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-<html>
-<head>
- <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
- <title>Apache Lucene Flexible Query Parser</title>
-</head>
-<body>
-
-<h2>Apache Lucene Flexible Query Parser</h2>
-
-<p>
-This contrib project contains the new Lucene query parser implementation, which matches the syntax of the core QueryParser but offers a more modular architecture to enable customization.
-</p>
-
-<p>
-It's currently divided in 2 main packages:
-<ul>
-<li>{@link org.apache.lucene.queryParser.core}: it contains the query parser API classes, which should be extended by query parser implementations. </li>
-<li>{@link org.apache.lucene.queryParser.standard}: it contains the current Lucene query parser implementation using the new query parser API.</li>
-</ul>
-</p>
-
-<h3>Features</h3>
-
- <ol>
- <li>Full support for boolean logic (not enabled)</li>
- <li>QueryNode Trees - support for several syntaxes,
- that can be converted into similar syntax QueryNode trees.</li>
- <li>QueryNode Processors - Optimize, validate, rewrite the
- QueryNode trees</li>
- <li>Processors Pipelines - Select your favorite Processor
- and build a processor pipeline, to implement the features you need</li>
- <li>Config Interfaces - Allow the consumer of the Query Parser to implement
- a diff Config Handler Objects to suite their needs.</li>
- <li>Standard Builders - convert QueryNode's into several lucene
- representations. Supported conversion is using a 2.4 compatible logic</li>
- <li>QueryNode tree's can be converted to a lucene 2.4 syntax string, using toQueryString</li>
- </ol>
-
-<h3>Design</h3>
-<p>
-This new query parser was designed to have very generic
-architecture, so that it can be easily used for different
-products with varying query syntaxes. This code is much more
-flexible and extensible than the Lucene query parser in 2.4.X.
-</p>
-<p>
-The new query parser goal is to separate syntax and semantics of a query. E.g. 'a AND
-b', '+a +b', 'AND(a,b)' could be different syntaxes for the same query.
-It distinguishes the semantics of the different query components, e.g.
-whether and how to tokenize/lemmatize/normalize the different terms or
-which Query objects to create for the terms. It allows to
-write a parser with a new syntax, while reusing the underlying
-semantics, as quickly as possible.
-</p>
-<p>
-The query parser has three layers and its core is what we call the
-QueryNode tree. It is a tree that initially represents the syntax of the
-original query, e.g. for 'a AND b':
-</p>
-<pre>
- AND
- / \
- A B
-</pre>
-<p>
-The three layers are:
-</p>
-<dl>
-<dt>QueryParser</dt>
-<dd>
-This layer is the text parsing layer which simply transforms the
-query text string into a {@link org.apache.lucene.queryParser.core.nodes.QueryNode} tree. Every text parser
-must implement the interface {@link org.apache.lucene.queryParser.core.parser.SyntaxParser}.
-Lucene default implementations implements it using JavaCC.
-</dd>
-
-<dt>QueryNodeProcessor</dt>
-<dd>The query node processors do most of the work. It is in fact a
-configurable chain of processors. Each processors can walk the tree and
-modify nodes or even the tree's structure. That makes it possible to
-e.g. do query optimization before the query is executed or to tokenize
-terms.
-</dd>
-
-<dt>QueryBuilder</dt>
-<dd>
-The third layer is a configurable map of builders, which map {@link org.apache.lucene.queryParser.core.nodes.QueryNode} types to its specific
-builder that will transform the QueryNode into Lucene Query object.
-</dd>
-
-</dl>
-
-<p>
-Furthermore, the query parser uses flexible configuration objects. It also uses message classes that
-allow to attach resource bundles. This makes it possible to translate
-messages, which is an important feature of a query parser.
-</p>
-<p>
-This design allows to develop different query syntaxes very quickly.
-</p>
-
-<h3>StandardQueryParser and QueryParserWrapper</h3>
-
-<p>
-The standard (default) Lucene query parser is located under
-org.apache.lucene.queryParser.standard.
-<p>
-To make it simpler to use the new query parser
-the class {@link org.apache.lucene.queryParser.standard.StandardQueryParser} may be helpful,
-specially for people that do not want to extend the Query Parser.
-It uses the default Lucene query processors, text parser and builders, so
-you don't need to worry about dealing with those.
-
-{@link org.apache.lucene.queryParser.standard.StandardQueryParser} usage:
-
-<pre class="prettyprint">
- StandardQueryParser qpHelper = new StandardQueryParser();
- StandardQueryConfigHandler config = qpHelper.getQueryConfigHandler();
- config.setAllowLeadingWildcard(true);
- config.setAnalyzer(new WhitespaceAnalyzer());
- Query query = qpHelper.parse("apache AND lucene", "defaultField");
-</pre>
-<p>
-To make it easy for people who are using current Lucene's query parser to switch to
-the new one, there is a {@link org.apache.lucene.queryParser.standard.QueryParserWrapper} under org.apache.lucene.queryParser.standard
-that keeps the old query parser interface, but uses the new query parser infrastructure.
-</p>
-
-</body>
-</html>
fnp / pylucene.git / blobdiff