[xslt] libxslt: xsl:include/import cache?

[Elizabeth Mattijsen <liz dijkmat nl>]

I've been looking for ways to reduce the memory usage of a web-server that 
will have a _lot_ of stylesheets, many of which will be referring to the 
same "subroutine" templates by using <xsl:include>.

I understand that <xsl:include> is basically inserting the XML at the 
position where it is called.  So, each time a stylesheet is included with 
<xsl:include>, new memory is allocated and used (as far as I can see, anyway).

I've been looking at the following lines in "libxslt/imports.c":
------------------------------------------------------------------
     include = xsltLoadStyleDocument(style, URI);
     if (include == NULL) {
         xsltPrintErrorContext(NULL, style, cur);
         xsltGenericError(xsltGenericErrorContext,
             "xsl:include : unable to load %s\n", URI);
         goto error;
     }

     oldDoc = style->doc;
     style->doc = include->doc;
     xsltParseStylesheetProcess(style, include->doc);
     style->doc = oldDoc;
--------------------------------------------------------------------

 From this I conclude that for a given URI, memory is allocated and a 
pointer is returned by xsltLoadStyleDocument().  And then later that 
pointer is used to integrate into the "parent" stylesheet.

Would it be _too_ simplistic to create a memory cache, keyed to URI, that 
would save the "include" pointer and return that if the stylesheet at that 
URI was already loaded before?  And this save a _lot_ of memory when 
multiple stylesheets use the same stylesheet through <xsl:include>?

Or are there other issues that would prevent this from working?


Elizabeth Mattijsen