org.apache.lucene.queryparser.simple

Class SimpleQueryParser

java.lang.Object

org.apache.lucene.util.QueryBuilder

org.apache.lucene.queryparser.simple.SimpleQueryParser

public class SimpleQueryParser
extends QueryBuilder

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 '\'. 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.

Field Summary

Fields

Modifier and Type	Field and Description
static int	AND_OPERATOR Enables AND operator (+)
static int	ESCAPE_OPERATOR Enables ESCAPE operator (\)
static int	FUZZY_OPERATOR Enables FUZZY operators: (~) on single terms
static int	NEAR_OPERATOR Enables NEAR operators: (~) on phrases
static int	NOT_OPERATOR Enables NOT operator (-)
static int	OR_OPERATOR Enables OR operator (|)
static int	PHRASE_OPERATOR Enables PHRASE operator (")
static int	PRECEDENCE_OPERATORS Enables PRECEDENCE operators: ( and )
static int	PREFIX_OPERATOR Enables PREFIX operator (*)
static int	WHITESPACE_OPERATOR Enables WHITESPACE operators: ' ' '\n' '\r' '\t'

Constructor Summary

Constructors

Constructor and Description
SimpleQueryParser(Analyzer analyzer, Map<String,Float> weights) Creates a new parser searching over multiple fields with different weights.
SimpleQueryParser(Analyzer analyzer, Map<String,Float> weights, int flags) Creates a new parser with custom flags used to enable/disable certain features.
SimpleQueryParser(Analyzer analyzer, String field) Creates a new parser searching over a single field.

Method Summary

Modifier and Type	Method and Description
BooleanClause.Occur	getDefaultOperator() Returns the implicit operator setting, which will be either SHOULD or MUST.
Query	parse(String queryText) Parses the query text and returns parsed query (or null if empty)
void	setDefaultOperator(BooleanClause.Occur operator) Sets the implicit operator setting, which must be either SHOULD or MUST.

Methods inherited from class org.apache.lucene.util.QueryBuilder

createBooleanQuery, createBooleanQuery, createMinShouldMatchQuery, createPhraseQuery, createPhraseQuery, getAnalyzer, getEnablePositionIncrements, setAnalyzer, setEnablePositionIncrements

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

AND_OPERATOR

public static final int AND_OPERATOR

Enables AND operator (+)

See Also:

Constant Field Values

NOT_OPERATOR

public static final int NOT_OPERATOR

Enables NOT operator (-)

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Constant Field Values

OR_OPERATOR

public static final int OR_OPERATOR

Enables OR operator (|)

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Constant Field Values

PREFIX_OPERATOR

public static final int PREFIX_OPERATOR

Enables PREFIX operator (*)

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Constant Field Values

PHRASE_OPERATOR

public static final int PHRASE_OPERATOR

Enables PHRASE operator (")

See Also:

Constant Field Values

PRECEDENCE_OPERATORS

public static final int PRECEDENCE_OPERATORS

Enables PRECEDENCE operators: ( and )

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Constant Field Values

ESCAPE_OPERATOR

public static final int ESCAPE_OPERATOR

Enables ESCAPE operator (\)

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Constant Field Values

WHITESPACE_OPERATOR

public static final int WHITESPACE_OPERATOR

Enables WHITESPACE operators: ' ' '\n' '\r' '\t'

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Constant Field Values

FUZZY_OPERATOR

public static final int FUZZY_OPERATOR

Enables FUZZY operators: (~) on single terms

See Also:

Constant Field Values

NEAR_OPERATOR

public static final int NEAR_OPERATOR

Enables NEAR operators: (~) on phrases

See Also:

Constant Field Values

Constructor Detail

SimpleQueryParser

public SimpleQueryParser(Analyzer analyzer,
                         String field)

Creates a new parser searching over a single field.

SimpleQueryParser

public SimpleQueryParser(Analyzer analyzer,
                         Map<String,Float> weights)

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

SimpleQueryParser

public SimpleQueryParser(Analyzer analyzer,
                         Map<String,Float> weights,
                         int flags)

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

Method Detail

parse

public Query parse(String queryText)

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

getDefaultOperator

public BooleanClause.Occur getDefaultOperator()

Returns the implicit operator setting, which will be either SHOULD or MUST.

setDefaultOperator

public void setDefaultOperator(BooleanClause.Occur operator)

Sets the implicit operator setting, which must be either SHOULD or MUST.