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Re: [xsl] compare two node sets

2020-01-19 14:49:29
Well, first of all we need to know which XSLT version we're talking about. It's 
certainly going to be difficult in XSLT 1.0.

It also depends on the performance requirement. The simplest solutions may well 
have quadratic performance, but since the number of directors and authors of a 
film is likely to be small, that may not matter.

The simplest (XPath 2.0) solution that comes to mind is

count(//director) eq count(//author) and 
every $d in //director satisfies 
  some $a in //author satisfies 
    deep-equal($d/*, $a/*)

Michael Kay
Saxonica

On 19 Jan 2020, at 20:36, Wolfhart Totschnig 
wolfhart(_dot_)totschnig(_at_)mail(_dot_)udp(_dot_)cl 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

Hello,

I have an XSL/XPath problem to which I cannot find the solution. I have an 
xml file with data about films, in the following form (simplified):

   <film>
      <title>The big Lebowski</title>
      <director>
         <first>Joel</first>
         <last>Coen</last>
      </director>
      <director>
         <first>Ethan</first>
         <last>Coen</last>
      </director>
      <author>
         <first>Ethan</first>
         <last>Coen</last>
      </author>
      <author>
         <first>Joel</first>
         <last>Coen</last>
      </author>
   </film>

I would like to test whether the director(s) of the film are the same as its 
writer(s) (here called "authors"). That is, I want to test whether for each 
<director> element there is an <author> element with the same child elements, 
and vice versa (i.e., for each <author> element a corresponding <director> 
element). So, in the above case, the test should return <true>. Note that the 
order of the <director>/<author> elements should not matter. By contrast, in 
the following example the test should return <false>:

   <film>
      <title>M</title>
      <director>
         <first>Fritz</first>
         <last>Lang</last>
      </director>
      <author>
         <first>Thea von</first>
         <last>Harbou</last>
      </author>
      <author>
         <first>Fritz</first>
         <last>Lang</last>
      </author>
   </film>

How can this be done?

To explain the purpose of this: When the test comes out true, the output will 
be "Written and directed by [names]", whereas otherwise it will be "Written 
by [names]. Directed by [names]".

Thanks in advance for your help!

Wolfhart

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