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See:
Description
Packages | |
---|---|
org.apache.lucene.queryParser.core | Contains the core classes of the flexible query parser framework |
org.apache.lucene.queryParser.core.builders | Contains the necessary classes to implement query builders |
org.apache.lucene.queryParser.core.config | Contains the base classes used to configure the query processing |
org.apache.lucene.queryParser.core.messages | Contains messages usually used by query parser implementations |
org.apache.lucene.queryParser.core.nodes | Contains query nodes that are commonly used by query parser implementations |
org.apache.lucene.queryParser.core.parser | Contains the necessary interfaces to implement text parsers |
org.apache.lucene.queryParser.core.processors | Interfaces and implementations used by query node processors |
org.apache.lucene.queryParser.core.util | Utility classes to used with the Query Parser |
org.apache.lucene.queryParser.standard | Contains the implementation of the Lucene query parser using the flexible query parser frameworks |
org.apache.lucene.queryParser.standard.builders | Standard Lucene Query Node Builders |
org.apache.lucene.queryParser.standard.config | Standard Lucene Query Configuration |
org.apache.lucene.queryParser.standard.nodes | Standard Lucene Query Nodes |
org.apache.lucene.queryParser.standard.parser | Lucene Query Parser |
org.apache.lucene.queryParser.standard.processors | Lucene Query Node Processors |
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.
It's currently divided in 2 main packages:
org.apache.lucene.queryParser.core
: it contains the query parser API classes, which should be extended by query parser implementations. org.apache.lucene.queryParser.standard
: it contains the current Lucene query parser implementation using the new query parser API.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.
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.
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':
AND / \ A B
The three layers are:
QueryNode
tree. Every text parser
must implement the interface SyntaxParser
.
Lucene default implementations implements it using JavaCC.
QueryNode
types to its specific
builder that will transform the QueryNode into Lucene Query object.
Furthermore, the query parser uses flexible configuration objects, which are based on AttributeSource/Attribute. 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.
This design allows to develop different query syntaxes very quickly.
The standard (default) Lucene query parser is located under org.apache.lucene.queryParser.standard.
To make it simpler to use the new query parser
the class 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.
StandardQueryParser
usage:
StandardQueryParser qpHelper = new StandardQueryParser(); StandardQueryConfigHandler config = qpHelper.getQueryConfigHandler(); config.setAllowLeadingWildcard(true); config.setAnalyzer(new WhitespaceAnalyzer()); Query query = qpHelper.parse("apache AND lucene", "defaultField");
To make it easy for people who are using current Lucene's query parser to switch to
the new one, there is a QueryParserWrapper
under org.apache.lucene.queryParser.standard
that keeps the old query parser interface, but uses the new query parser infrastructure.
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