MergePostList Class Reference

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

#include <mergepostlist.h>

Inheritance diagram for MergePostList:

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Collaboration diagram for MergePostList:

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List of all members.

Public Member Functions
Xapian::termcount	get_wdf () const
	Return the wdf for the document at the current position.
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.
Xapian::docid	get_docid () const
	Return the current docid.
Xapian::weight	get_weight () const
	Return the weight contribution for the current position.
const string *	get_collapse_key () const
	If the collapse key is already known, return it.
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.
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.
Xapian::termcount	count_matching_subqs () const
	Count the number of leaf subqueries which match at the current position.
	MergePostList (const std::vector< PostList * > &plists_, MultiMatch *matcher_, ValueStreamDocument &vsdoc_, Xapian::ErrorHandler *errorhandler_)
	~MergePostList ()
Private Member Functions
	MergePostList (const MergePostList &)
MergePostList &	operator= (const MergePostList &)
Private Attributes
Xapian::weight	w_max
vector< PostList * >	plists
int	current
MultiMatch *	matcher
	The object which is using this postlist to perform a match.
ValueStreamDocument &	vsdoc
	Document proxy used for valuestream caching.
Xapian::ErrorHandler *	errorhandler

---

Detailed Description

A postlist comprising postlists from different databases merged together.

Definition at line 34 of file mergepostlist.h.

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Constructor & Destructor Documentation

MergePostList::MergePostList

(

const MergePostList &

)

[private]

MergePostList::MergePostList	(	const std::vector< PostList * > &	plists_,
		MultiMatch *	matcher_,
		ValueStreamDocument &	vsdoc_,
		Xapian::ErrorHandler *	errorhandler_
	)			[inline]

Definition at line 89 of file mergepostlist.h.

MergePostList::~MergePostList

(

)

Definition at line 37 of file mergepostlist.cc.

References LOGCALL_VOID, and plists.

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Member Function Documentation

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 199 of file mergepostlist.cc.

References Assert, current, LOGCALL, and plists.

Referenced by next().

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 226 of file mergepostlist.cc.

References current, LOGCALL, plists, and RETURN.

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 154 of file mergepostlist.cc.

References Assert, current, LOGCALL, and plists.

string MergePostList::get_description

(

)

const [virtual]

Return a string description of this object.

Implements Xapian::PostingIterator::Internal.

Definition at line 207 of file mergepostlist.cc.

References plists.

Xapian::docid MergePostList::get_docid

(

)

const [virtual]

Return the current docid.

Implements Xapian::PostingIterator::Internal.

Definition at line 136 of file mergepostlist.cc.

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

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 218 of file mergepostlist.cc.

References Assert, current, LOGCALL, and plists.

Xapian::weight MergePostList::get_maxweight

(

)

const [virtual]

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

Implements Xapian::PostingIterator::Internal.

Definition at line 162 of file mergepostlist.cc.

References LOGCALL, and w_max.

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 123 of file mergepostlist.cc.

References LOGCALL, and plists.

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 97 of file mergepostlist.cc.

References LOGCALL, and plists.

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 110 of file mergepostlist.cc.

References LOGCALL, and plists.

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 90 of file mergepostlist.cc.

References current, LOGCALL, plists, and RETURN.

Xapian::weight MergePostList::get_weight

(

)

const [virtual]

Return the weight contribution for the current position.

Implements Xapian::PostingIterator::Internal.

Definition at line 146 of file mergepostlist.cc.

References Assert, current, LOGCALL, and plists.

PostList * MergePostList::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 47 of file mergepostlist.cc.

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

MergePostList& MergePostList::operator=

(

const MergePostList &

)

[private]

Xapian::weight 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 169 of file mergepostlist.cc.

References current, errorhandler, LOGCALL, LOGLINE, plists, and w_max.

PostList * MergePostList::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 79 of file mergepostlist.cc.

References LOGCALL.

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Member Data Documentation

int MergePostList::current [private]

Definition at line 44 of file mergepostlist.h.

Referenced by at_end(), count_matching_subqs(), get_collapse_key(), get_docid(), get_doclength(), get_wdf(), get_weight(), next(), and recalc_maxweight().

Xapian::ErrorHandler* MergePostList::errorhandler [private]

Definition at line 61 of file mergepostlist.h.

Referenced by next(), and recalc_maxweight().

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 51 of file mergepostlist.h.

Referenced by next().

vector<PostList *> MergePostList::plists [private]

Definition at line 42 of file mergepostlist.h.

Referenced by at_end(), count_matching_subqs(), get_collapse_key(), get_description(), get_docid(), get_doclength(), get_termfreq_est(), get_termfreq_max(), get_termfreq_min(), get_wdf(), get_weight(), next(), recalc_maxweight(), and ~MergePostList().

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 59 of file mergepostlist.h.

Referenced by next().

Xapian::weight MergePostList::w_max [private]

Definition at line 40 of file mergepostlist.h.

Referenced by get_maxweight(), and recalc_maxweight().

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

• matcher/mergepostlist.h
• matcher/mergepostlist.cc