Build a Xapian::Query object from a user query string. More...

#include <queryparser.h>

Public Types
enum	feature_flag { FLAG_BOOLEAN = 1 , FLAG_PHRASE = 2 , FLAG_LOVEHATE = 4 , FLAG_BOOLEAN_ANY_CASE = 8 , FLAG_WILDCARD = 16 , FLAG_PURE_NOT = 32 , FLAG_PARTIAL = 64 , FLAG_SPELLING_CORRECTION = 128 , FLAG_SYNONYM = 256 , FLAG_AUTO_SYNONYMS = 512 , FLAG_AUTO_MULTIWORD_SYNONYMS = 1024 , FLAG_NGRAMS = 2048 , FLAG_CJK_NGRAM = FLAG_NGRAMS , FLAG_ACCUMULATE = 65536 , FLAG_NO_POSITIONS = 0x20000 , FLAG_DEFAULT = FLAG_PHRASE\|FLAG_BOOLEAN\|FLAG_LOVEHATE }
	Enum of feature flags. More...

enum	stem_strategy { STEM_NONE , STEM_SOME , STEM_ALL , STEM_ALL_Z , STEM_SOME_FULL_POS }
	Stemming strategies, for use with set_stemming_strategy().

Public Member Functions
	QueryParser (const QueryParser &o)
	Copy constructor.

QueryParser &	operator= (const QueryParser &o)
	Assignment.

	QueryParser ()
	Default constructor.

	~QueryParser ()
	Destructor.

void	set_stemmer (const Xapian::Stem &stemmer)
	Set the stemmer.

void	set_stemming_strategy (stem_strategy strategy)
	Set the stemming strategy.

void	set_stopper (const Stopper *stop=NULL)
	Set the stopper.

void	set_default_op (Query::op default_op)
	Set the default operator.

Query::op	get_default_op () const
	Get the current default operator.

void	set_database (const Database &db)
	Specify the database being searched.

void	set_max_expansion (Xapian::termcount max_expansion, int max_type=Xapian::Query::WILDCARD_LIMIT_ERROR, unsigned flags=FLAG_WILDCARD\|FLAG_PARTIAL)
	Specify the maximum expansion of a wildcard and/or partial term.

void	set_max_wildcard_expansion (Xapian::termcount)
	Specify the maximum expansion of a wildcard.

Query	parse_query (const std::string &query_string, unsigned flags=FLAG_DEFAULT, const std::string &default_prefix=std::string())
	Parse a query.

void	add_prefix (const std::string &field, const std::string &prefix)
	Add a free-text field term prefix.

void	add_prefix (const std::string &field, Xapian::FieldProcessor *proc)
	Register a FieldProcessor.

void	add_boolean_prefix (const std::string &field, const std::string &prefix, const std::string *grouping=NULL)
	Add a boolean term prefix allowing the user to restrict a search with a boolean filter specified in the free text query.

void	add_boolean_prefix (const std::string &field, const std::string &prefix, bool exclusive)
	Add a boolean term prefix allowing the user to restrict a search with a boolean filter specified in the free text query.

void	add_boolean_prefix (const std::string &field, Xapian::FieldProcessor proc, const std::string grouping=NULL)
	Register a FieldProcessor for a boolean prefix.

void	add_boolean_prefix (const std::string &field, Xapian::FieldProcessor *proc, bool exclusive)
	Register a FieldProcessor for a boolean prefix.

TermIterator	stoplist_begin () const
	Begin iterator over terms omitted from the query as stopwords.

TermIterator	stoplist_end () const
	End iterator over terms omitted from the query as stopwords.

TermIterator	unstem_begin (const std::string &term) const
	Begin iterator over unstemmed forms of the given stemmed query term.

TermIterator	unstem_end (const std::string &) const
	End iterator over unstemmed forms of the given stemmed query term.

void	add_rangeprocessor (Xapian::RangeProcessor range_proc, const std::string grouping=NULL)
	Register a RangeProcessor.

void	add_valuerangeprocessor (Xapian::ValueRangeProcessor *vrproc)
	Register a ValueRangeProcessor.

std::string	get_corrected_query_string () const
	Get the spelling-corrected query string.

std::string	get_description () const
	Return a string describing this object.

Detailed Description

Build a Xapian::Query object from a user query string.

