Re: [xml-dev] isXPath1 / isXPath2 -- not(/..)

OK, I think I can explain this.

This XSLT 2.0 transformation:

<xsl:stylesheet version="2.0"  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 
  <xsl:template match="/">
    <xsl:copy-of select="/.. instance of item()*"/>
    <xsl:copy-of select="(4=5)=/.."/>
  </xsl:template>
</xsl:stylesheet>

produces:

true false

The **general comparison**:

(4=5) = /..

is equivalent to:

false() = ()

On the left side we have a sequence of one item.

On the right side we have a sequence of 0 items.

Therefore the second (empty) sequence has no item that is the Boolean false()  and thus the expression evaluates to false()

On Sat, Dec 19, 2015 at 9:49 AM, Dimitre Novatchev <[email protected]> wrote:

On Sat, Dec 19, 2015 at 9:22 AM, Hermann Stamm-Wilbrandt <[email protected]> wrote:

"(4=5)=/.."  

There seems to be something wrong with the type evaluation of Saxon 9.1J

When I evaluate this:

   /.. instance of item()

the result is:

  false()

As item() is the root of the type system and every possible value is an item(), the above result means that  /..  has type that isn't defined anywhere in the type system.

Seems this has something to do with the "highest possible derived type", or is just a bug.

Also, we do need a     type-of(expr)    function.

Any thoughts, please?


--

Cheers,

Dimitre Novatchev

---------------------------------------

Truly great madness cannot be achieved without significant intelligence.

---------------------------------------

To invent, you need a good imagination and a pile of junk

-------------------------------------

Never fight an inanimate object

-------------------------------------

To avoid situations in which you might make mistakes may be the

biggest mistake of all

------------------------------------

Quality means doing it right when no one is looking.

-------------------------------------

You've achieved success in your field when you don't know whether what you're doing is work or play

-------------------------------------

To achieve the impossible dream, try going to sleep.

-------------------------------------

Facts do not cease to exist because they are ignored.

-------------------------------------

Typing monkeys will write all Shakespeare's works in 200yrs.Will they write all patents, too? :)

-------------------------------------

Sanity is madness put to good use.

-------------------------------------

I finally figured out the only reason to be alive is to enjoy it.