xapian-core  1.4.19
Public Types | Public Member Functions | Public Attributes | List of all members
ExceptionalPostingSource Class Reference
+ Inheritance diagram for ExceptionalPostingSource:
+ Collaboration diagram for ExceptionalPostingSource:

Public Types

enum  failmode { NONE, CLONE }
 

Public Member Functions

 ExceptionalPostingSource (failmode fail_)
 
string name () const
 Name of the posting source class. More...
 
PostingSourceclone () const
 Clone the posting source. More...
 
void init (const Xapian::Database &)
 Set this PostingSource to the start of the list of postings. More...
 
Xapian::doccount get_termfreq_min () const
 A lower bound on the number of documents this object can return. More...
 
Xapian::doccount get_termfreq_est () const
 An estimate of the number of documents this object can return. More...
 
Xapian::doccount get_termfreq_max () const
 An upper bound on the number of documents this object can return. More...
 
void next (double)
 Advance the current position to the next matching document. More...
 
void skip_to (Xapian::docid, double)
 Advance to the specified docid. More...
 
bool at_end () const
 Return true if the current position is past the last entry in this list. More...
 
Xapian::docid get_docid () const
 Return the current docid. 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 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...
 
virtual std::string get_description () const
 Return a string describing this object. 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
 

Public Attributes

failmode fail
 
- Public Attributes inherited from Xapian::Internal::opt_intrusive_base
unsigned _refs
 Reference count. More...
 

Additional Inherited Members

- Protected Member Functions inherited from Xapian::Internal::opt_intrusive_base
void release () const
 Start reference counting. More...
 

Detailed Description

Definition at line 322 of file api_serialise.cc.

Member Enumeration Documentation

◆ failmode

Enumerator
NONE 
CLONE 

Definition at line 324 of file api_serialise.cc.

Constructor & Destructor Documentation

◆ ExceptionalPostingSource()

ExceptionalPostingSource::ExceptionalPostingSource ( failmode  fail_)
inline

Definition at line 328 of file api_serialise.cc.

Member Function Documentation

◆ at_end()

bool ExceptionalPostingSource::at_end ( ) const
inlinevirtual

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 350 of file api_serialise.cc.

◆ clone()

PostingSource* ExceptionalPostingSource::clone ( ) const
inlinevirtual

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 334 of file api_serialise.cc.

◆ get_docid()

Xapian::docid ExceptionalPostingSource::get_docid ( ) const
inlinevirtual

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 351 of file api_serialise.cc.

◆ get_termfreq_est()

Xapian::doccount ExceptionalPostingSource::get_termfreq_est ( ) const
inlinevirtual

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 343 of file api_serialise.cc.

◆ get_termfreq_max()

Xapian::doccount ExceptionalPostingSource::get_termfreq_max ( ) const
inlinevirtual

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 344 of file api_serialise.cc.

◆ get_termfreq_min()

Xapian::doccount ExceptionalPostingSource::get_termfreq_min ( ) const
inlinevirtual

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 342 of file api_serialise.cc.

◆ init()

void ExceptionalPostingSource::init ( const Xapian::Database db)
inlinevirtual

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 340 of file api_serialise.cc.

◆ name()

string ExceptionalPostingSource::name ( ) const
inlinevirtual

Name of the posting source class.

This is used when serialising and unserialising posting sources; for example, for performing remote searches.

If the subclass is in a C++ namespace, the namespace should be included in the name, using "::" as a separator. For example, for a PostingSource subclass called "FooPostingSource" in the "Xapian" namespace the result of this call should be "Xapian::FooPostingSource".

This should only be implemented if serialise() and unserialise() are also implemented. The default implementation returns an empty string.

If this returns an empty string, Xapian will assume that serialise() and unserialise() are not implemented.

Reimplemented from Xapian::PostingSource.

Definition at line 330 of file api_serialise.cc.

◆ next()

void ExceptionalPostingSource::next ( double  min_wt)
inlinevirtual

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 346 of file api_serialise.cc.

◆ skip_to()

void ExceptionalPostingSource::skip_to ( Xapian::docid  did,
double  min_wt 
)
inlinevirtual

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 348 of file api_serialise.cc.

Member Data Documentation

◆ fail

failmode ExceptionalPostingSource::fail

Definition at line 326 of file api_serialise.cc.


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