Member Enumeration Documentation

◆ feature_flag

enum Xapian::QueryParser::feature_flag

Enum of feature flags.

Enumerator
FLAG_BOOLEAN	Support AND, OR, etc and bracketed subexpressions.
FLAG_PHRASE	Support quoted phrases.
FLAG_LOVEHATE	Support + and -.
FLAG_BOOLEAN_ANY_CASE	Support AND, OR, etc even if they aren't in ALLCAPS.
FLAG_WILDCARD	Support wildcards. At present only right truncation (e.g. Xap*) is supported. Currently you can't use wildcards with boolean filter prefixes, or in a phrase (either an explicitly quoted one, or one implicitly generated by hyphens or other punctuation). In Xapian 1.2.x, you needed to tell the QueryParser object which database to expand wildcards from by calling set_database(). In Xapian 1.3.3, OP_WILDCARD was added and wildcards are now expanded when Enquire::get_mset() is called, with the expansion using the database being searched.
FLAG_PURE_NOT	Allow queries such as 'NOT apples'. These require the use of a list of all documents in the database which is potentially expensive, so this feature isn't enabled by default.
FLAG_PARTIAL	Enable partial matching. Partial matching causes the parser to treat the query as a "partially entered" search. This will automatically treat the final word as a wildcarded match, unless it is followed by whitespace, to produce more stable results from interactive searches. Currently FLAG_PARTIAL doesn't do anything if the final word in the query has a boolean filter prefix, or if it is in a phrase (either an explicitly quoted one, or one implicitly generated by hyphens or other punctuation). It also doesn't do anything if if the final word is part of a value range. In Xapian 1.2.x, you needed to tell the QueryParser object which database to expand wildcards from by calling set_database(). In Xapian 1.3.3, OP_WILDCARD was added and wildcards are now expanded when Enquire::get_mset() is called, with the expansion using the database being searched.
FLAG_SPELLING_CORRECTION	Enable spelling correction. For each word in the query which doesn't exist as a term in the database, Database::get_spelling_suggestion() will be called and if a suggestion is returned, a corrected version of the query string will be built up which can be read using QueryParser::get_corrected_query_string(). The query returned is based on the uncorrected query string however - if you want a parsed query based on the corrected query string, you must call QueryParser::parse_query() again. NB: You must also call set_database() for this to work.
FLAG_SYNONYM	Enable synonym operator '~'. NB: You must also call set_database() for this to work.
FLAG_AUTO_SYNONYMS	Enable automatic use of synonyms for single terms. NB: You must also call set_database() for this to work.
FLAG_AUTO_MULTIWORD_SYNONYMS	Enable automatic use of synonyms for single terms and groups of terms. NB: You must also call set_database() for this to work.
FLAG_NGRAMS	Generate n-grams for scripts without explicit word breaks. Spans of characters in such scripts are split into unigrams and bigrams, with the unigrams carrying positional information. Text in other scripts is split into words as normal. The TermGenerator::FLAG_NGRAMS flag needs to have been used at index time. This mode can also be enabled in 1.2.8 and later by setting environment variable XAPIAN_CJK_NGRAM to a non-empty value (but doing so was deprecated in 1.4.11). In 1.4.x this feature was specific to CJK (Chinese, Japanese and Korean), but in 1.5.0 it's been extended to other languages. To reflect this change the new and preferred name is FLAG_NGRAMS, which was added as an alias for forward compatibility in Xapian 1.4.23. Use FLAG_CJK_NGRAM instead if you aim to support Xapian < 1.4.23. @since Added in Xapian 1.4.23.
FLAG_CJK_NGRAM	Generate n-grams for scripts without explicit word breaks. Old name - use FLAG_NGRAMS instead unless you aim to support Xapian < 1.4.23. @since Added in Xapian 1.3.4 and 1.2.22.
FLAG_ACCUMULATE	Accumulate unstem and stoplist results. By default, the unstem and stoplist data is reset by a call to parse_query(), which makes sense if you use the same QueryParser object to parse a series of independent queries. If you're using the same QueryParser object to parse several fields on the same query form, you may want to have the unstem and stoplist data combined for all of them, in which case you can use this flag to prevent this data from being reset. @since Added in Xapian 1.4.18.
FLAG_NO_POSITIONS	Produce a query which doesn't use positional information. With this flag enabled, no positional information will be used and any query operations which would use it are replaced by the nearest equivalent which doesn't (so phrase searches, NEAR and ADJ will result in OP_AND). @since Added in Xapian 1.4.19.
FLAG_DEFAULT	The default flags. Used if you don't explicitly pass any to @a parse_query(). The default flags are FLAG_PHRASE\|FLAG_BOOLEAN\|FLAG_LOVEHATE. Added in Xapian 1.0.11.

