xapian-core  1.4.21
Public Member Functions | Private Member Functions | Private Attributes | List of all members
MergePostList Class Reference

A postlist comprising postlists from different databases merged together. More...

#include <mergepostlist.h>

+ Inheritance diagram for MergePostList:
+ Collaboration diagram for MergePostList:

Public Member Functions

Xapian::termcount get_wdf () const
 Return the wdf for the document at the current position. 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_min () const
 Get a lower 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...
 
Xapian::docid get_docid () const
 Return the current docid. More...
 
double get_weight () const
 Return the weight contribution for the current position. More...
 
const string * get_sort_key () const
 
const string * get_collapse_key () const
 If the collapse key is already known, return it. More...
 
double get_maxweight () const
 Return an upper bound on what get_weight() can return. More...
 
double recalc_maxweight ()
 Recalculate the upper bound on what get_weight() can return. More...
 
PostListnext (double w_min)
 Advance the current position to the next document in the postlist. More...
 
PostListskip_to (Xapian::docid did, double w_min)
 Skip forward to the specified docid. More...
 
bool at_end () const
 Return true if the current position is past the last entry in this list. More...
 
string get_description () const
 Return a string description of this object. More...
 
virtual Xapian::termcount get_doclength () const
 Return the document length of the document the current term comes from. More...
 
virtual Xapian::termcount get_unique_terms () const
 Return the number of unique terms in the document. More...
 
Xapian::termcount count_matching_subqs () const
 Count the number of leaf subqueries which match at the current position. More...
 
 MergePostList (const std::vector< PostList *> &plists_, MultiMatch *matcher_, ValueStreamDocument &vsdoc_)
 
 ~MergePostList ()
 
- 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 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...
 
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

 MergePostList (const MergePostList &)
 
MergePostListoperator= (const MergePostList &)
 

Private Attributes

double w_max
 
vector< PostList * > plists
 
int current
 
MultiMatchmatcher
 The object which is using this postlist to perform a match. More...
 
ValueStreamDocumentvsdoc
 Document proxy used for valuestream caching. 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

A postlist comprising postlists from different databases merged together.

Definition at line 35 of file mergepostlist.h.

Constructor & Destructor Documentation

◆ MergePostList() [1/2]

MergePostList::MergePostList ( const MergePostList )
private

◆ MergePostList() [2/2]

MergePostList::MergePostList ( const std::vector< PostList *> &  plists_,
MultiMatch matcher_,
ValueStreamDocument vsdoc_ 
)
inline

Definition at line 93 of file mergepostlist.h.

References ~MergePostList().

◆ ~MergePostList()

MergePostList::~MergePostList ( )

Definition at line 38 of file mergepostlist.cc.

References LOGCALL_DTOR, and plists.

Referenced by MergePostList().

Member Function Documentation

◆ at_end()

bool MergePostList::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 179 of file mergepostlist.cc.

References Assert, current, LOGCALL, plists, and RETURN.

Referenced by next().

◆ count_matching_subqs()

Xapian::termcount MergePostList::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 214 of file mergepostlist.cc.

References current, LOGCALL, plists, and RETURN.

◆ get_collapse_key()

const string * MergePostList::get_collapse_key ( ) const
virtual

If the collapse key is already known, return it.

This is implemented by MSetPostList (and MergePostList). Other subclasses rely on the default implementation which just returns NULL.

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 151 of file mergepostlist.cc.

References Assert, current, LOGCALL, plists, and RETURN.

◆ get_description()

string MergePostList::get_description ( ) const
virtual

Return a string description of this object.

Implements Xapian::PostingIterator::Internal.

Definition at line 187 of file mergepostlist.cc.

References plists.

◆ get_docid()

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

Return the current docid.

Implements Xapian::PostingIterator::Internal.

Definition at line 125 of file mergepostlist.cc.

References Assert, current, LOGCALL, plists, and RETURN.

◆ get_doclength()

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

Return the document length of the document the current term comes from.

Implements Xapian::PostingIterator::Internal.

Definition at line 198 of file mergepostlist.cc.

References Assert, current, LOGCALL, plists, and RETURN.

◆ get_maxweight()

double MergePostList::get_maxweight ( ) const
virtual

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

Implements Xapian::PostingIterator::Internal.

Definition at line 159 of file mergepostlist.cc.

References LOGCALL, RETURN, and w_max.

◆ get_sort_key()

const string * MergePostList::get_sort_key ( ) const
virtual

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 143 of file mergepostlist.cc.

References Assert, current, LOGCALL, plists, and RETURN.

◆ get_termfreq_est()

Xapian::doccount MergePostList::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 112 of file mergepostlist.cc.

References LOGCALL, plists, and RETURN.

◆ get_termfreq_max()

Xapian::doccount MergePostList::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 86 of file mergepostlist.cc.

References LOGCALL, plists, and RETURN.

◆ get_termfreq_min()

Xapian::doccount MergePostList::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 99 of file mergepostlist.cc.

References LOGCALL, plists, and RETURN.

◆ get_unique_terms()

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

Return the number of unique terms in the document.

Implements Xapian::PostingIterator::Internal.

Definition at line 206 of file mergepostlist.cc.

References Assert, current, LOGCALL, plists, and RETURN.

◆ get_wdf()

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

Return the wdf for the document at the current position.

The default implementation throws Xapian::UnimplementedError.

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 79 of file mergepostlist.cc.

References current, LOGCALL, plists, and RETURN.

◆ get_weight()

double MergePostList::get_weight ( ) const
virtual

Return the weight contribution for the current position.

Implements Xapian::PostingIterator::Internal.

Definition at line 135 of file mergepostlist.cc.

References Assert, current, LOGCALL, plists, and RETURN.

◆ next()

PostList * MergePostList::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 48 of file mergepostlist.cc.

References at_end(), current, LOGCALL, LOGVALUE, matcher, ValueStreamDocument::new_subdb(), next_handling_prune(), plists, MultiMatch::recalc_maxweight(), RETURN, and vsdoc.

◆ operator=()

MergePostList& MergePostList::operator= ( const MergePostList )
private

◆ recalc_maxweight()

double MergePostList::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 166 of file mergepostlist.cc.

References LOGCALL, plists, RETURN, and w_max.

◆ skip_to()

PostList * MergePostList::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 68 of file mergepostlist.cc.

References LOGCALL.

Member Data Documentation

◆ current

int MergePostList::current
private

◆ matcher

MultiMatch* MergePostList::matcher
private

The object which is using this postlist to perform a match.

This object needs to be notified when the tree changes such that the maximum weights need to be recalculated.

Definition at line 52 of file mergepostlist.h.

Referenced by next().

◆ plists

vector<PostList *> MergePostList::plists
private

◆ vsdoc

ValueStreamDocument& MergePostList::vsdoc
private

Document proxy used for valuestream caching.

We need to notify this when the subdatabase changes, as then the cached valuestreams need to be cleared as they will be for the wrong subdatabase.

Definition at line 60 of file mergepostlist.h.

Referenced by next().

◆ w_max

double MergePostList::w_max
private

Definition at line 41 of file mergepostlist.h.

Referenced by get_maxweight(), and recalc_maxweight().


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