AndMaybePostList Class Reference

A postlist with weights modified by another postlist. More...

#include <andmaybepostlist.h>

Inheritance diagram for AndMaybePostList:

Collaboration diagram for AndMaybePostList:

List of all members.

Public Member Functions

Xapian::doccount get_termfreq_max () const

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

Xapian::doccount get_termfreq_min () const

Get a lower 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.

TermFreqs get_termfreq_est_using_stats (const Xapian::Weight::Internal &stats) const

Get an estimate for the termfreq and reltermfreq, given the stats.

Xapian::docid get_docid () const

Return the current docid.

Xapian::weight get_weight () const

Return the weight contribution for the current position.

Xapian::weight get_maxweight () const

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

Xapian::weight recalc_maxweight ()

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

PostList * next (Xapian::weight w_min)

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

PostList * skip_to (Xapian::docid did, Xapian::weight w_min)

Skip forward to the specified docid.

bool at_end () const

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

std::string get_description () const

Return a string description of this object.

virtual Xapian::termcount get_doclength () const

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

AndMaybePostList (PostList *left_, PostList *right_, MultiMatch *matcher_, Xapian::doccount dbsize_)

AndMaybePostList (PostList *left_, PostList *right_, MultiMatch *matcher_, Xapian::doccount dbsize_, Xapian::docid lhead_, Xapian::docid rhead_)

Constructor for use by decomposing OrPostList.

PostList * sync_rhs (Xapian::weight w_min)

Synchronise the RHS to the LHS after construction.

Xapian::termcount get_wdf () const

get_wdf() for ANDMAYBE postlists returns the sum of the wdfs of the sub postlists which are at the current document - this is desirable when the ANDMAYBE is part of a synonym.

Xapian::termcount count_matching_subqs () const

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

Private Member Functions

PostList * process_next_or_skip_to (Xapian::weight w_min, PostList *ret)

Private Attributes

Xapian::doccount dbsize

Xapian::docid lhead

Xapian::docid rhead

Xapian::weight lmax

Xapian::weight rmax

Detailed Description

A postlist with weights modified by another postlist.

This postlist returns a posting if and only if it is in the left sub-postlist.

If the posting does not occur in the right postlist, the weight for the posting is simply that in the left postlist. If the posting occurs in both postlists, the weight for the posting is the sum of the weights in the sub-postlists.

This type of postlist is useful for specifying a set of terms which must appear in the query result: these terms can be specified as the left hand argument, with the rest of the query being on the right hand side, and having the effect of modifying the weights.

The postlist is also used as a "decay product" of other postlist types during the match process: when a postlist can no longer cause a document to enter the mset on its own, but can influence relative rankings, it may be combined using one of these.

Definition at line 53 of file andmaybepostlist.h.

Constructor & Destructor Documentation

AndMaybePostList::AndMaybePostList	(	PostList *	left_,
		PostList *	right_,
		MultiMatch *	matcher_,
		Xapian::doccount	dbsize_
	)			`[inline]`

Definition at line 85 of file andmaybepostlist.h.

AndMaybePostList::AndMaybePostList	(	PostList *	left_,
		PostList *	right_,
		MultiMatch *	matcher_,
		Xapian::doccount	dbsize_,
		Xapian::docid	lhead_,
		Xapian::docid	rhead_
	)			`[inline]`

Constructor for use by decomposing OrPostList.

Definition at line 96 of file andmaybepostlist.h.

References Xapian::PostingIterator::Internal::get_maxweight(), BranchPostList::l, lmax, BranchPostList::r, and rmax.

Member Function Documentation

bool AndMaybePostList::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 185 of file andmaybepostlist.cc.

References lhead, LOGCALL, and RETURN.

Xapian::termcount AndMaybePostList::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 216 of file andmaybepostlist.cc.

References Xapian::PostingIterator::Internal::count_matching_subqs(), BranchPostList::l, lhead, LOGCALL, BranchPostList::r, RETURN, and rhead.

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

Return a string description of this object.

Implements Xapian::PostingIterator::Internal.

Definition at line 192 of file andmaybepostlist.cc.

References Xapian::PostingIterator::Internal::get_description(), BranchPostList::l, and BranchPostList::r.

