Xapian::Query Class Reference

Class representing a query. More...

#include <query.h>

Collaboration diagram for Xapian::Query:

[legend]List of all members.

Public Types
enum	op {   OP_AND, OP_OR, OP_AND_NOT, OP_XOR,   OP_AND_MAYBE, OP_FILTER, OP_NEAR, OP_PHRASE,   OP_VALUE_RANGE, OP_SCALE_WEIGHT, OP_ELITE_SET, OP_VALUE_GE,   OP_VALUE_LE }
	Enum of possible query operations. More...
typedef std::vector< Internal * >	subquery_list
	The container type for storing pointers to subqueries.
typedef int	op_t
	Type storing the operation.
Public Member Functions
	Query (const Query &copyme)
	Copy constructor.
Query &	operator= (const Query &copyme)
	Assignment.
	Query ()
	Default constructor: makes an empty query which matches no documents.
	~Query ()
	Destructor.
	Query (const std::string &tname_, Xapian::termcount wqf_=1, Xapian::termpos pos_=0)
	A query consisting of a single term.
	Query (Query::op op_, const Query &left, const Query &right)
	A query consisting of two subqueries, opp-ed together.
	Query (Query::op op_, const std::string &left, const std::string &right)
	A query consisting of two termnames opp-ed together.
template<class Iterator>
	Query (Query::op op_, Iterator qbegin, Iterator qend, Xapian::termcount parameter=0)
	Combine a number of Xapian::Query-s with the specified operator.
	XAPIAN_DEPRECATED (Query(Query::op op_, Xapian::Query q))
	Apply the specified operator to a single Xapian::Query object.
	Query (Query::op op_, Xapian::Query q, double parameter)
	Apply the specified operator to a single Xapian::Query object, with a double parameter.
	Query (Query::op op_, Xapian::valueno valno, const std::string &begin, const std::string &end)
	Construct a value range query on a document value.
	Query (Query::op op_, Xapian::valueno valno, const std::string &value)
	Construct a value comparison query on a document value.
Xapian::termcount	get_length () const
	Get the length of the query, used by some ranking formulae.
TermIterator	get_terms_begin () const
	Return a Xapian::TermIterator returning all the terms in the query, in order of termpos.
TermIterator	get_terms_end () const
	Return a Xapian::TermIterator to the end of the list of terms in the query.
bool	empty () const
	Test if the query is empty (i.e.
std::string	get_description () const
	Return a string describing this object.
	Internal (const Query::Internal &copyme)
	Copy constructor.
void	operator= (const Query::Internal &copyme)
	Assignment.
	Internal (const std::string &tname_, Xapian::termcount wqf_=1, Xapian::termpos term_pos_=0)
	A query consisting of a single term.
	Internal (op_t op_, Xapian::termcount parameter)
	Create internals given only the operator and a parameter.
	Internal (op_t op_, Xapian::valueno valno, const std::string &begin, const std::string &end)
	Construct a range query on a document value.
	Internal (op_t op_, Xapian::valueno valno, const std::string &value)
	Construct a value greater-than-or-equal query on a document value.
	~Internal ()
	Destructor.
void	add_subquery (const Query::Internal *subq)
	Add a subquery.
void	set_dbl_parameter (double dbl_parameter_)
double	get_dbl_parameter () const
Query::Internal *	end_construction ()
	Finish off the construction.
std::string	serialise () const
	Return a string in an easily parsed form which contains all the information in a query.
std::string	get_description () const
	Return a string describing this object.
Xapian::termcount	get_parameter () const
	Get the numeric parameter used in this query.
Xapian::termcount	get_length () const
	Get the length of the query, used by some ranking formulae.
TermIterator	get_terms () const
	Return an iterator over all the terms in the query, in order of termpos.
Static Public Member Functions
static Xapian::Query::Internal *	unserialise (const std::string &s)
Static Public Attributes
static Xapian::Query	MatchAll
	A query which matches all documents in the database.
static Xapian::Query	MatchNothing
	A query which matches no documents.
static const int	OP_LEAF = -1
Friends
class	::LocalSubMatch
class	::MultiMatch
class	::QueryOptimiser
struct	::SortPosName
class	Query

---

Detailed Description

Class representing a query.

