N-way AND postlist. More...

#include <andpostlist.h>

Inheritance diagram for AndPostList:

Collaboration diagram for AndPostList:

Classes
struct	ComparePostListTermFreqAscending
	Comparison functor which orders PostList* by ascending get_termfreq(). More...

Public Member Functions
template<class RandomItor >
	AndPostList (RandomItor pl_begin, RandomItor pl_end, PostListTree *matcher_)
	Construct from 2 random-access iterators to a container of PostList* and a pointer to the matcher. More...

	AndPostList (PostList l, PostList r, double lmax, double rmax, PostListTree *matcher_, Xapian::doccount termfreq_)
	Construct as the decay product of an OrPostList or AndMaybePostList. More...

	~AndPostList ()

Xapian::docid	get_docid () const
	Return the current docid. More...

double	get_weight (Xapian::termcount doclen, Xapian::termcount unique_terms, Xapian::termcount wdfdocmax) 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...

PostList *	next (double w_min)
	Advance the current position to the next document in the postlist. More...

PostList *	skip_to (Xapian::docid, double w_min)
	Skip forward to the specified docid. More...

void	get_docid_range (Xapian::docid &first, Xapian::docid &last) const
	Get the bounds on the range of docids this PostList can return. More...

std::string	get_description () const
	Return a string description of this object. More...

Xapian::termcount	get_wdf () const
	Get the within-document frequency. More...

Xapian::termcount	count_matching_subqs () const
	Count the number of leaf subqueries which match at the current position. More...

void	gather_position_lists (OrPositionList *orposlist)
	Gather PositionList* objects for a subtree. More...

Public Member Functions inherited from Xapian::Internal::PostList
virtual	~PostList ()
	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...

Xapian::doccount	get_termfreq () const
	Get an estimate of the number of documents this PostList will return. More...

virtual PositionList *	read_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 PositionList *	open_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 PostList *	check (Xapian::docid did, double w_min, bool &valid)
	Check if the specified docid occurs in this postlist. More...

PostList *	next ()
	Advance the current position to the next document in the postlist. More...

PostList *	skip_to (Xapian::docid did)
	Skip forward to the specified docid. More...

Private Member Functions
AndPostList &	operator= (const AndPostList &)=delete
	Don't allow assignment. More...

	AndPostList (const AndPostList &)=delete
	Don't allow copying. More...

double	new_min (double w_min, size_t n)
	Calculate the new minimum weight for sub-postlist n. More...

void	next_helper (size_t n, double w_min)
	Call next on a sub-postlist n, and handle any pruning. More...

void	skip_to_helper (size_t n, Xapian::docid did_min, double w_min)
	Call skip_to on a sub-postlist n, and handle any pruning. More...

void	check_helper (size_t n, Xapian::docid did_min, double w_min, bool &valid)
	Call check on a sub-postlist n, and handle any pruning. More...

void	allocate_plist_and_max_wt ()
	Allocate plist and max_wt arrays of n_kids each. More...

PostList *	find_next_match (double w_min)
	Advance the sublists to the next match. More...

Private Attributes
Xapian::docid	did = 0
	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 = nullptr
	Array of pointers to sub-postlists. More...

double *	max_wt = nullptr
	Array of maximum weights for the sub-postlists. More...

double	max_total = 0.0
	Total maximum weight (== sum of max_wt values). More...

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

Additional Inherited Members
Protected Member Functions inherited from Xapian::Internal::PostList
	PostList ()
	Only constructable as a base class for derived classes. More...

Protected Attributes inherited from Xapian::Internal::PostList
Xapian::doccount	termfreq
	Estimate of the number of documents this PostList will return. More...

Detailed Description

N-way AND postlist.

Definition at line 32 of file andpostlist.h.

Constructor & Destructor Documentation

◆ AndPostList() [1/3]

AndPostList::AndPostList ( const AndPostList & )

privatedelete

Don't allow copying.

◆ AndPostList() [2/3]

template<class RandomItor >

AndPostList::AndPostList	(	RandomItor	pl_begin,
		RandomItor	pl_end,
		PostListTree *	matcher_
	)

inline

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

Definition at line 119 of file andpostlist.h.

