Re: [Exist-open] Boolean or not Boolean ?

[Michael B. <mbe...@mb...>]

Ah well, the first posting wasn't an accurate reduction of the actual code
that gave rise to the issue.

Now we've seen that code, here's my attempt at a reducing it, and I do think
it indicates a problem:

VERSION 1
for $element in ("black")
return
   <r>
   <c1>
   {
     $element eq "black" or  $element eq "white"
   }
   </c1>
   <c2>
   {
     $element eq "black" and $element eq "white"
   }
   </c2>
   <c1_AND_c2>
   {

     ($element eq "black" or  $element eq "white") and ($element eq "black"
and $element eq "white")

   }
   </c1_AND_c2>
  </r>


Now this version produces the result you were expecting:

<r>
    <c1>true</c1>
    <c2>false</c2>
    <c1_AND_c2>false</c1_AND_c2>
</r>


But let's now remove the parentheses used to constrain the sequence of
Boolean evaluations, giving

VERSION 2:
for $element in ("black")
return
   <r>
   <c1>
   {
     $element eq "black" or  $element eq "white"
   }
   </c1>
   <c2>
   {
     $element eq "black" and $element eq "white"
   }
   </c2>
   <c1_AND_c2>
   {

     $element eq "black" or  $element eq "white" and $element eq "black" and
$element eq "white"

   }
   </c1_AND_c2>
  </r>

NOW we get what you are reporting:

<r>
    <c1>true</c1>
    <c2>false</c2>
    <c1_AND_c2>true</c1_AND_c2>
</r>


I leave it to Pierrick and others more used to doing battle with the
increasingly convoluted specs to decide whether each of those results is
correct (AFAIK they both are). But I would say that the original code has
the pattern of grouping parentheses found in VERSION1, yet it is producing
the result of VERSION2. Which may well indicate a problem with eXist's
XQuery compiler.

Michael Beddow