Queries are represented as a tree of objects.

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Member Typedef Documentation

typedef std::vector<Internal *> Xapian::Query::subquery_list

The container type for storing pointers to subqueries.

typedef int Xapian::Query::op_t

Type storing the operation.

---

Member Enumeration Documentation

enum Xapian::Query::op

Enum of possible query operations.

Enumerator:

OP_AND	Return iff both subqueries are satisfied.
OP_OR	Return if either subquery is satisfied.
OP_AND_NOT	Return if left but not right satisfied.
OP_XOR	Return if one query satisfied, but not both.
OP_AND_MAYBE	Return iff left satisfied, but use weights from both.
OP_FILTER	As AND, but use only weights from left subquery.
OP_NEAR	Find occurrences of a list of terms with all the terms occurring within a specified window of positions. Each occurrence of a term must be at a different position, but the order they appear in is irrelevant. The window parameter should be specified for this operation, but will default to the number of terms in the list.
OP_PHRASE	Find occurrences of a list of terms with all the terms occurring within a specified window of positions, and all the terms appearing in the order specified. Each occurrence of a term must be at a different position. The window parameter should be specified for this operation, but will default to the number of terms in the list.
OP_VALUE_RANGE	Filter by a range test on a document value.
OP_SCALE_WEIGHT	Scale the weight of a subquery by the specified factor. A factor of 0 means this subquery will contribute no weight to the query - it will act as a purely boolean subquery. If the factor is negative, Xapian::InvalidArgumentError will be thrown.
OP_ELITE_SET	Select an elite set from the subqueries, and perform a query with these combined as an OR query.
OP_VALUE_GE	Filter by a greater-than-or-equal test on a document value.
OP_VALUE_LE	Filter by a less-than-or-equal test on a document value.

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Constructor & Destructor Documentation

Xapian::Query::Query

(

const Query &

copyme

)

Copy constructor.

Xapian::Query::Query

(

)

Default constructor: makes an empty query which matches no documents.

Also useful for defining a Query object to be assigned to later.

An exception will be thrown if an attempt is made to use an undefined query when building up a composite query.

Xapian::Query::~Query

(

)

Destructor.

Xapian::Query::Query	(	const std::string &	tname_,
		Xapian::termcount	wqf_ = 1,
		Xapian::termpos	pos_ = 0
	)

A query consisting of a single term.

Xapian::Query::Query	(	Query::op	op_,
		const Query &	left,
		const Query &	right
	)

A query consisting of two subqueries, opp-ed together.

Xapian::Query::Query	(	Query::op	op_,
		const std::string &	left,
		const std::string &	right
	)

A query consisting of two termnames opp-ed together.

template<class Iterator>

Xapian::Query::Query	(	Query::op	op_,
		Iterator	qbegin,
		Iterator	qend,
		Xapian::termcount	parameter = 0
	)			[inline]

Combine a number of Xapian::Query-s with the specified operator.

The Xapian::Query objects are specified with begin and end iterators.

AND, OR, NEAR and PHRASE can take any number of subqueries. Other operators take exactly two subqueries.

The iterators may be to Xapian::Query objects, pointers to Xapian::Query objects, or termnames (std::string-s).

For NEAR and PHRASE, a window size can be specified in parameter.

For ELITE_SET, the elite set size can be specified in parameter.

Xapian::Query::Query	(	Query::op	op_,
		Xapian::Query	q,
		double	parameter
	)

Apply the specified operator to a single Xapian::Query object, with a double parameter.

Xapian::Query::Query	(	Query::op	op_,
		Xapian::valueno	valno,
		const std::string &	begin,
		const std::string &	end
	)

Construct a value range query on a document value.

A value range query matches those documents which have a value stored in the slot given by valno which is in the range specified by begin and end (in lexicographical order), including the endpoints.

