Implementing custom Saxon collation URI resolvers
Custom collation URI resolvers
Plug-ins can provide custom URI resolvers that provide collators for specific collation URIs.
Saxonservice
Antjar
xsl:sort
Chinese
I18Nplug-in
plug-ins
plug-ins
XSLTURI resolver
To do custom sorting and grouping in XSLT, you identify collators using URIs that Saxon resolves to collator
implementations. You implement the mapping from collation URIs to collators through custom collation URI
resolvers.
For example, the DITA Community I18N plugin provides a custom collator for doing dictionary-based sorting and
grouping of Simplified Chinese.
To allow multiple plug-ins to contribute collation URI resolvers, DITA-OT defines a superinterface of Saxon’s
CollationUriResolver interface,
org.dita.dost.module.saxon.DelegatingCollationUriResolver, that takes a base resolver.
Implementations of DelegatingCollationUriResolver should delegate to their base resolver if they
do not resolve the URI specified on the resolve request. When multiple plug-ins provide resolvers it results in a
chain of resolvers, ending with the built-in Saxon default resolver.
The order in which plug-ins will be processed during collation URI resolver configuration is variable, so two
plug-ins should not try to resolve the same collation URI. In that case the first one configured will be used at
run time.
A typical delegating collation URI resolver looks like
this:public class DCI18nCollationUriResolver implements DelegatingCollationUriResolver {
public static final String DITA_COMMUNITY_I18N_ZH_CNAWARE_COLLATOR =
"http://org.dita-community.i18n.zhCNawareCollator";
public static final String LANG_URI_PARAM = "lang";
private CollationURIResolver baseResolver;
public DCI18nCollationUriResolver() {
super();
this.baseResolver = StandardCollationURIResolver.getInstance();
}
public net.sf.saxon.lib.StringCollator resolve(String uri, Configuration configuration)
throws XPathException {
ZhCnAwareCollator collator = resolveToZhCnAwareCollator(uri, null, configuration);
if (null == collator) {
return baseResolver.resolve(uri, configuration);
}
return (StringCollator) collator;
}
@Override
public void setBaseResolver(CollationURIResolver baseResolver) {
this.baseResolver = baseResolver;
}
/* ... Code to evaluate the collation URI and provide the appropriate collator goes here */
}
To implement a custom collation URI resolver:
- Add your plugin’s JAR file in the DITA-OT class path as described in .
- Implement an instance of org.dita.dost.module.saxon.DelegatingCollationUriResolver as
described above.
- Include a file named org.dita.dost.module.saxon.DelegatingCollationUriResolver in the
directory META-INF/services in the compiled JAR that your plug-in provides. Each line of
the file must be the name of a class that implements
org.dita.dost.module.saxon.DelegatingCollationUriResolver:org.example.i18n.saxon.MyCollationUriResolver
You can create the services file using service elements in an Ant
jar
task:<jar destfile="${basedir}/target/lib/example-saxon.jar">
⋮
<service type="org.dita.dost.module.saxon.DelegatingCollationUriResolver">
<provider classname="org.example.i18n.saxon.MyCollationUriResolver"/>
</service>
⋮
</jar>
- To use the collator in XSLT style sheets, specify the collation URI on xsl:sort elements (or
anywhere a collator URI can be
specified):<xsl:apply-templates select="word">
<xsl:sort collation="http://org.example.i18n.MyCollator"/>
</xsl:apply-templates>