Member Function Documentation

◆ add_boolean_prefix() [1/3]

void Xapian::QueryParser::add_boolean_prefix	(	const std::string &	field,
		const std::string &	prefix,
		bool	exclusive
	)

inline

Add a boolean term prefix allowing the user to restrict a search with a boolean filter specified in the free text query.

This is an older version of this method - use the version with the grouping parameter in preference to this one.

Parameters

field	The user visible field name, which may not be empty for a boolean filter. Currently this needs to consist of characters for which Xapian::Unicode::is_wordchar() is true (approximately alphanumerics plus connector punctuation such as `_`). Since 1.4.26 it can optionally end in a `:` for consistency with how range prefixes are specified.
prefix	The term prefix to map this to
exclusive	Controls how multiple filters are combined. If true then prefix is used as the `grouping` value, so terms with the same prefix are combined with OP_OR, then the resulting queries are combined with OP_AND. If false, then a unique grouping is created for each filter (this is sometimes useful when each document can have multiple terms with this prefix).

◆ add_boolean_prefix() [2/3]

void Xapian::QueryParser::add_boolean_prefix	(	const std::string &	field,
		const std::string &	prefix,
		const std::string *	grouping = `NULL`
	)

Add a boolean term prefix allowing the user to restrict a search with a boolean filter specified in the free text query.

For example:

qp.add_boolean_prefix("site", "H");

This allows the user to restrict a search with site:xapian.org which will be converted to Hxapian.org combined with any weighted query with Xapian::Query::OP_FILTER.

If multiple boolean filters are specified in a query for the same prefix, they will be combined with the Xapian::Query::OP_OR operator. Then, if there are boolean filters for different prefixes, they will be combined with the Xapian::Query::OP_AND operator.

Multiple fields can be mapped to the same prefix (so for example you can make site: and domain: aliases for each other). Instances of fields with different aliases but the same prefix will still be combined with the OR operator.

For example, if "site" and "domain" map to "H", but author maps to "A", a search for "site:foo domain:bar author:Fred" will map to "(Hfoo OR Hbar) AND Afred".

As of 1.0.4, you can call this method multiple times with the same value of field to allow a single field to be mapped to multiple prefixes. Multiple terms being generated for such a field, and combined with Xapian::Query::OP_OR.

Calling this method with an empty string for field will cause a Xapian::InvalidArgumentError.

If you call add_prefix() and add_boolean_prefix() for the same value of field, a Xapian::InvalidOperationError exception will be thrown.

In 1.0.3 and earlier, subsequent calls to this method with the same value of field had no effect.

Parameters

field	The user visible field name, which may not be empty for a boolean filter. Currently this needs to consist of characters for which Xapian::Unicode::is_wordchar() is true (approximately alphanumerics plus connector punctuation such as `_`). Since 1.4.26 it can optionally end in a `:` for consistency with how range prefixes are specified.
prefix	The term prefix to map this to
grouping	Controls how multiple filters are combined - filters with the same grouping value are combined with OP_OR, then the resulting queries are combined with OP_AND. If NULL, then field is used for grouping. If an empty string, then a unique grouping is created for each filter (this is sometimes useful when each document can have multiple terms with this prefix). [default: NULL]

◆ add_boolean_prefix() [3/3]

void Xapian::QueryParser::add_boolean_prefix	(	const std::string &	field,
		Xapian::FieldProcessor *	proc,
		bool	exclusive
	)

inline

Register a FieldProcessor for a boolean prefix.

This is an older version of this method - use the version with the grouping parameter in preference to this one.

◆ add_prefix()

void Xapian::QueryParser::add_prefix	(	const std::string &	field,
		const std::string &	prefix
	)

Add a free-text field term prefix.