References allocate_plist_and_max_wt(), Assert, Xapian::Internal::PostList::get_docid_range(), get_docid_range(), Xapian::Internal::PostList::get_termfreq(), n_kids, plist, rare, and Xapian::Internal::PostList::termfreq.

◆ AndPostList() [3/3]

AndPostList::AndPostList	(	PostList *	l,
		PostList *	r,
		double	lmax,
		double	rmax,
		PostListTree *	matcher_,
		Xapian::doccount	termfreq_
	)

inline

Construct as the decay product of an OrPostList or AndMaybePostList.

Definition at line 154 of file andpostlist.h.

References allocate_plist_and_max_wt(), Xapian::Internal::PostList::get_termfreq(), max_wt, plist, and Xapian::Internal::PostList::termfreq.

◆ ~AndPostList()

AndPostList::~AndPostList ( )

Definition at line 44 of file andpostlist.cc.

Member Function Documentation

◆ allocate_plist_and_max_wt()

void AndPostList::allocate_plist_and_max_wt ( )

private

Allocate plist and max_wt arrays of n_kids each.

Exceptions

std::bad_alloc.

Definition at line 32 of file andpostlist.cc.

Referenced by AndPostList().

◆ at_end()

bool AndPostList::at_end ( ) const

virtual

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

Implements Xapian::Internal::PostList.

Definition at line 75 of file andpostlist.cc.

◆ check_helper()

void AndPostList::check_helper	(	size_t	n,
		Xapian::docid	did_min,
		double	w_min,
		bool &	valid
	)

inlineprivate

Call check on a sub-postlist n, and handle any pruning.

Definition at line 94 of file andpostlist.h.

References Xapian::Internal::PostList::check(), PostListTree::force_recalc(), matcher, max_wt, new_min(), and plist.

◆ count_matching_subqs()

Xapian::termcount AndPostList::count_matching_subqs ( ) const

virtual

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

Reimplemented from Xapian::Internal::PostList.

Definition at line 172 of file andpostlist.cc.

◆ find_next_match()

PostList * AndPostList::find_next_match ( double w_min )

private

Advance the sublists to the next match.

Definition at line 93 of file andpostlist.cc.

References Xapian::Internal::PostList::get_docid().

◆ gather_position_lists()

void AndPostList::gather_position_lists ( OrPositionList * orposlist )

virtual

Gather PositionList* objects for a subtree.

Reimplemented from Xapian::Internal::PostList.

Definition at line 182 of file andpostlist.cc.

◆ get_description()

std::string AndPostList::get_description ( ) const

virtual

Return a string description of this object.

Implements Xapian::Internal::PostList.

Definition at line 149 of file andpostlist.cc.

◆ get_docid()

Xapian::docid AndPostList::get_docid ( ) const

virtual

Return the current docid.

Implements Xapian::Internal::PostList.

Definition at line 56 of file andpostlist.cc.

◆ get_docid_range()

void AndPostList::get_docid_range	(	Xapian::docid &	first,
		Xapian::docid &	last
	)		const

virtual

Get the bounds on the range of docids this PostList can return.

Parameters

[out]	first	Set to a lower bound on the docids that can be returned, or not changed if there's no known lower bound (other than 1).
[out]	last	Set to an upper bound on the docids that can be returned, or not changed if there's no known upper bound (other than the highest used docid).

The default implementation (PostList::get_docid_range()) does nothing, which is suitable when there's no known lower or upper bound.

Reimplemented from Xapian::Internal::PostList.

Definition at line 136 of file andpostlist.cc.

Referenced by AndPostList().

◆ get_wdf()

Xapian::termcount AndPostList::get_wdf ( ) const

virtual

Get the within-document frequency.

For AndPostlist returns the sum of the wdfs of the sub postlists.

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::Internal::PostList.

Definition at line 162 of file andpostlist.cc.

