ScaleWeight Class Reference

Xapian::Weight subclass for implementing OP_SCALE_WEIGHT. More...

#include <scaleweight.h>

Inheritance diagram for ScaleWeight:

[legend]Collaboration diagram for ScaleWeight:

[legend]List of all members.

Public Member Functions
ScaleWeight *	clone () const
	Return a new weight object of this type.
	ScaleWeight (Xapian::Weight *real_wt_, double factor_)
	~ScaleWeight ()
std::string	name () const
	Name of the weighting scheme.
std::string	serialise () const
	Serialise object parameters into a string.
ScaleWeight *	unserialise (const std::string &s) const
	Create object given string serialisation returned by serialise().
Xapian::weight	get_sumpart (Xapian::termcount wdf, Xapian::doclength len) const
	Get a weight which is part of the sum over terms being performed.
Xapian::weight	get_maxpart () const
	Gets the maximum value that get_sumpart() may return.
Xapian::weight	get_sumextra (Xapian::doclength len) const
	Get an extra weight for a document to add to the sum calculated over the query terms.
Xapian::weight	get_maxextra () const
	Gets the maximum value that get_sumextra() may return.
bool	get_sumpart_needs_doclength () const
	return false if the weight object doesn't need doclength
Private Attributes
Xapian::Weight *	real_wt
double	factor

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Detailed Description

Xapian::Weight subclass for implementing OP_SCALE_WEIGHT.

Definition at line 27 of file scaleweight.h.

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Constructor & Destructor Documentation

ScaleWeight::ScaleWeight	(	Xapian::Weight *	real_wt_,
		double	factor_
	)			[inline]

Definition at line 34 of file scaleweight.h.

Referenced by clone(), and unserialise().

ScaleWeight::~ScaleWeight

(

)

Definition at line 32 of file scaleweight.cc.

References real_wt.

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Member Function Documentation

ScaleWeight * ScaleWeight::clone

(

)

const [virtual]

Return a new weight object of this type.

A subclass called FooWeight taking parameters param1 and param2 should implement this as:

virtual FooWeight * clone() const { return new FooWeight(param1, param2); }

Implements Xapian::Weight.

Definition at line 28 of file scaleweight.cc.

References Xapian::Weight::clone(), factor, real_wt, and ScaleWeight().

std::string ScaleWeight::name

(

)

const [virtual]

Name of the weighting scheme.

If the subclass is called FooWeight, this should return "Foo".

Implements Xapian::Weight.

Definition at line 35 of file scaleweight.cc.

std::string ScaleWeight::serialise

(

)

const [virtual]

Serialise object parameters into a string.

Implements Xapian::Weight.

Definition at line 40 of file scaleweight.cc.

References factor, real_wt, Xapian::Weight::serialise(), and serialise_double().

ScaleWeight * ScaleWeight::unserialise

(

const std::string &

s

)

const [virtual]

Create object given string serialisation returned by serialise().

Implements Xapian::Weight.

Definition at line 45 of file scaleweight.cc.

References real_wt, ScaleWeight(), Xapian::Weight::unserialise(), and unserialise_double().

Xapian::weight ScaleWeight::get_sumpart	(	Xapian::termcount	wdf,
		Xapian::doclength	len
	)			const [virtual]

Get a weight which is part of the sum over terms being performed.

This returns a weight for a given term and document. These weights are summed to give a total weight for the document.

Parameters:

	wdf	the within document frequency of the term.
	len	the (unnormalised) document length.

Implements Xapian::Weight.

Definition at line 55 of file scaleweight.cc.

References factor, Xapian::Weight::get_sumpart(), and real_wt.

Xapian::weight ScaleWeight::get_maxpart

(

)

const [virtual]

Gets the maximum value that get_sumpart() may return.

This is used in optimising searches, by having the postlist tree decay appropriately when parts of it can have limited, or no, further effect.

Implements Xapian::Weight.

Definition at line 61 of file scaleweight.cc.

References factor, Xapian::Weight::get_maxpart(), and real_wt.

Xapian::weight ScaleWeight::get_sumextra

(

Xapian::doclength

len

)

const [virtual]

Get an extra weight for a document to add to the sum calculated over the query terms.

This returns a weight for a given document, and is used by some weighting schemes to account for influence such as document length.

Parameters:

len

the (unnormalised) document length.

Implements Xapian::Weight.

Definition at line 65 of file scaleweight.cc.

References factor, Xapian::Weight::get_sumextra(), and real_wt.

Xapian::weight ScaleWeight::get_maxextra

(

)

const [virtual]

Gets the maximum value that get_sumextra() may return.

This is used in optimising searches.

Implements Xapian::Weight.

Definition at line 69 of file scaleweight.cc.

References factor, Xapian::Weight::get_maxextra(), and real_wt.

bool ScaleWeight::get_sumpart_needs_doclength

(

)

const [virtual]

return false if the weight object doesn't need doclength

Reimplemented from Xapian::Weight.

Definition at line 73 of file scaleweight.cc.

References Xapian::Weight::get_sumpart_needs_doclength(), and real_wt.

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Member Data Documentation

Xapian::Weight* ScaleWeight::real_wt [private]

Definition at line 28 of file scaleweight.h.

Referenced by clone(), get_maxextra(), get_maxpart(), get_sumextra(), get_sumpart(), get_sumpart_needs_doclength(), serialise(), unserialise(), and ~ScaleWeight().

double ScaleWeight::factor [private]

Definition at line 30 of file scaleweight.h.

Referenced by clone(), get_maxextra(), get_maxpart(), get_sumextra(), get_sumpart(), and serialise().

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

• matcher/scaleweight.h
• matcher/scaleweight.cc

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