xapian-core  1.4.26
Public Member Functions | Private Attributes | List of all members
EstimatePS Class Reference

PostingSource subclass for injecting tf bounds and estimate. More...

+ Inheritance diagram for EstimatePS:
+ Collaboration diagram for EstimatePS:

Public Member Functions

 EstimatePS (Xapian::doccount lb_, Xapian::doccount est_, Xapian::doccount ub_)
 
PostingSourceclone () const override
 Clone the posting source. More...
 
void init (const Xapian::Database &) override
 Set this PostingSource to the start of the list of postings. More...
 
Xapian::doccount get_termfreq_min () const override
 A lower bound on the number of documents this object can return. More...
 
Xapian::doccount get_termfreq_est () const override
 An estimate of the number of documents this object can return. More...
 
Xapian::doccount get_termfreq_max () const override
 An upper bound on the number of documents this object can return. More...
 
void next (double) override
 Advance the current position to the next matching document. More...
 
void skip_to (Xapian::docid, double) override
 Advance to the specified docid. More...
 
bool at_end () const override
 Return true if the current position is past the last entry in this list. More...
 
Xapian::docid get_docid () const override
 Return the current docid. More...
 
string get_description () const override
 Return a string describing this object. More...
 
- Public Member Functions inherited from Xapian::PostingSource
 PostingSource ()
 Allow subclasses to be instantiated. More...
 
virtual ~PostingSource ()
 
void set_maxweight (double max_weight)
 Specify an upper bound on what get_weight() will return from now on. More...
 
double get_maxweight () const
 Return the currently set upper bound on what get_weight() can return. More...
 
virtual double get_weight () const
 Return the weight contribution for the current document. More...
 
virtual bool check (Xapian::docid did, double min_wt)
 Check if the specified docid occurs. More...
 
virtual std::string name () const
 Name of the posting source class. More...
 
virtual std::string serialise () const
 Serialise object parameters into a string. More...
 
virtual PostingSourceunserialise (const std::string &serialised) const
 Create object given string serialisation returned by serialise(). More...
 
virtual PostingSourceunserialise_with_registry (const std::string &serialised, const Registry &registry) const
 Create object given string serialisation returned by serialise(). More...
 
PostingSourcerelease ()
 Start reference counting this object. More...
 
const PostingSourcerelease () const
 Start reference counting this object. More...
 
- Public Member Functions inherited from Xapian::Internal::opt_intrusive_base
 opt_intrusive_base (const opt_intrusive_base &)
 
opt_intrusive_baseoperator= (const opt_intrusive_base &)
 
 opt_intrusive_base ()
 Construct object which is initially not reference counted. More...
 
virtual ~opt_intrusive_base ()
 
void ref () const
 
void unref () const
 

Private Attributes

Xapian::doccount lb
 
Xapian::doccount est
 
Xapian::doccount ub
 

Additional Inherited Members

- Public Attributes inherited from Xapian::Internal::opt_intrusive_base
unsigned _refs
 Reference count. More...
 
- Protected Member Functions inherited from Xapian::Internal::opt_intrusive_base
void release () const
 Start reference counting. More...
 

Detailed Description

PostingSource subclass for injecting tf bounds and estimate.

Definition at line 835 of file api_postingsource.cc.

Constructor & Destructor Documentation

◆ EstimatePS()

EstimatePS::EstimatePS ( Xapian::doccount  lb_,
Xapian::doccount  est_,
Xapian::doccount  ub_ 
)
inline

Definition at line 839 of file api_postingsource.cc.

Member Function Documentation

◆ at_end()

bool EstimatePS::at_end ( ) const
inlineoverridevirtual

Return true if the current position is past the last entry in this list.

At least one of next(), skip_to() or check() will be called before this method is first called.

Implements Xapian::PostingSource.

Definition at line 865 of file api_postingsource.cc.

◆ clone()

PostingSource* EstimatePS::clone ( ) const
inlineoverridevirtual

Clone the posting source.

The clone should inherit the configuration of the parent, but need not inherit the state. ie, the clone does not need to be in the same iteration position as the original: the matcher will always call init() on the clone before attempting to move the iterator, or read the information about the current position of the iterator.

This may return NULL to indicate that cloning is not supported. In this case, the PostingSource may only be used with a single-database search.

The default implementation returns NULL.

Note that the returned object will be deallocated by Xapian after use with "delete". If you want to handle the deletion in a special way (for example when wrapping the Xapian API for use from another language) then you can define a static operator delete method in your subclass as shown here: https://trac.xapian.org/ticket/554#comment:1

Reimplemented from Xapian::PostingSource.

Definition at line 845 of file api_postingsource.cc.

