org.apache.lucene.queryParser.core.processors
Class QueryNodeProcessorImpl

java.lang.Object
  extended by org.apache.lucene.queryParser.core.processors.QueryNodeProcessorImpl
All Implemented Interfaces:
QueryNodeProcessor
Direct Known Subclasses:
AllowLeadingWildcardProcessor, AnalyzerQueryNodeProcessor, BooleanSingleChildOptimizationQueryNodeProcessor, BoostQueryNodeProcessor, DefaultPhraseSlopQueryNodeProcessor, FuzzyQueryNodeProcessor, LowercaseExpandedTermsQueryNodeProcessor, MatchAllDocsQueryNodeProcessor, MultiFieldQueryNodeProcessor, MultiTermRewriteMethodProcessor, NoChildOptimizationQueryNodeProcessor, ParametricRangeQueryNodeProcessor, PhraseSlopQueryNodeProcessor, RemoveDeletedQueryNodesProcessor, RemoveEmptyNonLeafQueryNodeProcessor, 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
QueryNodeProcessorImpl()
           
QueryNodeProcessorImpl(QueryConfigHandler queryConfigHandler)
           
 
Method Summary
 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


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