Parameters:

	op_	The operator to use for the query. Currently, must be OP_VALUE_RANGE.
	valno	The slot number to get the value from.
	begin	The start of the range.
	end	The end of the range.

Xapian::Query::Query	(	Query::op	op_,
		Xapian::valueno	valno,
		const std::string &	value
	)

Construct a value comparison query on a document value.

This query matches those documents which have a value stored in the slot given by valno which compares, as specified by the operator, to value.

Parameters:

	op_	The operator to use for the query. Currently, must be OP_VALUE_GE or OP_VALUE_LE.
	valno	The slot number to get the value from.
	value	The value to compare.

Xapian::Query::~Internal

(

)

Destructor.

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Member Function Documentation

Query& Xapian::Query::operator=

(

const Query &

copyme

)

Assignment.

Xapian::Query::XAPIAN_DEPRECATED

(

Query(Query::op op_, Xapian::Query q)

)

Apply the specified operator to a single Xapian::Query object.

Deprecated:

This method is deprecated because it isn't useful, since none of the current query operators can be usefully applied to a single subquery with a parameter value.

Xapian::termcount Xapian::Query::get_length

(

)

const

Get the length of the query, used by some ranking formulae.

This value is calculated automatically - if you want to override it you can pass a different value to Enquire::set_query().

TermIterator Xapian::Query::get_terms_begin

(

)

const

Return a Xapian::TermIterator returning all the terms in the query, in order of termpos.

If multiple terms have the same term position, their order is unspecified. Duplicates (same term and termpos) will be removed.

TermIterator Xapian::Query::get_terms_end

(

)

const [inline]

Return a Xapian::TermIterator to the end of the list of terms in the query.

bool Xapian::Query::empty

(

)

const

Test if the query is empty (i.e.

was constructed using the default ctor or with an empty iterator ctor).

std::string Xapian::Query::get_description

(

)

const

Return a string describing this object.

Xapian::Query::Internal

(

const Query::Internal &

copyme

)

Copy constructor.

void Xapian::Query::operator=

(

const Query::Internal &

copyme

)

Assignment.

Xapian::Query::Internal	(	const std::string &	tname_,
		Xapian::termcount	wqf_ = 1,
		Xapian::termpos	term_pos_ = 0
	)			[explicit]

A query consisting of a single term.

Xapian::Query::Internal	(	op_t	op_,
		Xapian::termcount	parameter
	)

Create internals given only the operator and a parameter.

Xapian::Query::Internal	(	op_t	op_,
		Xapian::valueno	valno,
		const std::string &	begin,
		const std::string &	end
	)

Construct a range query on a document value.

Xapian::Query::Internal	(	op_t	op_,
		Xapian::valueno	valno,
		const std::string &	value
	)

Construct a value greater-than-or-equal query on a document value.

void Xapian::Query::add_subquery

(

const Query::Internal *

subq

)

Add a subquery.

Query::Internal* Xapian::Query::end_construction

(

)

Finish off the construction.

std::string Xapian::Query::serialise

(

)

const [inline]

Return a string in an easily parsed form which contains all the information in a query.

std::string Xapian::Query::get_description

(

)

const

Return a string describing this object.

Xapian::termcount Xapian::Query::get_parameter

(

)

const [inline]

Get the numeric parameter used in this query.

This is used by the QueryParser to get the value number for VALUE_RANGE queries. It should be replaced by a public method on the Query class at some point, but the API which should be used for that is unclear, so this is a temporary workaround.

Xapian::termcount Xapian::Query::get_length

(

)

const

Get the length of the query, used by some ranking formulae.

This value is calculated automatically - if you want to override it you can pass a different value to Enquire::set_query().

TermIterator Xapian::Query::get_terms

(

)

const

Return an iterator over all the terms in the query, in order of termpos.

If multiple terms have the same term position, their order is unspecified. Duplicates (same term and termpos) will be removed.

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Member Data Documentation

Xapian::Query Xapian::Query::MatchAll [static]

A query which matches all documents in the database.

Xapian::Query Xapian::Query::MatchNothing [static]

A query which matches no documents.

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

• include/xapian/query.h

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