QuartzPostList Class Reference

A postlist in a quartz database. More...

#include <quartz_postlist.h>

Inheritance diagram for QuartzPostList:

[legend]Collaboration diagram for QuartzPostList:


Public Member Functions
	QuartzPostList (Xapian::Internal::RefCntPtr< const Xapian::Database::Internal > this_db_, const Btree table_, const Btree positiontable_, const string &tname)
	Default constructor.
	~QuartzPostList ()
	Destructor.
Xapian::doccount	get_termfreq () const
	Returns number of docs indexed by this term.
Xapian::docid	get_docid () const
	Returns the current docid.
Xapian::doclength	get_doclength () const
	Returns the length of current document.
Xapian::termcount	get_wdf () const
	Returns the Within Document Frequency of the term in the current document.
PositionList *	read_position_list ()
	Get the list of positions of the term in the current document.
PositionList *	open_position_list () const
	Get the list of positions of the term in the current document.
PostList *	next (Xapian::weight w_min)
	Move to the next document.
PostList *	skip_to (Xapian::docid desired_did, Xapian::weight w_min)
	Skip to next document with docid >= docid.
bool	at_end () const
	Return true if and only if we're off the end of the list.
std::string	get_description () const
	Get a description of the document.
Static Public Member Functions
static void	read_number_of_entries (const char *posptr, const char end, Xapian::termcount number_of_entries_ptr, Xapian::termcount collection_freq_ptr)
	Read the number of entries and the collection frequency.
Private Member Functions
	QuartzPostList (const QuartzPostList &)
	Copying is not allowed.
void	operator= (const QuartzPostList &)
	Assignment is not allowed.
bool	next_in_chunk ()
	Move to the next item in the chunk, if possible.
void	next_chunk ()
	Move to the next chunk.
bool	current_chunk_contains (Xapian::docid desired_did)
	Return true if the given document ID lies in the range covered by the current chunk.
void	move_to_chunk_containing (Xapian::docid desired_did)
	Move to chunk containing the specified document ID.
bool	move_forward_in_chunk_to_at_least (Xapian::docid desired_did)
	Scan forward in the current chunk for the specified document ID.
Private Attributes
Xapian::Internal::RefCntPtr< const Xapian::Database::Internal >	this_db
	The database we are searching.
const Btree *	table
	The table containing the postlist.
const Btree *	positiontable
	The table containing positionlists.
string	tname
	The termname for this postlist.
AutoPtr< Bcursor >	cursor
	Cursor pointing to current chunk of postlist.
bool	is_last_chunk
	True if this is the last chunk.
Xapian::docid	first_did_in_chunk
	The first document id in this chunk.
Xapian::docid	last_did_in_chunk
	The last document id in this chunk.
const char *	pos
	Position of iteration through current chunk.
const char *	end
	Pointer to byte after end of current chunk.
Xapian::docid	did
	Document id we're currently at.
quartz_doclen_t	doclength
	The (absolute) length of the current document.
Xapian::termcount	wdf
	The wdf of the current document.
bool	is_at_end
	Whether we've run off the end of the list yet.
bool	have_started
	Whether we've started reading the list yet.
Xapian::doccount	number_of_entries
	The number of entries in the posting list.
QuartzPositionList	positionlist
	The position list object for this posting list.

Detailed Description

A postlist in a quartz database.

Definition at line 89 of file quartz_postlist.h.

Constructor & Destructor Documentation

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

Copying is not allowed.

QuartzPostList::QuartzPostList	(	Xapian::Internal::RefCntPtr< const Xapian::Database::Internal >	this_db_,
		const Btree *	table_,
		const Btree *	positiontable_,
		const string &	tname_
	)

Default constructor.

Split into chunks. Key for first chunk is the termname (encoded as length - name). Key for subsequent chunks is the same, followed by the document ID of the first document in the chunk (encoded as length of representation in first byte, and then docid).

A chunk (except for the first chunk) contains:

1) bool - true if this is the last chunk. 2) difference between final docid in chunk and first docid. 3) wdf, then doclength of first item. 4) increment in docid to next item, followed by wdf and doclength of item 5) (4) repeatedly.

