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Interfaces and implementations used by query node processors

## Query Node Processors

 The package <tt>org.apache.lucene.queryParser.processors</tt> contains interfaces that should be implemented by every query node processor. 

 The interface that every query node processor should implement is [](xref:Lucene.Net.QueryParsers.Flexible.Core.Processors.QueryNodeProcessor). 

 A query node processor should be used to process a [](xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode) tree. [](xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode) trees can be programmatically created or generated by a text parser. See [](xref:Lucene.Net.QueryParsers.Flexible.Core.Parser) for more details about text parsers. 

 A query node processor should be used to process a [](xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode) tree. [](xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode) trees can be programmatically created or generated by a text parser. See [](xref:Lucene.Net.QueryParsers.Flexible.Core.Parser) for more details about text parsers. 

 A pipeline of processors can be assembled using [](xref:Lucene.Net.QueryParsers.Flexible.Core.Processors.QueryNodeProcessorPipeline). 

 Implementors may want to extend [](xref:Lucene.Net.QueryParsers.Flexible.Core.Processors.QueryNodeProcessorImpl), which simplifies the implementation, because it walks automatically the [](xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode). See [](xref:Lucene.Net.QueryParsers.Flexible.Core.Processors.QueryNodeProcessorImpl) for more details. 