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

Return the current docid.

Implements Xapian::PostingIterator::Internal.

Definition at line 150 of file andmaybepostlist.cc.

References Assert, lhead, LOGCALL, and RETURN.

Xapian::termcount AndMaybePostList::get_doclength ( ) const [virtual]

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

Implements Xapian::PostingIterator::Internal.

Definition at line 199 of file andmaybepostlist.cc.

References Assert, AssertEq, Xapian::PostingIterator::Internal::get_doclength(), BranchPostList::l, lhead, LOGCALL, BranchPostList::r, RETURN, and rhead.

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

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

Implements Xapian::PostingIterator::Internal.

Definition at line 169 of file andmaybepostlist.cc.

References lmax, LOGCALL, RETURN, and rmax.

Referenced by recalc_maxweight().

Xapian::doccount AndMaybePostList::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 133 of file andmaybepostlist.cc.

References Xapian::PostingIterator::Internal::get_termfreq_est(), BranchPostList::l, LOGCALL, and RETURN.

TermFreqs AndMaybePostList::get_termfreq_est_using_stats ( const Xapian::Weight::Internal & stats ) const [virtual]

Get an estimate for the termfreq and reltermfreq, given the stats.

The frequencies may be for a combination of databases, or for just the relevant documents, so the results need not lie in the bounds given by get_termfreq_min() and get_termfreq_max().

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 141 of file andmaybepostlist.cc.

References Xapian::PostingIterator::Internal::get_termfreq_est_using_stats(), BranchPostList::l, LOGCALL, and RETURN.

Xapian::doccount AndMaybePostList::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 117 of file andmaybepostlist.cc.

References Xapian::PostingIterator::Internal::get_termfreq_max(), BranchPostList::l, LOGCALL, and RETURN.

Xapian::doccount AndMaybePostList::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 125 of file andmaybepostlist.cc.

References Xapian::PostingIterator::Internal::get_termfreq_min(), BranchPostList::l, LOGCALL, and RETURN.

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

get_wdf() for ANDMAYBE postlists returns the sum of the wdfs of the sub postlists which are at the current document - this is desirable when the ANDMAYBE is part of a synonym.

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 208 of file andmaybepostlist.cc.

References Xapian::PostingIterator::Internal::get_wdf(), BranchPostList::l, lhead, LOGCALL, BranchPostList::r, RETURN, and rhead.

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

Return the weight contribution for the current position.

Implements Xapian::PostingIterator::Internal.

Definition at line 159 of file andmaybepostlist.cc.

References Assert, Xapian::PostingIterator::Internal::get_weight(), BranchPostList::l, lhead, LOGCALL, BranchPostList::r, RETURN, and rhead.

PostList * AndMaybePostList::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 80 of file andmaybepostlist.cc.

References dbsize, BranchPostList::l, lhead, lmax, LOGCALL, LOGLINE, BranchPostList::matcher, Xapian::PostingIterator::Internal::next(), process_next_or_skip_to(), BranchPostList::r, RETURN, rhead, rmax, and skip_to_handling_prune().

PostList * AndMaybePostList::process_next_or_skip_to	(	Xapian::weight	w_min,
		PostList *	ret
	)			`[private]`

Definition at line 32 of file andmaybepostlist.cc.

References Xapian::PostingIterator::Internal::at_end(), check_handling_prune(), Xapian::PostingIterator::Internal::get_docid(), BranchPostList::handle_prune(), BranchPostList::l, lhead, lmax, LOGCALL, BranchPostList::matcher, BranchPostList::r, RETURN, and rhead.

Referenced by next(), and skip_to().

Xapian::weight AndMaybePostList::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 176 of file andmaybepostlist.cc.

References get_maxweight(), BranchPostList::l, lmax, LOGCALL, BranchPostList::r, Xapian::PostingIterator::Internal::recalc_maxweight(), RETURN, and rmax.

PostList * AndMaybePostList::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 96 of file andmaybepostlist.cc.

References dbsize, BranchPostList::l, lhead, lmax, LOGCALL, LOGLINE, BranchPostList::matcher, process_next_or_skip_to(), BranchPostList::r, RETURN, rhead, rmax, Xapian::PostingIterator::Internal::skip_to(), and skip_to_handling_prune().

