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| <!-- $Id$ --> |
| <s1 title="<xsl:include> / <xsl:import>"> |
| |
| <s2 title="Contents"> |
| <ul> |
| <li><link anchor="functionality">Functionality</link></li> |
| <li><link anchor="implementation">Implementation</link></li> |
| </ul> |
| </s2> |
| |
| <anchor name="functionality"/> |
| <s2 title="Functionality"> |
| |
| <p><code><xsl:include></code> allows you to include one stylesheet |
| into another. The includ<em>ed</em> stylesheet's templates will have the same |
| default priorities and import precedence as the includ<em>ing</em> stylesheet. |
| <code><xsl:import></code> offers the same, but the import precedence |
| of elements in an import<em>ed</em> stylesheet is always less than that of |
| the import<em>ing</em> stylesheet.</p> |
| |
| </s2> |
| |
| <anchor name="implementation"/> |
| <s2 title="Implementation"> |
| |
| <anchor name="include"/> |
| <s3 title="<xsl:include>"> |
| |
| <p>This is the simplest case, so we will look at that first. The algorithm |
| for including another stylesheet is roughly:</p> |
| |
| <ul> |
| <li>get the including stylesheet from the XSLT parser</li> |
| <li>get the value of the "href" attribute from the |
| <code><xsl:include></code> element and check for circular |
| includes/imports</li> |
| <li>check if there is a defined <code>SourceLoader</code> set either |
| through the native or the TrAX API</li> |
| <li>get an <code>InputSource</code> for the document to include, either |
| from the <code>SourceLoader</code> or from the document's URI</li> |
| <li>parse the input document using the compiler's XSLT parser</li> |
| <li>set the import precedence of the included stylesheet to the same as |
| the import precedence of the including stylesheet</li> |
| <li>get the top-level stylesheet from the XSLT parser</li> |
| <li>move all variables, parameters, and top-level elements (include |
| templates) from the included stylesheet to the top-level stylesheet |
| (all elements will keep their import precedence even after being moved |
| to the top-level stylesheet)</li> |
| </ul> |
| |
| </s3> |
| |
| <anchor name="import"/> |
| <s3 title="<xsl:import>"> |
| |
| <p>This is very similar to <code><xsl:include></code>, but import |
| precedence has to be handled differently. Looking at the code you'll find |
| this fragment:</p><source> |
| // Handle precedence for the including stylesheet |
| final int currPrecedence = parser.getCurrentImportPrecedence(); |
| final int nextPrecedence = parser.getNextImportPrecedence(); |
| _imported.setImportPrecedence(currPrecedence); |
| context.setImportPrecedence(nextPrecedence);</source> |
| |
| <p>The important thing here is that the imported stylesheet has import |
| precedence <em>less</em> than the importing stylesheet. So the imported |
| stylesheet gets the current import precedence, while the current stylesheet |
| gets the next available (unused) import precedence. The |
| <code>Stylesheet</code> class has a method |
| <code>setImportPrecedence()</code> that ensures that the import precedence |
| is set not only for the stylesheet itself, but that it is also propagated |
| down to any included/imported stylesheets:</p><source> |
| public void setImportPrecedence(final int precedence) { |
| // Set import precedence for this stylesheet |
| _importPrecedence = precedence; |
| |
| // Set import precedence for all included stylesheets |
| final Enumeration elements = elements(); |
| while (elements.hasMoreElements()) { |
| SyntaxTreeNode child = (SyntaxTreeNode)elements.nextElement(); |
| if (child instanceof Include) { |
| Stylesheet included = ((Include)child).getIncludedStylesheet(); |
| if (included != null) included.setImportPrecedence(precedence); |
| } |
| } |
| |
| // Set import precedence for the stylesheet that imported this one |
| if (_importedFrom != null) { |
| if (_importedFrom.getImportPrecedence() < precedence) { |
| final Parser parser = getParser(); |
| final int nextPrecedence = parser.getNextImportPrecedence(); |
| _importedFrom.setImportPrecedence(nextPrecedence); |
| } |
| } |
| // Set import precedence for the stylesheet that included this one |
| else if (_includedFrom != null) { |
| if (_includedFrom.getImportPrecedence() != precedence) |
| _includedFrom.setImportPrecedence(precedence); |
| } |
| }</source> |
| |
| <p>This method has been carefully cluttered together, and it works, and it |
| should not be touched.</p> |
| |
| </s3> |
| |
| <anchor name="apply-imports"/> |
| <s3 title="<xsl:apply-imports>"> |
| |
| </s3> |
| |
| </s2> |
| |
| </s1> |