Re: [xsl] this script converts an instance path to an RNG path

[S Woodside <sbwoodside@xxxxxxxxx>]

How it works ...

On Monday, March 31, 2003, at 06:02  PM, S Woodside wrote:

It's a recursive template, $fragment gets ever shorter, it pulls steps 
off the front of the string.

>   <!-- Converts an instance path to an RNG path -->
>   <xsl:template name="inst2rngPath">
>     <xsl:param name="fragment"/>

fragment must be an XPath string from an instance document that 
conforms to a given RNG grammar

>     <xsl:choose>
>       <xsl:when test="starts-with($fragment, '/')">  <!-- strip 
> beginning / -->
>         <xsl:call-template name="inst2rngPath">
>           <xsl:with-param name="fragment" 
> select="substring-after($fragment, '/')"/>
>         </xsl:call-template>
>       </xsl:when>

That section eliminates any leading "/" if there is one and recurses 
without it.

This section inserts //*[@name=' ...  (since the instance node steps 
are encoded into the RNG as attributes called "name"). There can be 
arbitrary steps inbetween name-defining nodes in RNG that might define 
optional, zeroOrMore, etc. so // just skips them.

> <xsl:otherwise>
>         <xsl:text>//*[@name='</xsl:text>

this section coming up will insert a single step in the XPath.

>         <xsl:choose>
> <xsl:when test="substring-before($fragment, '/')">
>             <xsl:value-of select="substring-before($fragment, '/')"/>
>           </xsl:when><xsl:otherwise>
>             <xsl:value-of select="$fragment"/>
>         </xsl:otherwise></xsl:choose>
>         <xsl:text>']</xsl:text>

It used a choose because the substring-before() xpath function returns 
nothing if the "before" string isn't found (as opposed to returning the 
whole string) so that if this is the last recursive step, and there is 
no "/" it will just select $fragment

Now we will either recurse if there's something left to process, or 
stop recursing

>         <xsl:choose>
>           <xsl:when test="contains($fragment, '/')">  <!-- recursive 
> step -->
>             <xsl:call-template name="inst2rngPath">
>               <xsl:with-param name="fragment" 
> select="substring-after($fragment, '/')"/>
>             </xsl:call-template>

that recursed after snipping off the first node step

>           </xsl:when><xsl:otherwise>  <!-- default step -->
>             <xsl:text>/*</xsl:text>
>           </xsl:otherwise>

that add /* to the end to select all children (maybe not necessary 
though)

>         </xsl:choose>
>       </xsl:otherwise>
>     </xsl:choose>
>   </xsl:template>
That's all.

simon


XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list