N-way XOR postlist. More...

#include <xorpostlist.h>

Inheritance diagram for XorPostList:

Collaboration diagram for XorPostList:

Public Member Functions
template<class RandomItor >
	XorPostList (RandomItor pl_begin, RandomItor pl_end, PostListTree *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. More...

	~XorPostList ()

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...

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...

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...

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 *	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...

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

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

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

void	erase_sublist (size_t i)
	Erase a sub-postlist. 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...

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 XOR postlist.

Definition at line 31 of file xorpostlist.h.

Constructor & Destructor Documentation

◆ XorPostList() [1/2]

XorPostList::XorPostList ( const XorPostList & )

privatedelete

Don't allow copying.

◆ XorPostList() [2/2]

template<class RandomItor >

XorPostList::XorPostList	(	RandomItor	pl_begin,
		RandomItor	pl_end,
		PostListTree *	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 65 of file xorpostlist.h.

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

◆ ~XorPostList()

XorPostList::~XorPostList ( )

Definition at line 33 of file xorpostlist.cc.

Member Function Documentation

◆ at_end()

bool XorPostList::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 64 of file xorpostlist.cc.

◆ count_matching_subqs()

Xapian::termcount XorPostList::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 229 of file xorpostlist.cc.

◆ erase_sublist()

void XorPostList::erase_sublist ( size_t i )

inlineprivate

Erase a sub-postlist.

Definition at line 51 of file xorpostlist.h.

References PostListTree::force_recalc(), matcher, n_kids, and plist.

◆ get_description()

string XorPostList::get_description ( ) const

virtual

Return a string description of this object.

Implements Xapian::Internal::PostList.

Definition at line 205 of file xorpostlist.cc.

◆ get_docid()

Xapian::docid XorPostList::get_docid ( ) const

virtual

Return the current docid.

Implements Xapian::Internal::PostList.

Definition at line 44 of file xorpostlist.cc.

◆ get_docid_range()

void XorPostList::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 193 of file xorpostlist.cc.

◆ get_wdf()

Xapian::termcount XorPostList::get_wdf ( ) const

virtual

Get the within-document frequency.

For XorPostlist returns the sum of the wdfs of the matching 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 218 of file xorpostlist.cc.

◆ get_weight()

double XorPostList::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 50 of file xorpostlist.cc.

References Assert.

◆ next()

PostList * XorPostList::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 89 of file xorpostlist.cc.

References LOGCALL, Xapian::Internal::PostList::next(), RETURN, and UNSIGNED_OVERFLOW_OK.

◆ operator=()

XorPostList& XorPostList::operator= ( const XorPostList & )

privatedelete

Don't allow assignment.

◆ read_position_list()

PositionList* XorPostList::read_position_list ( )

inlinevirtual

Read the position list for the term in the current document and return a pointer to it (owned by the PostList).

The default implementation throws Xapian::UnimplementedError.

Reimplemented from Xapian::Internal::PostList.

Definition at line 98 of file xorpostlist.h.

◆ recalc_maxweight()

double XorPostList::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 70 of file xorpostlist.cc.

References LOGCALL, and RETURN.

◆ skip_to()

PostList * XorPostList::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 143 of file xorpostlist.cc.

References AssertEq, LOGCALL, RETURN, and Xapian::Internal::PostList::skip_to().

Member Data Documentation

◆ did

Xapian::docid XorPostList::did = 0

private

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

Definition at line 39 of file xorpostlist.h.

◆ matcher

PostListTree* XorPostList::matcher

private

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

Definition at line 48 of file xorpostlist.h.

Referenced by erase_sublist().

◆ n_kids

size_t XorPostList::n_kids

private

The number of sub-postlists.

Definition at line 42 of file xorpostlist.h.

Referenced by erase_sublist(), and XorPostList().

◆ plist

PostList** XorPostList::plist = nullptr

private

Array of pointers to sub-postlists.

Definition at line 45 of file xorpostlist.h.

Referenced by erase_sublist(), and XorPostList().

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

matcher/xorpostlist.h
matcher/xorpostlist.cc

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ XorPostList() [1/2]

◆ XorPostList() [2/2]

◆ ~XorPostList()

Member Function Documentation

◆ at_end()

◆ count_matching_subqs()

◆ erase_sublist()

◆ get_description()

◆ get_docid()

◆ get_docid_range()

◆ get_wdf()

◆ get_weight()

◆ next()

◆ operator=()

◆ read_position_list()

◆ recalc_maxweight()

◆ skip_to()

Member Data Documentation

◆ did

◆ matcher

◆ n_kids

◆ plist