at "same-words-same-order-script.xqm"; (: we don't need xc computationally but there are external variables in that namespace in scope :) import module namespace xc = "http://www.xcential.com/xquery/utilshttp://www.xcential.com/xquery/utils" at 'same-words-same-order.xqm';

declare function xc:dropTableLines($in as node()*,$toggle as xs:boolean) as node()* { switch (true()) case empty($in) return () case starts-with(head($in),':stab') return (<line/>,xc:dropTableLines(tail($in),true())) case starts-with(head($in),':rtab') return (<line/>,xc:dropTableLines(tail($in),false())) case $toggle return (<line/>,xc:dropTableLines(tail($in),$toggle)) default return (head($in),xc:dropTableLines(tail($in),$toggle)) };

let $test as element() := <text> <line></line> <line></line> <line>:stab</line> <line>weasels</line> <line>:stab</line> <line>weasels</line> <line></line> <line></line> <line>:rtab.</line> <line></line> <line>asparagus</line> <line></line> <line></line> <line>:stab</line> <line></line> <line>weasels</line> <line>:rtab.</line> <line>asparagus</line> <line>asparagus</line> <line>asparagus</line> <line>asparagus</line> <line>asparagus</line> <line>:stab</line> <line>:stab</line> <line></line> <line></line> <line>:stab</line> <line></line> <line>weasels</line> <line></line> <line>:rtab.</line> <line></line> <line>asparagus</line> <line></line> <line></line> <line></line> </text>

return element {'text'} { xc:dropTableLines($test/line,false()) }

Only at scale the stack blows up and I get the "try tail recursion?" suggestion. I would have tried hof:until for that, since I have to pass the current state of "are we dropping or not dropping intervening content?", but it looks like it's been removed? And the available hof functions in 4 look like they're strictly positional which is actively unhelpful in this case. (At least with whatever brain cells I currently have.)

What's the appropriate pattern for "process a sequence, toggling an action on or off based on the last member of the sequence we looked at?"

Thanks! Graydon