MultiAndPostList Class Reference

N-way AND postlist. More...

#include <multiandpostlist.h>

Inheritance diagram for MultiAndPostList:

[legend]Collaboration diagram for MultiAndPostList:


Public Member Functions
template<class RandomItor>
	MultiAndPostList (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.
	~MultiAndPostList ()
Xapian::doccount	get_termfreq_min () const
	Get a lower bound on the number of documents indexed by this term.
Xapian::doccount	get_termfreq_max () const
	Get an upper bound on the number of documents indexed by this term.
Xapian::doccount	get_termfreq_est () const
	Get an estimate of the number of documents indexed by this term.
Xapian::weight	get_maxweight () const
	Return an upper bound on what get_weight() can return.
Xapian::docid	get_docid () const
	Return the current docid.
Xapian::doclength	get_doclength () const
	Return the length of current document.
Xapian::weight	get_weight () const
	Return the weight contribution for the current position.
bool	at_end () const
	Return true if the current position is past the last entry in this list.
Xapian::weight	recalc_maxweight ()
	Recalculate the upper bound on what get_weight() can return.
Internal *	next (Xapian::weight w_min)
	Advance the current position to the next document in the postlist.
Internal *	skip_to (Xapian::docid, Xapian::weight w_min)
	Skip forward to the specified docid.
std::string	get_description () const
	Return a string description of this object.
virtual Xapian::termcount	get_wdf () const
	get_wdf() for MultiAndPostlists returns the sum of the wdfs of the sub postlists.
Private Member Functions
void	operator= (const MultiAndPostList &)
	Don't allow assignment.
	MultiAndPostList (const MultiAndPostList &)
	Don't allow copying.
Xapian::weight	new_min (Xapian::weight w_min, size_t n)
	Calculate the new minimum weight for sub-postlist n.
void	next_helper (size_t n, Xapian::weight w_min)
	Call next on a sub-postlist n, and handle any pruning.
void	skip_to_helper (size_t n, Xapian::docid did_min, Xapian::weight w_min)
	Call skip_to on a sub-postlist n, and handle any pruning.
void	check_helper (size_t n, Xapian::docid did_min, Xapian::weight w_min, bool &valid)
	Call check on a sub-postlist n, and handle any pruning.
PostList *	find_next_match (Xapian::weight w_min)
	Advance the sublists to the next match.
Private Attributes
Xapian::docid	did
	The current docid, or zero if we haven't started or are at_end.
size_t	n_kids
	The number of sub-postlists.
PostList **	plist
	Array of pointers to sub-postlists.
Xapian::weight *	max_wt
	Array of maximum weights for the sub-postlists.
Xapian::weight	max_total
	Total maximum weight (== sum of max_wt values).
Xapian::doccount	db_size
	The number of documents in the database.
MultiMatch *	matcher
	Pointer to the matcher object, so we can report pruning.
Classes
struct	ComparePostListTermFreqAscending
	Comparison functor which orders PostList* by ascending get_termfreq_est(). More...

Detailed Description

N-way AND postlist.

Definition at line 28 of file multiandpostlist.h.

Constructor & Destructor Documentation

MultiAndPostList::MultiAndPostList ( const MultiAndPostList & ) [private]

Don't allow copying.

template<class RandomItor>

MultiAndPostList::MultiAndPostList	(	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 109 of file multiandpostlist.h.

References max_wt, n_kids, and plist.

MultiAndPostList::~MultiAndPostList ( )

Definition at line 26 of file multiandpostlist.cc.

References max_wt, n_kids, and plist.

Member Function Documentation

void MultiAndPostList::operator= ( const MultiAndPostList & ) [private]

Don't allow assignment.

Xapian::weight MultiAndPostList::new_min	(	Xapian::weight	w_min,
		size_t	n
	)			`[inline, private]`

Calculate the new minimum weight for sub-postlist n.

Definition at line 66 of file multiandpostlist.h.

References max_total, and max_wt.

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

void MultiAndPostList::next_helper	(	size_t	n,
		Xapian::weight	w_min
	)			`[inline, private]`

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

Definition at line 71 of file multiandpostlist.h.

