xapian-core  1.4.20
Public Member Functions | Private Member Functions | Private Attributes | List of all members
MaxPostList Class Reference

N-way OR postlist with wt=max(wt_i). More...

#include <maxpostlist.h>

+ Inheritance diagram for MaxPostList:
+ Collaboration diagram for MaxPostList:

Public Member Functions

template<class RandomItor >
 MaxPostList (RandomItor pl_begin, RandomItor pl_end, MultiMatch *matcher_, Xapian::doccount db_size_)
 Construct from 2 random-access iterators to a container of PostList*, a pointer to the matcher, and the document collection size. More...
 
 ~MaxPostList ()
 
Xapian::doccount get_termfreq_min () const
 Get a lower bound on the number of documents indexed by this term. More...
 
Xapian::doccount get_termfreq_max () const
 Get an upper bound on the number of documents indexed by this term. More...
 
Xapian::doccount get_termfreq_est () const
 Get an estimate of the number of documents indexed by this term. More...
 
double get_maxweight () const
 Return an upper bound on what get_weight() can return. More...
 
Xapian::docid get_docid () const
 Return the current docid. More...
 
Xapian::termcount get_doclength () const
 Return the length of current document. More...
 
Xapian::termcount get_unique_terms () const
 Return the number of unique terms in the current document. More...
 
double get_weight () const
 Return the weight contribution for the current position. More...
 
bool at_end () const
 Return true if the current position is past the last entry in this list. More...
 
double recalc_maxweight ()
 Recalculate the upper bound on what get_weight() can return. More...
 
PositionListread_position_list ()
 Read the position list for the term in the current document and return a pointer to it (owned by the PostList). More...
 
PostListnext (double w_min)
 Advance the current position to the next document in the postlist. More...
 
PostListskip_to (Xapian::docid, double w_min)
 Skip forward to the specified docid. More...
 
std::string get_description () const
 Return a string description of this object. More...
 
Xapian::termcount get_wdf () const
 get_wdf() for MaxPostlist returns the sum of the wdfs of the sub postlists which match the current docid. More...
 
Xapian::termcount count_matching_subqs () const
 Count the number of leaf subqueries which match at the current position. More...
 
- Public Member Functions inherited from Xapian::PostingIterator::Internal
virtual ~Internal ()
 We have virtual methods and want to be able to delete derived classes using a pointer to the base class, so we need a virtual destructor. More...
 
virtual TermFreqs get_termfreq_est_using_stats (const Xapian::Weight::Internal &stats) const
 Get an estimate for the termfreq and reltermfreq, given the stats. More...
 
virtual const std::string * get_sort_key () const
 
virtual const std::string * get_collapse_key () const
 If the collapse key is already known, return it. More...
 
virtual PositionListopen_position_list () const
 Read the position list for the term in the current document and return a pointer to it (not owned by the PostList). More...
 
virtual Internalcheck (Xapian::docid did, double w_min, bool &valid)
 Check if the specified docid occurs in this postlist. More...
 
Internalnext ()
 Advance the current position to the next document in the postlist. More...
 
Internalskip_to (Xapian::docid did)
 Skip forward to the specified docid. More...
 
virtual void gather_position_lists (OrPositionList *orposlist)
 Gather PositionList* objects for a subtree. More...
 
- Public Member Functions inherited from Xapian::Internal::intrusive_base
 intrusive_base ()
 Construct with no references. More...
 

Private Member Functions

void operator= (const MaxPostList &)
 Don't allow assignment. More...
 
 MaxPostList (const MaxPostList &)
 Don't allow copying. More...
 
void erase_sublist (size_t i)
 Erase a sub-postlist. More...
 

Private Attributes

Xapian::docid did
 The current docid, or zero if we haven't started or are at_end. More...
 
size_t n_kids
 The number of sub-postlists. More...
 
PostList ** plist
 Array of pointers to sub-postlists. More...
 
double max_cached
 Cached answer to get_maxweight. More...
 
Xapian::doccount db_size
 The number of documents in the database. More...
 
MultiMatchmatcher
 Pointer to the matcher object, so we can report pruning. More...
 

Additional Inherited Members

- Public Attributes inherited from Xapian::Internal::intrusive_base
unsigned _refs
 Reference count. More...
 