For example:

qp.add_prefix("author", "A");

This allows the user to search for author:Orwell which will be converted to a search for the term "Aorwell".

Multiple fields can be mapped to the same prefix. For example, you can make title: and subject: aliases for each other.

As of 1.0.4, you can call this method multiple times with the same value of field to allow a single field to be mapped to multiple prefixes. Multiple terms being generated for such a field, and combined with Xapian::Query::OP_OR.

If any prefixes are specified for the empty field name (i.e. you call this method with an empty string as the first parameter) these prefixes will be used for terms without a field specifier. If you do this and also specify the default_prefix parameter to parse_query(), then the default_prefix parameter will override.

If the prefix parameter is empty, then "field:word" will produce the term "word" (and this can be one of several prefixes for a particular field, or for terms without a field specifier).

If you call add_prefix() and add_boolean_prefix() for the same value of field, a Xapian::InvalidOperationError exception will be thrown.

In 1.0.3 and earlier, subsequent calls to this method with the same value of field had no effect.

Parameters

field	The user visible field name. Currently this needs to consist of characters for which Xapian::Unicode::is_wordchar() is true (approximately alphanumerics plus connector punctuation such as `_`). Since 1.4.26 it can optionally end in a `:` for consistency with how range prefixes are specified.
prefix	The term prefix to map this to.

◆ add_valuerangeprocessor()

void Xapian::QueryParser::add_valuerangeprocessor ( Xapian::ValueRangeProcessor * vrproc )

inline

Register a ValueRangeProcessor.

This method is provided for API compatibility with Xapian 1.2.x and is deprecated - use add_rangeprocessor() with a RangeProcessor instead.

Compatibility shim.

References Xapian::BAD_VALUENO, and Xapian::Query::OP_INVALID.

◆ get_corrected_query_string()

std::string Xapian::QueryParser::get_corrected_query_string ( ) const

Get the spelling-corrected query string.

This will only be set if FLAG_SPELLING_CORRECTION is specified when QueryParser::parse_query() was last called.

If there were no corrections, an empty string is returned.

◆ parse_query()

Query Xapian::QueryParser::parse_query	(	const std::string &	query_string,
		unsigned	flags = `FLAG_DEFAULT`,
		const std::string &	default_prefix = `std::string()`
	)

Parse a query.

Parameters

query_string	A free-text query as entered by a user
flags	Zero or more QueryParser::feature_flag specifying what features the QueryParser should support. Combine multiple values with bitwise-or (\|) (default FLAG_DEFAULT).
default_prefix	The default term prefix to use (default none). For example, you can pass "A" when parsing an "Author" field.

Exceptions

If	the query string can't be parsed, then Xapian::QueryParserError is thrown. You can get an English error message to report to the user by catching it and calling get_msg() on the caught exception. The current possible values (in case you want to translate them) are:

Unknown range operation
parse error
Syntax: <expression> AND <expression>
Syntax: <expression> AND NOT <expression>
Syntax: <expression> NOT <expression>
Syntax: <expression> OR <expression>
Syntax: <expression> XOR <expression>

◆ set_database()

void Xapian::QueryParser::set_database ( const Database & db )

Specify the database being searched.

Parameters

db	The database to use for spelling correction (FLAG_SPELLING_CORRECTION), and synonyms (FLAG_SYNONYM, FLAG_AUTO_SYNONYMS, and FLAG_AUTO_MULTIWORD_SYNONYMS).

◆ set_default_op()

void Xapian::QueryParser::set_default_op ( Query::op default_op )

Set the default operator.

Parameters

default_op The operator to use to combine non-filter query items when no explicit operator is used.

So for example, 'weather forecast' is parsed as if it were 'weather OR forecast' by default.

The most useful values for this are OP_OR (the default) and OP_AND. OP_NEAR, OP_PHRASE, OP_ELITE_SET, OP_SYNONYM and OP_MAX are also permitted. Passing other values will result in InvalidArgumentError being thrown.

◆ set_max_expansion()

void Xapian::QueryParser::set_max_expansion	(	Xapian::termcount	max_expansion,
		int	max_type = `Xapian::Query::WILDCARD_LIMIT_ERROR`,
		unsigned	flags = `FLAG_WILDCARD\|FLAG_PARTIAL`
	)

Specify the maximum expansion of a wildcard and/or partial term.

