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

Class QueryNodeProcessorImpl

java.lang.Object

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

All Implemented Interfaces:

QueryNodeProcessor

Direct Known Subclasses:

AllowLeadingWildcardProcessor, AnalyzerQueryNodeProcessor, BooleanModifiersQueryNodeProcessor, BooleanSingleChildOptimizationQueryNodeProcessor, BoostQueryNodeProcessor, DefaultPhraseSlopQueryNodeProcessor, FuzzyQueryNodeProcessor, MatchAllDocsQueryNodeProcessor, MultiFieldQueryNodeProcessor, MultiTermRewriteMethodProcessor, NoChildOptimizationQueryNodeProcessor, OpenRangeQueryNodeProcessor, PhraseSlopQueryNodeProcessor, PointQueryNodeProcessor, PointRangeQueryNodeProcessor, RegexpQueryNodeProcessor, RemoveDeletedQueryNodesProcessor, RemoveEmptyNonLeafQueryNodeProcessor, TermRangeQueryNodeProcessor, WildcardQueryNodeProcessor

public abstract class QueryNodeProcessorImpl
extends Object
implements QueryNodeProcessor

This is a default implementation for the QueryNodeProcessor interface, it's an abstract class, so it should be extended by classes that want to process a QueryNode tree.

This class process QueryNodes from left to right in the tree. While it's walking down the tree, for every node, preProcessNode(QueryNode) is invoked. After a node's children are processed, postProcessNode(QueryNode) is invoked for that node. setChildrenOrder(List) is invoked before postProcessNode(QueryNode) only if the node has at least one child, in setChildrenOrder(List) the implementor might redefine the children order or remove any children from the children list.

Here is an example about how it process the nodes:

      a
     / \
    b   e
   / \
  c   d
 

Here is the order the methods would be invoked for the tree described above:

      preProcessNode( a );
      preProcessNode( b );
      preProcessNode( c );
      postProcessNode( c );
      preProcessNode( d );
      postProcessNode( d );
      setChildrenOrder( bChildrenList );
      postProcessNode( b );
      preProcessNode( e );
      postProcessNode( e );
      setChildrenOrder( aChildrenList );
      postProcessNode( a )
 

See Also:

QueryNodeProcessor

Constructor Summary

Constructors

Constructor and Description
QueryNodeProcessorImpl()
QueryNodeProcessorImpl(QueryConfigHandler queryConfigHandler)

Method Summary

Modifier and Type	Method and Description
QueryConfigHandler	getQueryConfigHandler() For reference about this method check: QueryNodeProcessor.getQueryConfigHandler().
protected abstract QueryNode	postProcessNode(QueryNode node) This method is invoked for every node when walking up the tree.
protected abstract QueryNode	preProcessNode(QueryNode node) This method is invoked for every node when walking down the tree.
QueryNode	process(QueryNode queryTree) Processes a query node tree.
protected void	processChildren(QueryNode queryTree) This method is called every time a child is processed.
protected abstract List<QueryNode>	setChildrenOrder(List<QueryNode> children) This method is invoked for every node that has at least on child.
void	setQueryConfigHandler(QueryConfigHandler queryConfigHandler) For reference about this method check: QueryNodeProcessor.setQueryConfigHandler(QueryConfigHandler).

Methods inherited from class java.lang.Object

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

Constructor Detail

QueryNodeProcessorImpl

public QueryNodeProcessorImpl()

QueryNodeProcessorImpl

public QueryNodeProcessorImpl(QueryConfigHandler queryConfigHandler)

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

Parameters:

queryTree - tree root node

Returns:

the processed query tree

Throws:

QueryNodeException

processChildren

protected void processChildren(QueryNode queryTree)
                        throws QueryNodeException

This method is called every time a child is processed.

Parameters:

queryTree - the query node child to be processed

Throws:

QueryNodeException - if something goes wrong during the query node processing

setQueryConfigHandler

public void setQueryConfigHandler(QueryConfigHandler queryConfigHandler)

For reference about this method check: QueryNodeProcessor.setQueryConfigHandler(QueryConfigHandler).

Specified by:

setQueryConfigHandler in interface QueryNodeProcessor

Parameters:

queryConfigHandler - the query configuration handler to be set.

See Also:

QueryNodeProcessor.getQueryConfigHandler(), QueryConfigHandler

getQueryConfigHandler

public QueryConfigHandler getQueryConfigHandler()

For reference about this method check: QueryNodeProcessor.getQueryConfigHandler().

Specified by:

getQueryConfigHandler in interface QueryNodeProcessor

Returns:

QueryConfigHandler the query configuration handler to be set.

See Also:

QueryNodeProcessor.setQueryConfigHandler(QueryConfigHandler), QueryConfigHandler

preProcessNode

protected abstract QueryNode preProcessNode(QueryNode node)
                                     throws QueryNodeException

This method is invoked for every node when walking down the tree.

Parameters:

node - the query node to be pre-processed

Returns:

a query node

Throws:

QueryNodeException - if something goes wrong during the query node processing

postProcessNode

protected abstract QueryNode postProcessNode(QueryNode node)
                                      throws QueryNodeException

This method is invoked for every node when walking up the tree.

Parameters:

node - node the query node to be post-processed

Returns:

a query node

Throws:

QueryNodeException - if something goes wrong during the query node processing

setChildrenOrder

protected abstract List<QueryNode> setChildrenOrder(List<QueryNode> children)
                                             throws QueryNodeException

This method is invoked for every node that has at least on child. It's invoked right before postProcessNode(QueryNode) is invoked.

Parameters:

children - the list containing all current node's children

Returns:

a new list containing all children that should be set to the current node

Throws:

QueryNodeException - if something goes wrong during the query node processing