- Protected Member Functions inherited from Xapian::PostingIterator::Internal
 Internal ()
 Only constructable as a base class for derived classes. More...
 

Detailed Description

N-way OR postlist with wt=max(wt_i).

Definition at line 32 of file maxpostlist.h.

Constructor & Destructor Documentation

◆ MaxPostList() [1/2]

MaxPostList::MaxPostList ( const MaxPostList )
private

Don't allow copying.

◆ MaxPostList() [2/2]

template<class RandomItor >
MaxPostList::MaxPostList ( RandomItor  pl_begin,
RandomItor  pl_end,
MultiMatch matcher_,
Xapian::doccount  db_size_ 
)
inline

Construct from 2 random-access iterators to a container of PostList*, a pointer to the matcher, and the document collection size.

Definition at line 72 of file maxpostlist.h.

References at_end(), get_docid(), get_doclength(), get_maxweight(), get_termfreq_est(), get_termfreq_max(), get_termfreq_min(), get_unique_terms(), get_weight(), n_kids, recalc_maxweight(), and ~MaxPostList().

◆ ~MaxPostList()

MaxPostList::~MaxPostList ( )

Definition at line 31 of file maxpostlist.cc.

Referenced by MaxPostList().

Member Function Documentation

◆ at_end()

bool MaxPostList::at_end ( ) const
virtual

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

Implements Xapian::PostingIterator::Internal.

Definition at line 147 of file maxpostlist.cc.

Referenced by MaxPostList().

◆ count_matching_subqs()

Xapian::termcount MaxPostList::count_matching_subqs ( ) const
virtual

Count the number of leaf subqueries which match at the current position.

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 272 of file maxpostlist.cc.

Referenced by read_position_list().

◆ erase_sublist()

void MaxPostList::erase_sublist ( size_t  i)
inlineprivate

Erase a sub-postlist.

Definition at line 58 of file maxpostlist.h.

References n_kids, and MultiMatch::recalc_maxweight().

◆ get_description()

string MaxPostList::get_description ( ) const
virtual

Return a string description of this object.

Implements Xapian::PostingIterator::Internal.

Definition at line 248 of file maxpostlist.cc.

Referenced by read_position_list().

◆ get_docid()

Xapian::docid MaxPostList::get_docid ( ) const
virtual

Return the current docid.

Implements Xapian::PostingIterator::Internal.

Definition at line 89 of file maxpostlist.cc.

Referenced by MaxPostList().

◆ get_doclength()

Xapian::termcount MaxPostList::get_doclength ( ) const
virtual

Return the length of current document.

Implements Xapian::PostingIterator::Internal.

Definition at line 95 of file maxpostlist.cc.

References Assert, and AssertEq.

Referenced by MaxPostList().

◆ get_maxweight()

double MaxPostList::get_maxweight ( ) const
virtual

Return an upper bound on what get_weight() can return.

Implements Xapian::PostingIterator::Internal.

Definition at line 83 of file maxpostlist.cc.

Referenced by MaxPostList().

◆ get_termfreq_est()

Xapian::doccount MaxPostList::get_termfreq_est ( ) const
virtual

Get an estimate of the number of documents indexed by this term.

It should always be true that: get_termfreq_min() <= get_termfreq_est() <= get_termfreq_max()

Implements Xapian::PostingIterator::Internal.

Definition at line 65 of file maxpostlist.cc.

References Assert.

Referenced by MaxPostList().

◆ get_termfreq_max()

Xapian::doccount MaxPostList::get_termfreq_max ( ) const
virtual

Get an upper bound on the number of documents indexed by this term.

Implements Xapian::PostingIterator::Internal.

Definition at line 52 of file maxpostlist.cc.

Referenced by MaxPostList().

◆ get_termfreq_min()

Xapian::doccount MaxPostList::get_termfreq_min ( ) const
virtual

Get a lower bound on the number of documents indexed by this term.

Implements Xapian::PostingIterator::Internal.

Definition at line 42 of file maxpostlist.cc.

Referenced by MaxPostList().

◆ get_unique_terms()

Xapian::termcount MaxPostList::get_unique_terms ( ) const
virtual

Return the number of unique terms in the current document.