◆ get_description()

string EstimatePS::get_description ( ) const
inlineoverridevirtual

Return a string describing this object.

This default implementation returns a generic answer. This default it provided to avoid forcing those deriving their own PostingSource subclass from having to implement this (they may not care what get_description() gives for their subclass).

Reimplemented from Xapian::PostingSource.

Definition at line 873 of file api_postingsource.cc.

◆ get_docid()

Xapian::docid EstimatePS::get_docid ( ) const
inlineoverridevirtual

Return the current docid.

This method may assume that it will only be called when there is a "current document". See get_weight() for details.

Note: in the case of a multi-database search, the returned docid should be in the single subdatabase relevant to this posting source. See the init() method for details.

Implements Xapian::PostingSource.

Definition at line 869 of file api_postingsource.cc.

References FAIL_TEST.

◆ get_termfreq_est()

Xapian::doccount EstimatePS::get_termfreq_est ( ) const
inlineoverridevirtual

An estimate of the number of documents this object can return.

It must always be true that:

get_termfreq_min() <= get_termfreq_est() <= get_termfreq_max()

Xapian will always call init() on a PostingSource before calling this for the first time.

Implements Xapian::PostingSource.

Definition at line 853 of file api_postingsource.cc.

References est().

◆ get_termfreq_max()

Xapian::doccount EstimatePS::get_termfreq_max ( ) const
inlineoverridevirtual

An upper bound on the number of documents this object can return.

Xapian will always call init() on a PostingSource before calling this for the first time.

Implements Xapian::PostingSource.

Definition at line 855 of file api_postingsource.cc.

◆ get_termfreq_min()

Xapian::doccount EstimatePS::get_termfreq_min ( ) const
inlineoverridevirtual

A lower bound on the number of documents this object can return.

Xapian will always call init() on a PostingSource before calling this for the first time.

Implements Xapian::PostingSource.

Definition at line 851 of file api_postingsource.cc.

◆ init()

void EstimatePS::init ( const Xapian::Database db)
inlineoverridevirtual

Set this PostingSource to the start of the list of postings.

This is called automatically by the matcher prior to each query being processed.

If a PostingSource is used for multiple searches, init() will therefore be called multiple times, and must handle this by using the database passed in the most recent call.

Parameters
dbThe database which the PostingSource should iterate through.

Note: in the case of a multi-database search, a separate PostingSource will be used for each database (the separate PostingSources will be obtained using clone()), and each PostingSource will be passed one of the sub-databases as the db parameter here. The db parameter will therefore always refer to a single database. All docids passed to, or returned from, the PostingSource refer to docids in that single database, rather than in the multi-database.

Implements Xapian::PostingSource.

Definition at line 849 of file api_postingsource.cc.

◆ next()

void EstimatePS::next ( double  min_wt)
inlineoverridevirtual

Advance the current position to the next matching document.

The PostingSource starts before the first entry in the list, so next(), skip_to() or check() must be called before any methods which need the context of the current position.

Xapian will always call init() on a PostingSource before calling this for the first time.

Parameters
min_wtThe minimum weight contribution that is needed (this is just a hint which subclasses may ignore).

Implements Xapian::PostingSource.

Definition at line 857 of file api_postingsource.cc.

References FAIL_TEST.

◆ skip_to()

void EstimatePS::skip_to ( Xapian::docid  did,
double  min_wt 
)
inlineoverridevirtual

Advance to the specified docid.

If the specified docid isn't in the list, position ourselves on the first document after it (or at_end() if no greater docids are present).

If the current position is already the specified docid, this method will leave the position unmodified.

If the specified docid is earlier than the current position, the behaviour is unspecified. A sensible behaviour would be to leave the current position unmodified, but it is also reasonable to move to the specified docid.

The default implementation calls next() repeatedly, which works but skip_to() can often be implemented much more efficiently.

Xapian will always call init() on a PostingSource before calling this for the first time.

Note: in the case of a multi-database search, the docid specified is the docid in the single subdatabase relevant to this posting source. See the init() method for details.

Parameters
didThe document id to advance to.
min_wtThe minimum weight contribution that is needed (this is just a hint which subclasses may ignore).

Reimplemented from Xapian::PostingSource.

Definition at line 861 of file api_postingsource.cc.

References FAIL_TEST.

Member Data Documentation

◆ est

Xapian::doccount EstimatePS::est
private

Definition at line 836 of file api_postingsource.cc.

◆ lb

Xapian::doccount EstimatePS::lb
private

Definition at line 836 of file api_postingsource.cc.

◆ ub

Xapian::doccount EstimatePS::ub
private

Definition at line 836 of file api_postingsource.cc.


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