RE: [xsl] Positional tests

Subject: RE: [xsl] Positional tests
From: "Paul Clarke" <pclarke@xxxxxxxxxxxxxxxx>
Date: Wed, 2 Mar 2005 19:26:23 -0000
Hi Wendell,

Thanks for your reply, I'm afraid I over-simplified things and I don't think
your suggestion will work.

Here's a true representation of my data. 

When processing font in block (3) or font in (4) I need to check back to see
if block(2) exists.

The structure is not the same in all cases as this XML originates from a

      <block>Anexo</block> (1)
      <block>Abreviaturas</block> (2)
                  <block> (3)
                    <font font-weight="bold">Abbreviation</font>
                  <block> (4)
                    <font font-weight="bold">Description</font>



-----Original Message-----
From: Wendell Piez [mailto:wapiez@xxxxxxxxxxxxxxxx] 
Sent: 02 March 2005 18:47
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: [xsl] Positional tests

Hi Paul,

At 01:17 PM 3/2/2005, you wrote:
>I need to find out if a block element that I process is the first one 
>with respect to its ancester S1, S2 or S3 elements. The hierarchy looks 
>something like this:
>         <root>
>           <S1>
>             <block> <<
>             <S2>
>                 <block> <<
>                 <block>
>               <S3>
>                 <body>
>                   <block> <<
>                   <p>
>                 <block>
>                 </body>
>                 </S3>
>             </S2>
>           </S1>
>         </root>
>I have tried:
>         test=". = ancestor::S3//block[1] or . = ancestor::S2//block[1] or
>= ancestor::S1//block[1]"
>But this slows down processing enormously.

Yes, it'll be slow (it does some heavy-duty tree traversal) -- and it won't
work, either. You can't test node identity with the "=" operator: it
compares string values.

"not(preceding-sibling::block)" will return true if the current node has no
preceding sibling blocks. Is your requirement different from this, and if
so, how?

For example, when you have


both blocks here pass the test I offered. Should they? (The second is not
"first with respect to its S3 ancestor".) Is your data constrained such that
this isn't a problem?


Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
Mulberry Technologies, Inc.      
17 West Jefferson Street                    Direct Phone: 301/315-9635
Suite 207                                          Phone: 301/315-9631
Rockville, MD  20850                                 Fax: 301/315-8285
   Mulberry Technologies: A Consultancy Specializing in SGML and XML

Current Thread