org.apache.lucene.queryParser.precedence
Class PrecedenceQueryParser

java.lang.Object
  org.apache.lucene.queryParser.precedence.PrecedenceQueryParser

All Implemented Interfaces:

PrecedenceQueryParserConstants

public class PrecedenceQueryParser
extends Object
implements PrecedenceQueryParserConstants

Experimental query parser variant designed to handle operator precedence in a more sensible fashion than QueryParser. There are still some open issues with this parser. The following tests are currently failing in TestPrecedenceQueryParser and are disabled to make this test pass:

• testSimple
• testWildcard
• testPrecedence

This class is generated by JavaCC. The only method that clients should need to call is parse(String). The syntax for query strings is as follows: A Query is a series of clauses. A clause may be prefixed by:

• a plus (+) or a minus (-) sign, indicating that the clause is required or prohibited respectively; or
• a term followed by a colon, indicating the field to be searched. This enables one to construct queries which search multiple fields.

A clause may be either:

• a term, indicating all the documents that contain this term; or
• a nested query, enclosed in parentheses. Note that this may be used with a +/- prefix to require any of a set of terms.

Thus, in BNF, the query grammar is:

   Query  ::= ( Clause )*
   Clause ::= ["+", "-"] [<TERM> ":"] ( <TERM> | "(" Query ")" )
 

Examples of appropriately formatted queries can be found in the query syntax documentation.

Author:

Brian Goetz, Peter Halacsy, Tatu Saloranta

Field Summary

static org.apache.lucene.queryParser.precedence.PrecedenceQueryParser.Operator	AND_OPERATOR
Token	jj_nt
boolean	lookingAhead
static org.apache.lucene.queryParser.precedence.PrecedenceQueryParser.Operator	OR_OPERATOR
Token	token
PrecedenceQueryParserTokenManager	token_source

Fields inherited from interface org.apache.lucene.queryParser.precedence.PrecedenceQueryParserConstants

_ESCAPED_CHAR, _NUM_CHAR, _TERM_CHAR, _TERM_START_CHAR, _WHITESPACE, AND, Boost, CARAT, COLON, DEFAULT, EOF, FUZZY_SLOP, LPAREN, MINUS, NOT, NUMBER, OR, PLUS, PREFIXTERM, QUOTED, RangeEx, RANGEEX_END, RANGEEX_GOOP, RANGEEX_QUOTED, RANGEEX_START, RANGEEX_TO, RangeIn, RANGEIN_END, RANGEIN_GOOP, RANGEIN_QUOTED, RANGEIN_START, RANGEIN_TO, RPAREN, TERM, tokenImage, WILDTERM

Constructor Summary

PrecedenceQueryParser(CharStream stream)

PrecedenceQueryParser(PrecedenceQueryParserTokenManager tm)

PrecedenceQueryParser(String f, Analyzer a)
Constructs a query parser.

Method Summary

protected void	addClause(Vector clauses, int conj, int modifier, Query q)
Query	andExpression(String field)
Query	Clause(String field)
int	Conjunction()
void	disable_tracing()
void	enable_tracing()
static String	escape(String s) Returns a String where those characters that QueryParser expects to be escaped are escaped by a preceding \.
ParseException	generateParseException()
Analyzer	getAnalyzer()
protected Query	getBooleanQuery(Vector clauses) Factory method for generating query, given a set of clauses.
protected Query	getBooleanQuery(Vector clauses, boolean disableCoord) Factory method for generating query, given a set of clauses.
org.apache.lucene.queryParser.precedence.PrecedenceQueryParser.Operator	getDefaultOperator() Gets implicit operator setting, which will be either AND_OPERATOR or OR_OPERATOR.
String	getField()
protected Query	getFieldQuery(String field, String queryText)
protected Query	getFieldQuery(String field, String queryText, int slop) Base implementation delegates to getFieldQuery(String,String).
float	getFuzzyMinSim() Get the minimal similarity for fuzzy queries.
int	getFuzzyPrefixLength() Get the prefix length for fuzzy queries.
protected Query	getFuzzyQuery(String field, String termStr, float minSimilarity) Factory method for generating a query (similar to getWildcardQuery(java.lang.String, java.lang.String)).
Locale	getLocale() Returns current locale, allowing access by subclasses.
boolean	getLowercaseExpandedTerms()
Token	getNextToken()
int	getPhraseSlop() Gets the default slop for phrases.
protected Query	getPrefixQuery(String field, String termStr) Factory method for generating a query (similar to getWildcardQuery(java.lang.String, java.lang.String)).
protected Query	getRangeQuery(String field, String part1, String part2, boolean inclusive)
Token	getToken(int index)
protected Query	getWildcardQuery(String field, String termStr) Factory method for generating a query.
static void	main(String[] args) Command line tool to test QueryParser, using SimpleAnalyzer.
int	Modifier()
Query	parse(String expression) Parses a query string, returning a Query.
Query	Query(String field)
void	ReInit(CharStream stream)
void	ReInit(PrecedenceQueryParserTokenManager tm)
void	setDefaultOperator(org.apache.lucene.queryParser.precedence.PrecedenceQueryParser.Operator op) Sets the boolean operator of the QueryParser.
void	setFuzzyMinSim(float fuzzyMinSim) Set the minimum similarity for fuzzy queries.
void	setFuzzyPrefixLength(int fuzzyPrefixLength) Set the prefix length for fuzzy queries.
void	setLocale(Locale locale) Set locale used by date range parsing.
void	setLowercaseExpandedTerms(boolean lowercaseExpandedTerms) Whether terms of wildcard, prefix, fuzzy and range queries are to be automatically lower-cased or not.
void	setPhraseSlop(int phraseSlop) Sets the default slop for phrases.
Query	Term(String field)