References matcher, new_min(), Xapian::PostingIterator::Internal::next(), plist, and MultiMatch::recalc_maxweight().

Referenced by find_next_match(), and next().

void MultiAndPostList::skip_to_helper	(	size_t	n,
		Xapian::docid	did_min,
		Xapian::weight	w_min
	)			`[inline, private]`

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

Definition at line 81 of file multiandpostlist.h.

References matcher, new_min(), plist, MultiMatch::recalc_maxweight(), and Xapian::PostingIterator::Internal::skip_to().

Referenced by find_next_match(), and skip_to().

void MultiAndPostList::check_helper	(	size_t	n,
		Xapian::docid	did_min,
		Xapian::weight	w_min,
		bool &	valid
	)			`[inline, private]`

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

Definition at line 91 of file multiandpostlist.h.

References Xapian::PostingIterator::Internal::check(), matcher, new_min(), plist, and MultiMatch::recalc_maxweight().

Referenced by find_next_match().

PostList * MultiAndPostList::find_next_match ( Xapian::weight w_min ) [private]

Advance the sublists to the next match.

Definition at line 140 of file multiandpostlist.cc.

References at_end(), check_helper(), did, Xapian::PostingIterator::Internal::get_docid(), n_kids, next_helper(), plist, and skip_to_helper().

Referenced by next(), and skip_to().

Xapian::doccount MultiAndPostList::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 38 of file multiandpostlist.cc.

References AssertParanoid, db_size, get_termfreq_est(), Xapian::PostingIterator::Internal::get_termfreq_min(), n_kids, and plist.

Xapian::doccount MultiAndPostList::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 63 of file multiandpostlist.cc.

References Xapian::PostingIterator::Internal::get_termfreq_max(), n_kids, and plist.

Xapian::doccount MultiAndPostList::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 75 of file multiandpostlist.cc.

References db_size, n_kids, and plist.

Referenced by get_termfreq_min().

Xapian::weight MultiAndPostList::get_maxweight ( ) const [virtual]

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

Implements Xapian::PostingIterator::Internal.

Definition at line 88 of file multiandpostlist.cc.

References max_total.

Xapian::docid MultiAndPostList::get_docid ( ) const [virtual]

Return the current docid.

Implements Xapian::PostingIterator::Internal.

Definition at line 94 of file multiandpostlist.cc.

References did.

Xapian::doclength MultiAndPostList::get_doclength ( ) const [virtual]

Return the length of current document.

Implements Xapian::PostingIterator::Internal.

Definition at line 100 of file multiandpostlist.cc.

References Assert, AssertEqDouble, did, Xapian::PostingIterator::Internal::get_doclength(), n_kids, and plist.

Xapian::weight MultiAndPostList::get_weight ( ) const [virtual]

Return the weight contribution for the current position.

Implements Xapian::PostingIterator::Internal.

Definition at line 111 of file multiandpostlist.cc.

References Assert, did, n_kids, and plist.

bool MultiAndPostList::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 122 of file multiandpostlist.cc.

References did.

Referenced by find_next_match().

Xapian::weight MultiAndPostList::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.

Implements Xapian::PostingIterator::Internal.

Definition at line 128 of file multiandpostlist.cc.

References max_total, max_wt, n_kids, and plist.

PostList * MultiAndPostList::next ( Xapian::weight 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() 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::PostingIterator::Internal.

Definition at line 169 of file multiandpostlist.cc.

References find_next_match(), and next_helper().

PostList * MultiAndPostList::skip_to	(	Xapian::docid	,
		Xapian::weight	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::PostingIterator::Internal.

Definition at line 176 of file multiandpostlist.cc.

References find_next_match(), and skip_to_helper().

std::string MultiAndPostList::get_description ( ) const [virtual]

Return a string description of this object.

Implements Xapian::PostingIterator::Internal.

Definition at line 183 of file multiandpostlist.cc.

References Xapian::PostingIterator::Internal::get_description(), n_kids, and plist.

Xapian::termcount MultiAndPostList::get_wdf ( ) const [virtual]

get_wdf() for MultiAndPostlists 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::PostingIterator::Internal.

Definition at line 196 of file multiandpostlist.cc.

References n_kids, and plist.