Re: [xsl] Efficient Recursive Algorithms in XSLT (Was: Re: Constructing X number of elements)

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

With respect,

We've given Ilkka the simple recursive solution. And Dimitre has reminded 
us that in the general case, there are also better approaches. But Ilkka's 
problem may not need to be solved in the general case.

For example, let's assume there will never be more than five stars.

<my:stars> <!-- you'll need to have declared the 'my' namespace -->
  <img src="star.gif" alt="first star"/>
  <img src="star.gif" alt="second star"/>
  <img src="star.gif" alt="third star"/>
  <img src="star.gif" alt="fourth star"/>
  <img src="star.gif" alt="fifth star"/>
</my:stars>

<xsl:variable name="stars" select="document('')/*/my:stars/img"/>

Then,
<xsl:template match="movie">
  ...
  <xsl:copy-of select="$stars[position() &lt;= @rating]" />
  ...
</xsl:template>

This is neat, efficient, does not rely on recursion with its ungainliness 
and potential performance hit (as if that were likely to be a problem at 
five levels), and is easily extended to handle, say, a maximum of seven or 
nine stars. The stars can even be different.

It's a refinement of Chris's solution.

Cheers,
Wendell

At 10:42 AM 8/21/01, Dimitre wrote:
> This solution will crash some XSLT processors and is generally less 
> efficient (both
> in time and space) than another general approach for implementing recursive
> algorithms....



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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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