Methods inherited from class java.lang.Object

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

Field Detail

AND_OPERATOR

public static final org.apache.lucene.queryParser.precedence.PrecedenceQueryParser.Operator AND_OPERATOR

OR_OPERATOR

public static final org.apache.lucene.queryParser.precedence.PrecedenceQueryParser.Operator OR_OPERATOR

token_source

public PrecedenceQueryParserTokenManager token_source

token

public Token token

jj_nt

public Token jj_nt

lookingAhead

public boolean lookingAhead

Constructor Detail

PrecedenceQueryParser

public PrecedenceQueryParser(String f,
                             Analyzer a)

Constructs a query parser.

Parameters:

f - the default field for query terms.

a - used to find terms in the query text.

PrecedenceQueryParser

public PrecedenceQueryParser(CharStream stream)

PrecedenceQueryParser

public PrecedenceQueryParser(PrecedenceQueryParserTokenManager tm)

Method Detail

parse

public Query parse(String expression)
            throws ParseException

Parses a query string, returning a Query.

Parameters:

expression - the query string to be parsed.

Throws:

ParseException - if the parsing fails

getAnalyzer

public Analyzer getAnalyzer()

Returns:

Returns the analyzer.

getField

public String getField()

Returns:

Returns the field.

getFuzzyMinSim

public float getFuzzyMinSim()

Get the minimal similarity for fuzzy queries.

setFuzzyMinSim

public void setFuzzyMinSim(float fuzzyMinSim)

Set the minimum similarity for fuzzy queries. Default is 0.5f.

getFuzzyPrefixLength

public int getFuzzyPrefixLength()

Get the prefix length for fuzzy queries.

Returns:

Returns the fuzzyPrefixLength.

setFuzzyPrefixLength

public void setFuzzyPrefixLength(int fuzzyPrefixLength)

Set the prefix length for fuzzy queries. Default is 0.

Parameters:

fuzzyPrefixLength - The fuzzyPrefixLength to set.

setPhraseSlop

public void setPhraseSlop(int phraseSlop)

Sets the default slop for phrases. If zero, then exact phrase matches are required. Default value is zero.

getPhraseSlop

public int getPhraseSlop()

Gets the default slop for phrases.

setDefaultOperator

public void setDefaultOperator(org.apache.lucene.queryParser.precedence.PrecedenceQueryParser.Operator op)

Sets the boolean operator of the QueryParser. In default mode (OR_OPERATOR) terms without any modifiers are considered optional: for example capital of Hungary is equal to capital OR of OR Hungary.
In AND_OPERATOR mode terms are considered to be in conjuction: the above mentioned query is parsed as capital AND of AND Hungary

getDefaultOperator

public org.apache.lucene.queryParser.precedence.PrecedenceQueryParser.Operator getDefaultOperator()

Gets implicit operator setting, which will be either AND_OPERATOR or OR_OPERATOR.

setLowercaseExpandedTerms

public void setLowercaseExpandedTerms(boolean lowercaseExpandedTerms)

Whether terms of wildcard, prefix, fuzzy and range queries are to be automatically lower-cased or not. Default is true.

getLowercaseExpandedTerms

public boolean getLowercaseExpandedTerms()

See Also:

setLowercaseExpandedTerms(boolean)

setLocale

public void setLocale(Locale locale)

Set locale used by date range parsing.

getLocale

public Locale getLocale()

Returns current locale, allowing access by subclasses.

addClause

protected void addClause(Vector clauses,
                         int conj,
                         int modifier,
                         Query q)

getFieldQuery

protected Query getFieldQuery(String field,
                              String queryText)
                       throws ParseException

Throws:

ParseException - throw in overridden method to disallow

getFieldQuery

protected Query getFieldQuery(String field,
                              String queryText,
                              int slop)
                       throws ParseException

Base implementation delegates to getFieldQuery(String,String). This method may be overridden, for example, to return a SpanNearQuery instead of a PhraseQuery.

