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| <title>Help System extension points: Lucene Analyzer</title> | |
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| Lucene Analyzer</h1></center> | |
| <b><i>Identifier: </i></b>org.eclipse.help.luceneAnalyzer | |
| <p><b><i>Description: </i></b>This extension point is used to register | |
| text analyzers for use by by help when indexing and searching documentation. | |
| <p>Help exploits capabilities of the Lucene search engine, that allows | |
| indexing of token streams (streams of words). Analyzers create tokens | |
| from the character stream. They examine text content and provide | |
| tokens for use with the index. The text stream can be tokenized in | |
| many unique ways. A trivial analyzer can tokenize streams at white | |
| space, a different one can perform filtering of tokens, based on the application | |
| needs. Since the documentation is mostly human readable text, it | |
| is desired that analyzers used by the help system perform language and | |
| grammar aware tokenization and normalization of indexed text. For | |
| some languages the quality of search increases significantly if stop word | |
| removal and stemming is performed on the indexed text. This extension | |
| points allows configuring analyzers for the languages that default help | |
| system does not provide language aware analyzers. | |
| <p><b><i>Configuration Markup:</i></b> | |
| <p><tt> <!ELEMENT analyzer EMPTY></tt> | |
| <br><tt> <!ATTLIST analyzer</tt> | |
| <br><tt> locale | |
| CDATA #REQUIRED</tt> | |
| <br><tt> class | |
| CDATA #REQUIRED</tt> | |
| <br><tt> ></tt> | |
| <ul> | |
| <li> | |
| <b>locale -</b> a string identifying locale for which the supplied analyzer | |
| is to be used, it two letters language is provided, the analyzer will be | |
| available to all locales of that language</li> | |
| <li> | |
| <b>class</b> - a fully qualified name of the Java class extending <tt>org.apache.lucene.analysis.Analyzer</tt></li> | |
| </ul> | |
| <b><i>Examples:</i></b> | |
| <p>Following is an example of Lucene Analyzer configuration: | |
| <p><tt> <extension id="com.xyz.XYZ" point="org.eclipse.help.luceneAnalyzer"></tt> | |
| <br><tt> <analyzer locale="ll_CC" | |
| class="com.xyz.ll_CCAnalyzer" /></tt> | |
| <br><tt> </extension></tt> | |
| <p><b><i>API Information</i>:</b> | |
| <p>The value of the <tt>locale</tt> attribute must represent either a five | |
| or two character locale string. If analyzer is configured for a language | |
| by specifying two letter language designation, the analyzer is going to | |
| be used for all locales of this language. If analyzer is configured | |
| that matches five characters locale, it is going to be used instead. | |
| <p>The value of the <tt>class</tt> attribute must represent a class that | |
| extends <tt>org.apache.lucene.analysis.Analyzer</tt>. It is recommended | |
| that this analyzer performs lowercase filtering for languages where it | |
| is possible to increase number of search hits by making search case insensitive. | |
| <p><b><i>Supplied Implementation: </i></b>Help system comes with English | |
| and German analyzers, that are configured to be used for en and de locales | |
| respectively. These analyzers perform stop word filtering, lowercase | |
| filtering, and stemming. For languages that no analyzers are | |
| configured, help uses simple analyzer that performs lowercase filtering | |
| and English stop word filtering. | |
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