org.apache.lucene.queryparser.flexible.standard.processors

Class RemoveEmptyNonLeafQueryNodeProcessor

java.lang.Object

org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorImpl

org.apache.lucene.queryparser.flexible.standard.processors.RemoveEmptyNonLeafQueryNodeProcessor

All Implemented Interfaces:

QueryNodeProcessor

public class RemoveEmptyNonLeafQueryNodeProcessor
extends QueryNodeProcessorImpl

This processor removes every QueryNode that is not a leaf and has not children. If after processing the entire tree the root node is not a leaf and has no children, a MatchNoDocsQueryNode object is returned.

This processor is used at the end of a pipeline to avoid invalid query node tree structures like a GroupQueryNode or ModifierQueryNode with no children.

See Also:

QueryNode, MatchNoDocsQueryNode

Constructor Summary

Constructors

Constructor and Description
RemoveEmptyNonLeafQueryNodeProcessor()

Method Summary

Modifier and Type	Method and Description
QueryNode	process(QueryNode queryTree) Processes a query node tree.

Methods inherited from class org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorImpl

getQueryConfigHandler, setQueryConfigHandler

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RemoveEmptyNonLeafQueryNodeProcessor

public RemoveEmptyNonLeafQueryNodeProcessor()

Method Detail

process

public QueryNode process(QueryNode queryTree)
                  throws QueryNodeException

Description copied from interface: QueryNodeProcessor

Processes a query node tree. It may return the same or another query tree. I should never return null.

Specified by:

process in interface QueryNodeProcessor

Overrides:

process in class QueryNodeProcessorImpl

Parameters:

queryTree - tree root node

Returns:

the processed query tree

Throws:

QueryNodeException