Throws:

ParseException - throw in overridden method to disallow

getRangeQuery

protected Query getRangeQuery(String field,
                              String part1,
                              String part2,
                              boolean inclusive)
                       throws ParseException

Throws:

ParseException - throw in overridden method to disallow

getBooleanQuery

protected Query getBooleanQuery(Vector clauses)
                         throws ParseException

Factory method for generating query, given a set of clauses. By default creates a boolean query composed of clauses passed in. Can be overridden by extending classes, to modify query being returned.

Parameters:

clauses - Vector that contains BooleanClause instances to join.

Returns:

Resulting Query object.

Throws:

ParseException - throw in overridden method to disallow

getBooleanQuery

protected Query getBooleanQuery(Vector clauses,
                                boolean disableCoord)
                         throws ParseException

Factory method for generating query, given a set of clauses. By default creates a boolean query composed of clauses passed in. Can be overridden by extending classes, to modify query being returned.

Parameters:

clauses - Vector that contains BooleanClause instances to join.

disableCoord - true if coord scoring should be disabled.

Returns:

Resulting Query object.

Throws:

ParseException - throw in overridden method to disallow

getWildcardQuery

protected Query getWildcardQuery(String field,
                                 String termStr)
                          throws ParseException

Factory method for generating a query. Called when parser parses an input term token that contains one or more wildcard characters (? and *), but is not a prefix term token (one that has just a single * character at the end)

Depending on settings, prefix term may be lower-cased automatically. It will not go through the default Analyzer, however, since normal Analyzers are unlikely to work properly with wildcard templates.

Can be overridden by extending classes, to provide custom handling for wildcard queries, which may be necessary due to missing analyzer calls.

Parameters:

field - Name of the field query will use.

termStr - Term token that contains one or more wild card characters (? or *), but is not simple prefix term

Returns:

Resulting Query built for the term

Throws:

ParseException - throw in overridden method to disallow

getPrefixQuery

protected Query getPrefixQuery(String field,
                               String termStr)
                        throws ParseException

Factory method for generating a query (similar to getWildcardQuery(java.lang.String, java.lang.String)). Called when parser parses an input term token that uses prefix notation; that is, contains a single '*' wildcard character as its last character. Since this is a special case of generic wildcard term, and such a query can be optimized easily, this usually results in a different query object.

Depending on settings, a prefix term may be lower-cased automatically. It will not go through the default Analyzer, however, since normal Analyzers are unlikely to work properly with wildcard templates.

Can be overridden by extending classes, to provide custom handling for wild card queries, which may be necessary due to missing analyzer calls.

Parameters:

field - Name of the field query will use.

termStr - Term token to use for building term for the query (without trailing '*' character!)

Returns:

Resulting Query built for the term

Throws:

ParseException - throw in overridden method to disallow

getFuzzyQuery

protected Query getFuzzyQuery(String field,
                              String termStr,
                              float minSimilarity)
                       throws ParseException

Factory method for generating a query (similar to getWildcardQuery(java.lang.String, java.lang.String)). Called when parser parses an input term token that has the fuzzy suffix (~) appended.

Parameters:

field - Name of the field query will use.

termStr - Term token to use for building term for the query

Returns:

Resulting Query built for the term

Throws:

ParseException - throw in overridden method to disallow

escape

public static String escape(String s)

Returns a String where those characters that QueryParser expects to be escaped are escaped by a preceding \.

main

public static void main(String[] args)
                 throws Exception

Command line tool to test QueryParser, using SimpleAnalyzer. Usage:
java org.apache.lucene.queryParser.QueryParser <input>

Throws:

Exception

Conjunction

public final int Conjunction()
                      throws ParseException

Throws:

ParseException

Modifier

public final int Modifier()
                   throws ParseException

Throws:

ParseException

Query

public final Query Query(String field)
                  throws ParseException

Throws:

ParseException

andExpression

public final Query andExpression(String field)
                          throws ParseException

Throws:

ParseException

Clause

public final Query Clause(String field)
                   throws ParseException

Throws:

ParseException

Term

public final Query Term(String field)
                 throws ParseException

Throws:

ParseException

ReInit

public void ReInit(CharStream stream)

ReInit

public void ReInit(PrecedenceQueryParserTokenManager tm)

getNextToken

public final Token getNextToken()

getToken

public final Token getToken(int index)

generateParseException

public ParseException generateParseException()

enable_tracing

public final void enable_tracing()

disable_tracing

public final void disable_tracing()