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Query nodes commonly used by query parser implementations.

## Query Nodes

 The package <tt>org.apache.lucene.queryParser.nodes</tt> contains all the basic query nodes. The interface that represents a query node is <xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode>. 

 <xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode>s are used by the text parser to create a syntax tree. These nodes are designed to be used by UI or other text parsers. The default Lucene text parser is <xref:Lucene.Net.QueryParsers.Flexible.Standard.Parser.StandardSyntaxParser>, it implements Lucene's standard syntax. 

 <xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode> interface should be implemented by all query nodes, the class <xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNodeImpl> implements <xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode> and is extended by all current query node implementations. 

 A query node tree can be printed to the a stream, and it generates a pseudo XML representation with all the nodes. 

 A query node tree can also generate a query string that can be parsed back by the original text parser, at this point only the standard lucene syntax is supported. 

 Grouping nodes: * AndQueryNode - used for AND operator * AnyQueryNode - used for ANY operator * OrQueryNode - used for OR operator * BooleanQueryNode - used when no operator is specified * ModifierQueryNode - used for modifier operator * GroupQueryNode - used for parenthesis * BoostQueryNode - used for boost operator * SlopQueryNode - phrase slop * FuzzyQueryNode - fuzzy node * TermRangeQueryNode - used for parametric field:[low_value TO high_value] * ProximityQueryNode - used for proximity search * NumericRangeQueryNode - used for numeric range search * TokenizedPhraseQueryNode - used by tokenizers/lemmatizers/analyzers for phrases/autophrases 

 Leaf Nodes: * FieldQueryNode - field/value node * NumericQueryNode - used for numeric search * PathQueryNode - <xref:Lucene.Net.QueryParsers.Flexible.Core.Nodes.QueryNode> object used with path-like queries * OpaqueQueryNode - Used as for part of the query that can be parsed by other parsers. schema/value * PrefixWildcardQueryNode - non-phrase wildcard query * QuotedFieldQUeryNode - regular phrase node * WildcardQueryNode - non-phrase wildcard query 

 Utility Nodes: * DeletedQueryNode - used by processors on optimizations * MatchAllDocsQueryNode - used by processors on optimizations * MatchNoDocsQueryNode - used by processors on optimizations * NoTokenFoundQueryNode - used by tokenizers/lemmatizers/analyzers 