Class SimpleQueryParser

SimpleQueryParser is used to parse human readable query syntax.

The main idea behind this parser is that a person should be able to type whatever they want to represent a query, and this parser will do its best to interpret what to search for no matter how poorly composed the request may be. Tokens are considered to be any of a term, phrase, or subquery for the operations described below. Whitespace including ' ' '\n' '\r' and '\t' and certain operators may be used to delimit tokens ( ) + | " .

Any errors in query syntax will be ignored and the parser will attempt to decipher what it can; however, this may mean odd or unexpected results.

Query Operators

'+' specifies AND operation: token1+token2
'|' specifies OR operation: token1|token2
'-' negates a single token: -token0
'"' creates phrases of terms: "term1 term2 ..."
'*' at the end of terms specifies prefix query: term*
'~N' at the end of terms specifies fuzzy query: term~1
'~N' at the end of phrases specifies near query: "term1 term2"~5
'(' and ')' specifies precedence: token1 + (token2 | token3)

The default operator is OR if no other operator is specified. For example, the following will ORtoken1 and token2 together: token1 token2

Normal operator precedence will be simple order from right to left. For example, the following will evaluate token1 OR token2 first, then AND with token3:

token1 | token2 + token3

Escaping

An individual term may contain any possible character with certain characters requiring escaping using a '\'. The following characters will need to be escaped in terms and phrases: + | " ( ) ' \

The '-' operator is a special case. On individual terms (not phrases) the first character of a term that is - must be escaped; however, any '-' characters beyond the first character do not need to be escaped. For example:

-term1 -- Specifies NOT operation against term1
\-term1 -- Searches for the term -term1.
term-1 -- Searches for the term term-1.
term\-1 -- Searches for the term term-1.

The '*' operator is a special case. On individual terms (not phrases) the last character of a term that is '*' must be escaped; however, any '*' characters before the last character do not need to be escaped:

term1* -- Searches for the prefix term1
term1\* -- Searches for the term term1*
term*1 -- Searches for the term term*1
term\*1 -- Searches for the term term*1

Note that above examples consider the terms before text processing.

Inheritance

object

QueryBuilder

SimpleQueryParser

Inherited Members

QueryBuilder.CreateBooleanQuery(string, string)

QueryBuilder.CreateBooleanQuery(string, string, Occur)

QueryBuilder.CreatePhraseQuery(string, string)

QueryBuilder.CreatePhraseQuery(string, string, int)

QueryBuilder.CreateMinShouldMatchQuery(string, string, float)

QueryBuilder.Analyzer

QueryBuilder.EnablePositionIncrements

QueryBuilder.CreateFieldQuery(Analyzer, Occur, string, string, bool, int)

QueryBuilder.NewBooleanQuery(bool)

QueryBuilder.NewTermQuery(Term)

QueryBuilder.NewPhraseQuery()

QueryBuilder.NewMultiPhraseQuery()

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Lucene.Net.QueryParsers.Simple

Assembly: Lucene.Net.QueryParser.dll

Syntax

public class SimpleQueryParser : QueryBuilder

Constructors

SimpleQueryParser(Analyzer, IDictionary<string, float>)

Creates a new parser searching over multiple fields with different weights.

Declaration

public SimpleQueryParser(Analyzer analyzer, IDictionary<string, float> weights)

Parameters

Type	Name	Description
Analyzer	analyzer
IDictionary<string, float>	weights

SimpleQueryParser(Analyzer, IDictionary<string, float>, Operator)

Creates a new parser with custom flags used to enable/disable certain features.

Declaration

public SimpleQueryParser(Analyzer analyzer, IDictionary<string, float> weights, Operator flags)

Parameters

Type	Name	Description
Analyzer	analyzer
IDictionary<string, float>	weights
Operator	flags

SimpleQueryParser(Analyzer, string)

Creates a new parser searching over a single field.

Declaration

public SimpleQueryParser(Analyzer analyzer, string field)

Parameters

Type	Name	Description
Analyzer	analyzer
string	field

Fields

m_flags

flags to the parser (to turn features on/off)

Declaration

protected readonly Operator m_flags

Field Value

Type	Description
Operator

m_weights

Map of fields to query against with their weights

Declaration

protected readonly IDictionary<string, float> m_weights

Field Value

Type	Description
IDictionary<string, float>

Properties

DefaultOperator

Gets or Sets the implicit operator setting, which will be either Lucene.Net.Search.Occur.SHOULD or Lucene.Net.Search.Occur.MUST.

Declaration

public virtual Occur DefaultOperator { get; set; }

Property Value

Type	Description
Occur

Methods

NewDefaultQuery(string)

Factory method to generate a standard query (no phrase or prefix operators).

Declaration

protected virtual Query NewDefaultQuery(string text)

Parameters

Type	Name	Description
string	text

Returns

Type	Description
Query

NewFuzzyQuery(string, int)

Factory method to generate a fuzzy query.

Declaration

protected virtual Query NewFuzzyQuery(string text, int fuzziness)

Parameters

Type	Name	Description
string	text
int	fuzziness

Returns

Type	Description
Query

NewPhraseQuery(string, int)

Factory method to generate a phrase query with slop.

Declaration

protected virtual Query NewPhraseQuery(string text, int slop)

Parameters

Type	Name	Description
string	text
int	slop

Returns

Type	Description
Query

NewPrefixQuery(string)

Factory method to generate a prefix query.

Declaration

protected virtual Query NewPrefixQuery(string text)

Parameters

Type	Name	Description
string	text

Returns

Type	Description
Query

Parse(string)

Parses the query text and returns parsed query (or null if empty)

Declaration

public Query Parse(string queryText)

Parameters

Type	Name	Description
string	queryText

Returns

Type	Description
Query

Simplify(BooleanQuery)

Helper to simplify boolean queries with 0 or 1 clause

Declaration

protected virtual Query Simplify(BooleanQuery bq)

Parameters

Type	Name	Description
BooleanQuery	bq

Returns

Type	Description
Query