Note: you must also set FLAG_WILDCARD and/or FLAG_PARTIAL in the flags parameter to parse_query() for this setting to have anything to affect.

If you don't call this method, the default settings are no limit on wildcard expansion, and partial terms expanding to the most frequent 100 terms - i.e. as if you'd called:

set_max_expansion(0); set_max_expansion(100, Xapian::Query::WILDCARD_LIMIT_MOST_FREQUENT, Xapian::QueryParser::FLAG_PARTIAL);

Parameters

max_expansion	The maximum number of terms each wildcard in the query can expand to, or 0 for no limit (which is the default).
max_type	Xapian::Query::WILDCARD_LIMIT_ERROR, Xapian::Query::WILDCARD_LIMIT_FIRST or Xapian::Query::WILDCARD_LIMIT_MOST_FREQUENT (default: Xapian::Query::WILDCARD_LIMIT_ERROR).
flags	What to set the limit for (default: FLAG_WILDCARD\|FLAG_PARTIAL, setting the limit for both wildcards and partial terms).

Since: 1.3.3

Referenced by set_max_wildcard_expansion().

◆ set_max_wildcard_expansion()

void Xapian::QueryParser::set_max_wildcard_expansion ( Xapian::termcount max_expansion )

inline

Specify the maximum expansion of a wildcard.

If any wildcard expands to more than max_expansion terms, an exception will be thrown.

This method is provided for API compatibility with Xapian 1.2.x and is deprecated - replace it with:

set_max_wildcard_expansion(max_expansion, Xapian::Query::WILDCARD_LIMIT_ERROR, Xapian::QueryParser::FLAG_WILDCARD);

References FLAG_WILDCARD, set_max_expansion(), and Xapian::Query::WILDCARD_LIMIT_ERROR.

◆ set_stemmer()

void Xapian::QueryParser::set_stemmer ( const Xapian::Stem & stemmer )

Set the stemmer.

This sets the stemming algorithm which will be used by the query parser. The stemming algorithm will be used according to the stemming strategy set by set_stemming_strategy(). As of 1.3.1, this defaults to STEM_SOME, but in earlier versions the default was STEM_NONE. If you want to work with older versions, you should explicitly set a stemming strategy as well as setting a stemmer, otherwise your stemmer won't actually be used.

Parameters

stemmer The Xapian::Stem object to set.

◆ set_stemming_strategy()

void Xapian::QueryParser::set_stemming_strategy ( stem_strategy strategy )

Set the stemming strategy.

This controls how the query parser will apply the stemming algorithm. Note that the stemming algorithm is only applied to words in free-text fields - boolean filter terms are never stemmed.

Parameters

strategy

The strategy to use - possible values are:

STEM_NONE: Don't perform any stemming. (default in Xapian <= 1.3.0)
STEM_SOME: Stem all terms except for those which start with a capital letter, or are followed by certain characters (currently: (/@<>=*[{" ), or are used with operators which need positional information. Stemmed terms are prefixed with 'Z'. (default in Xapian >= 1.3.1)
STEM_SOME_FULL_POS: Like STEM_SOME but also stems terms used with operators which need positional information. Added in Xapian 1.4.8.
STEM_ALL: Stem all terms (note: no 'Z' prefix is added).
STEM_ALL_Z: Stem all terms (note: 'Z' prefix is added). (new in Xapian 1.2.11 and 1.3.1)

◆ set_stopper()

void Xapian::QueryParser::set_stopper ( const Stopper * stop = NULL )

Set the stopper.

Parameters

stop	The Stopper object to set (default NULL, which means no stopwords).

The documentation for this class was generated from the following file:

xapian/queryparser.h

Public Types

Public Member Functions

Detailed Description

Member Enumeration Documentation

◆ feature_flag

Member Function Documentation

◆ add_boolean_prefix() [1/3]

◆ add_boolean_prefix() [2/3]

◆ add_boolean_prefix() [3/3]

◆ add_prefix()

◆ add_valuerangeprocessor()

◆ get_corrected_query_string()

◆ parse_query()

◆ set_database()

◆ set_default_op()

◆ set_max_expansion()

◆ set_max_wildcard_expansion()

◆ set_stemmer()

◆ set_stemming_strategy()

◆ set_stopper()