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