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<h1>GNU JAXP XSL transformer</h1>
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<div>
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This package contains a Java XSL transformer compliant with the JAXP
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specification. It depends on the GNU DOM and XPath implementations, and
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will generate GNU DOM nodes unless a specific target from another
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implementation was given. It understands DOM, SAX, and stream sources
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and result sinks and supports these JAXP features.
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</div>
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<div>
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To use this transformer, set the system property
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<code>javax.xml.transform.TransformerFactory</code> to the value
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<code>gnu.xml.transform.TransformerFactoryImpl</code>. You can then
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instantiate <a href='TransformerFactory.html'>TransformerFactory</a>
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and transformers in the ordinary manner. Reuse of stylesheets is
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supported using the JAXP <a href='Templates.html'>Templates</a>
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mechanism.
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</div>
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<h3>Architecture</h3>
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<div>
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When given a stylesheet source, this implementation compiles it internally
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into a Stylesheet object, which is a container for templates and state.
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Each stylesheet instruction is represented by a subclass of TemplateNode,
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which is arranged in a directed graph: each TemplateNode has a reference
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to its first child and the next node.
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</div>
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<div>
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The transformation process consists of identifying the Template that matches
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the root of the source context, and calling <code>apply</code> on its
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corresponding TemplateNode. This in turn processes its children and next
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TemplateNode, depending on the semantics of each node type.
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</div>
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<div>
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Template nodes may reference XPath expressions or patterns. These are fully
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compiled to objects of type <a href='../xpath/Expr.html'>Expr</a> at the
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time the stylesheet is compiled.
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</div>
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<h3>Conformance</h3>
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<div>
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This implementation is feature complete, but the XSLT specification is
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large and there are still many bugs that need to be ironed out. It has
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been tested against the OASIS XSLT TC test suite, comprising unit tests
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from the Xalan project and Microsoft. Conformance to these unit tests
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is approximately 70% at the current time, although normal usage of the
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transformer should involve relatively few surprises (the test suite is
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designed to test very complex and obscure functionality).
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</div>
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<h3>Known bugs</h3>
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<ul>
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<li>When reusing stylesheets using the JAXP Templates mechanism, XSL
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<code>apply-imports</code> instructions will not work.</li>
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<li>XPath filter expressions do not always work as expected (this is a
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problem with the GNU XPath implementation rather than the transformer).
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This can result in problems with the <code>position()</code> function,
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as well as <code>select</code> expressions and numbering.</li>
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</ul>
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<div>
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Obviously we'd like to improve conformance and fix these bugs. If you're
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interested in working on any of these issues please
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<a href='mailto:classpathx-xml@gnu.org'>contact us</a>.
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</div>
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</body>
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</html>
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