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 OR token1 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 '</code>'. The following characters will need to be escaped in terms and phrases: + | " ( ) ' </code>

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

Note that above examples consider the terms before text processing.

Inheritance

System.Object

SimpleQueryParser

Namespace: Lucene.Net.QueryParsers.Simple

Assembly: Lucene.Net.QueryParser.dll

Syntax

public class SimpleQueryParser : QueryBuilder

Constructors

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SimpleQueryParser(Analyzer, IDictionary<String, Single>)

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<System.String, System.Single>	weights

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SimpleQueryParser(Analyzer, IDictionary<String, Single>, 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<System.String, System.Single>	weights
Operator	flags

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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
System.String	field

Fields

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m_flags

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

Declaration

protected readonly Operator m_flags

Field Value

Type	Description
Operator

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m_weights

Map of fields to query against with their weights

Declaration

protected readonly IDictionary<string, float> m_weights

Field Value

Type	Description
IDictionary<System.String, System.Single>

Properties

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DefaultOperator

Gets or Sets the implicit operator setting, which will be either or .

Declaration

public virtual Occur DefaultOperator { get; set; }

Property Value

Type	Description
Occur

Methods

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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
System.String	text

Returns

Type	Description
Query

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NewFuzzyQuery(String, Int32)

Factory method to generate a fuzzy query.

Declaration

protected virtual Query NewFuzzyQuery(string text, int fuzziness)

Parameters

Type	Name	Description
System.String	text
System.Int32	fuzziness

Returns

Type	Description
Query

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NewPhraseQuery(String, Int32)

Factory method to generate a phrase query with slop.

Declaration

protected virtual Query NewPhraseQuery(string text, int slop)

Parameters

Type	Name	Description
System.String	text
System.Int32	slop

Returns

Type	Description
Query

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NewPrefixQuery(String)

Factory method to generate a prefix query.

Declaration

protected virtual Query NewPrefixQuery(string text)

Parameters

Type	Name	Description
System.String	text

Returns

Type	Description
Query

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Parse(String)

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

Declaration

public Query Parse(string queryText)

Parameters

Type	Name	Description
System.String	queryText

Returns

Type	Description
Query

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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