PostList * AndMaybePostList::sync_rhs ( Xapian::weight w_min )

Synchronise the RHS to the LHS after construction.

Used after constructing from a decomposing OrPostList

Definition at line 61 of file andmaybepostlist.cc.

References Xapian::PostingIterator::Internal::at_end(), check_handling_prune(), Xapian::PostingIterator::Internal::get_docid(), BranchPostList::l, lhead, lmax, LOGCALL, BranchPostList::matcher, BranchPostList::r, RETURN, and rhead.

Referenced by OrPostList::check(), OrPostList::next(), and OrPostList::skip_to().

Member Data Documentation

Xapian::doccount AndMaybePostList::dbsize [private]

Definition at line 55 of file andmaybepostlist.h.

Referenced by next(), and skip_to().

Xapian::docid AndMaybePostList::lhead [private]

Definition at line 56 of file andmaybepostlist.h.

Referenced by at_end(), count_matching_subqs(), get_docid(), get_doclength(), get_wdf(), get_weight(), next(), process_next_or_skip_to(), skip_to(), and sync_rhs().

Xapian::weight AndMaybePostList::lmax [private]

Definition at line 57 of file andmaybepostlist.h.

Referenced by AndMaybePostList(), get_maxweight(), next(), process_next_or_skip_to(), recalc_maxweight(), skip_to(), and sync_rhs().

Xapian::docid AndMaybePostList::rhead [private]

Definition at line 56 of file andmaybepostlist.h.

Referenced by count_matching_subqs(), get_doclength(), get_wdf(), get_weight(), next(), process_next_or_skip_to(), skip_to(), and sync_rhs().

Xapian::weight AndMaybePostList::rmax [private]

Definition at line 57 of file andmaybepostlist.h.

Referenced by AndMaybePostList(), get_maxweight(), next(), recalc_maxweight(), and skip_to().

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

matcher/andmaybepostlist.h
matcher/andmaybepostlist.cc


Public Member Functions
Xapian::doccount	get_termfreq_max () const
	Get an upper bound on the number of documents indexed by this term.
Xapian::doccount	get_termfreq_min () const
	Get a lower 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.
TermFreqs	get_termfreq_est_using_stats (const Xapian::Weight::Internal &stats) const
	Get an estimate for the termfreq and reltermfreq, given the stats.
Xapian::docid	get_docid () const
	Return the current docid.
Xapian::weight	get_weight () const
	Return the weight contribution for the current position.
Xapian::weight	get_maxweight () const
	Return an upper bound on what get_weight() can return.
Xapian::weight	recalc_maxweight ()
	Recalculate the upper bound on what get_weight() can return.
PostList *	next (Xapian::weight w_min)
	Advance the current position to the next document in the postlist.
PostList *	skip_to (Xapian::docid did, Xapian::weight w_min)
	Skip forward to the specified docid.
bool	at_end () const
	Return true if the current position is past the last entry in this list.
std::string	get_description () const
	Return a string description of this object.
virtual Xapian::termcount	get_doclength () const
	Return the document length of the document the current term comes from.
	AndMaybePostList (PostList left_, PostList right_, MultiMatch *matcher_, Xapian::doccount dbsize_)
	AndMaybePostList (PostList left_, PostList right_, MultiMatch *matcher_, Xapian::doccount dbsize_, Xapian::docid lhead_, Xapian::docid rhead_)
	Constructor for use by decomposing OrPostList.
PostList *	sync_rhs (Xapian::weight w_min)
	Synchronise the RHS to the LHS after construction.
Xapian::termcount	get_wdf () const
	get_wdf() for ANDMAYBE postlists returns the sum of the wdfs of the sub postlists which are at the current document - this is desirable when the ANDMAYBE is part of a synonym.
Xapian::termcount	count_matching_subqs () const
	Count the number of leaf subqueries which match at the current position.
Private Member Functions
PostList *	process_next_or_skip_to (Xapian::weight w_min, PostList *ret)
Private Attributes
Xapian::doccount	dbsize
Xapian::docid	lhead
Xapian::docid	rhead
Xapian::weight	lmax
Xapian::weight	rmax