◆ get_weight()

double AndPostList::get_weight	(	Xapian::termcount	doclen,
		Xapian::termcount	unique_terms,
		Xapian::termcount	wdfdocmax
	)		const

virtual

Return the weight contribution for the current position.

Implements Xapian::Internal::PostList.

Definition at line 62 of file andpostlist.cc.

References Assert.

◆ new_min()

double AndPostList::new_min	(	double	w_min,
		size_t	n
	)

inlineprivate

Calculate the new minimum weight for sub-postlist n.

Definition at line 67 of file andpostlist.h.

References max_total, and max_wt.

Referenced by check_helper(), next_helper(), and skip_to_helper().

◆ next()

PostList * AndPostList::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_min The 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::Internal::PostList.

Definition at line 122 of file andpostlist.cc.

◆ next_helper()

void AndPostList::next_helper	(	size_t	n,
		double	w_min
	)

inlineprivate

Call next on a sub-postlist n, and handle any pruning.

Definition at line 72 of file andpostlist.h.

References PostListTree::force_recalc(), matcher, max_wt, new_min(), Xapian::Internal::PostList::next(), and plist.

◆ operator=()

AndPostList& AndPostList::operator= ( const AndPostList & )

privatedelete

Don't allow assignment.

◆ recalc_maxweight()

double AndPostList::recalc_maxweight ( )

virtual

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

The maximum weight that get_weight() can return can decrease as the match progresses (typically when the PostList tree prunes) - calling this method calculates a current upper bound.

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

Implements Xapian::Internal::PostList.

Definition at line 81 of file andpostlist.cc.

◆ skip_to()

PostList * AndPostList::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_min The 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::Internal::PostList.

Definition at line 129 of file andpostlist.cc.

◆ skip_to_helper()

void AndPostList::skip_to_helper	(	size_t	n,
		Xapian::docid	did_min,
		double	w_min
	)

inlineprivate

Call skip_to on a sub-postlist n, and handle any pruning.

Definition at line 83 of file andpostlist.h.

References PostListTree::force_recalc(), matcher, max_wt, new_min(), plist, and Xapian::Internal::PostList::skip_to().

Member Data Documentation

◆ did

Xapian::docid AndPostList::did = 0

private

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

Definition at line 49 of file andpostlist.h.

◆ matcher

PostListTree* AndPostList::matcher

private

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

Definition at line 64 of file andpostlist.h.

Referenced by check_helper(), next_helper(), and skip_to_helper().

◆ max_total

double AndPostList::max_total = 0.0

private

Total maximum weight (== sum of max_wt values).

Definition at line 61 of file andpostlist.h.

Referenced by new_min().

◆ max_wt

double* AndPostList::max_wt = nullptr

private

Array of maximum weights for the sub-postlists.

Definition at line 58 of file andpostlist.h.

Referenced by AndPostList(), check_helper(), new_min(), next_helper(), and skip_to_helper().

◆ n_kids

size_t AndPostList::n_kids

private

The number of sub-postlists.

Definition at line 52 of file andpostlist.h.

Referenced by AndPostList().

◆ plist

PostList** AndPostList::plist = nullptr

private

Array of pointers to sub-postlists.

Definition at line 55 of file andpostlist.h.

Referenced by AndPostList(), check_helper(), next_helper(), and skip_to_helper().

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

matcher/andpostlist.h
matcher/andpostlist.cc

Classes

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ AndPostList() [1/3]

◆ AndPostList() [2/3]

◆ AndPostList() [3/3]

◆ ~AndPostList()

Member Function Documentation

◆ allocate_plist_and_max_wt()

◆ at_end()

◆ check_helper()

◆ count_matching_subqs()

◆ find_next_match()

◆ gather_position_lists()

◆ get_description()

◆ get_docid()

◆ get_docid_range()

◆ get_wdf()

◆ get_weight()

◆ new_min()

◆ next()

◆ next_helper()

◆ operator=()

◆ recalc_maxweight()

◆ skip_to()

◆ skip_to_helper()

Member Data Documentation

◆ did

◆ matcher

◆ max_total

◆ max_wt

◆ n_kids

◆ plist