Implements Xapian::PostingIterator::Internal.

Definition at line 115 of file maxpostlist.cc.

References Assert, and AssertEq.

Referenced by MaxPostList().

◆ get_wdf()

Xapian::termcount MaxPostList::get_wdf ( ) const
virtual

get_wdf() for MaxPostlist returns the sum of the wdfs of the sub postlists which match the current docid.

The wdf isn't really meaningful in many situations, but if the lists are being combined as a synonym we want the sum of the wdfs, so we do that in general.

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 261 of file maxpostlist.cc.

Referenced by read_position_list().

◆ get_weight()

double MaxPostList::get_weight ( ) const
virtual

Return the weight contribution for the current position.

Implements Xapian::PostingIterator::Internal.

Definition at line 135 of file maxpostlist.cc.

References Assert.

Referenced by MaxPostList().

◆ next()

PostList * MaxPostList::next ( double  w_min)
virtual

Advance the current position to the next document in the postlist.

The list 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.

Parameters
w_minThe minimum weight contribution that is needed (this is just a hint which PostList subclasses may ignore).
Returns
If a non-NULL pointer is returned, then the caller should substitute the returned pointer for its pointer to us, and then delete us. This "pruning" can only happen for a non-leaf subclass of this class.

Implements Xapian::PostingIterator::Internal.

Definition at line 163 of file maxpostlist.cc.

References Xapian::PostingIterator::Internal::get_docid(), Xapian::PostingIterator::Internal::next(), and Xapian::PostingIterator::Internal::skip_to().

◆ operator=()

void MaxPostList::operator= ( const MaxPostList )
private

Don't allow assignment.

◆ read_position_list()

PositionList* MaxPostList::read_position_list ( )
inlinevirtual

Read the position list for the term in the current document and return a pointer to it (owned by the PostList).

The default implementation throws Xapian::UnimplementedError.

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 103 of file maxpostlist.h.

References count_matching_subqs(), get_description(), get_wdf(), Xapian::PostingIterator::Internal::next(), and skip_to().

◆ recalc_maxweight()

double MaxPostList::recalc_maxweight ( )
virtual

Recalculate the upper bound on what get_weight() can return.

If the tree has pruned, get_maxweight() may use cached values. Calling this method instead forces a full recalculation.

Note that this method may be called after the postlist has reached the end. In this situation, the method should return 0.

Implements Xapian::PostingIterator::Internal.

Definition at line 153 of file maxpostlist.cc.

Referenced by MaxPostList().

◆ skip_to()

PostList * MaxPostList::skip_to ( Xapian::docid  did,
double  w_min 
)
virtual

Skip forward 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).

Parameters
w_minThe minimum weight contribution that is needed (this is just a hint which PostList subclasses may ignore).
Returns
If a non-NULL pointer is returned, then the caller should substitute the returned pointer for its pointer to us, and then delete us. This "pruning" can only happen for a non-leaf subclass of this class.

Implements Xapian::PostingIterator::Internal.

Definition at line 208 of file maxpostlist.cc.

References Xapian::PostingIterator::Internal::get_docid(), and Xapian::PostingIterator::Internal::skip_to().

Referenced by read_position_list().

Member Data Documentation

◆ db_size

Xapian::doccount MaxPostList::db_size
private

The number of documents in the database.

Definition at line 52 of file maxpostlist.h.

◆ did

Xapian::docid MaxPostList::did
private

The current docid, or zero if we haven't started or are at_end.

Definition at line 40 of file maxpostlist.h.

◆ matcher

MultiMatch* MaxPostList::matcher
private

Pointer to the matcher object, so we can report pruning.

Definition at line 55 of file maxpostlist.h.

◆ max_cached

double MaxPostList::max_cached
private

Cached answer to get_maxweight.

Definition at line 49 of file maxpostlist.h.

◆ n_kids

size_t MaxPostList::n_kids
private

The number of sub-postlists.

Definition at line 43 of file maxpostlist.h.

Referenced by erase_sublist(), and MaxPostList().

◆ plist

PostList** MaxPostList::plist
private

Array of pointers to sub-postlists.

Definition at line 46 of file maxpostlist.h.


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