The first chunk begins with the number of entries, then the docid of the first document, then has the header of a standard chunk.

Definition at line 668 of file quartz_postlist.cc.

References cursor, DEBUGCALL, did, doclength, end, first_did_in_chunk, Xapian::Internal::RefCntPtr< T >::get(), is_at_end, is_last_chunk, last_did_in_chunk, make_key(), number_of_entries, pos, read_start_of_chunk(), read_start_of_first_chunk(), read_wdf_and_length(), tname, and wdf.

QuartzPostList::~QuartzPostList ( )

Destructor.

Definition at line 706 of file quartz_postlist.cc.

References DEBUGCALL.

Member Function Documentation

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

Assignment is not allowed.

bool QuartzPostList::next_in_chunk ( ) [private]

Move to the next item in the chunk, if possible.

If already at the end of the chunk, returns false.

Definition at line 712 of file quartz_postlist.cc.

References Assert, DEBUGCALL, did, doclength, end, last_did_in_chunk, pos, read_did_increase(), read_wdf_and_length(), RETURN, and wdf.

Referenced by move_forward_in_chunk_to_at_least(), and next().

void QuartzPostList::next_chunk ( ) [private]

Move to the next chunk.

If there are no more chunks in this postlist, this will set is_at_end to true.

Definition at line 729 of file quartz_postlist.cc.

References check_tname_in_key_lite(), cursor, DEBUGCALL, did, doclength, end, first_did_in_chunk, is_at_end, is_last_chunk, last_did_in_chunk, om_tostring(), pos, read_start_of_chunk(), read_wdf_and_length(), report_read_error(), tname, unpack_uint_preserving_sort(), and wdf.

Referenced by move_to_chunk_containing(), and next().

bool QuartzPostList::current_chunk_contains ( Xapian::docid desired_did ) [private]

Return true if the given document ID lies in the range covered by the current chunk.

This does not say whether the document ID is actually present. It will return false if the document ID is greater than the last document ID in the chunk, even if it is less than the first document ID in the next chunk: it is possible for no chunk to contain a particular document ID.

Definition at line 816 of file quartz_postlist.cc.

References DEBUGCALL, first_did_in_chunk, last_did_in_chunk, and RETURN.

Referenced by skip_to().

void QuartzPostList::move_to_chunk_containing ( Xapian::docid desired_did ) [private]

Move to chunk containing the specified document ID.

This moves to the chunk whose starting document ID is <= desired_did, but such that the next chunk's starting document ID is > desired_did.

It is thus possible that current_chunk_contains(desired_did) will return false after this call, since the document ID might lie after the end of this chunk, but before the start of the next chunk.

Definition at line 827 of file quartz_postlist.cc.

References Assert, check_tname_in_key_lite(), cursor, DEBUGCALL, did, doclength, end, first_did_in_chunk, is_at_end, is_last_chunk, last_did_in_chunk, make_key(), next_chunk(), number_of_entries, pos, read_start_of_chunk(), read_start_of_first_chunk(), read_wdf_and_length(), report_read_error(), tname, unpack_uint_preserving_sort(), and wdf.

Referenced by skip_to().

bool QuartzPostList::move_forward_in_chunk_to_at_least ( Xapian::docid desired_did ) [private]

Scan forward in the current chunk for the specified document ID.

This is particularly efficient if the desired document ID is greater than the last in the chunk - it then skips straight to the end.

Returns:: true if we moved to a valid document, false if we reached the end of the chunk.

Definition at line 878 of file quartz_postlist.cc.

References DEBUGCALL, did, end, last_did_in_chunk, next_in_chunk(), pos, and RETURN.

Referenced by skip_to().

Xapian::doccount QuartzPostList::get_termfreq ( ) const [inline, virtual]

Returns number of docs indexed by this term.

This is the length of the postlist.

Implements LeafPostList.

Definition at line 209 of file quartz_postlist.h.

Xapian::docid QuartzPostList::get_docid ( ) const [inline, virtual]

Returns the current docid.

Implements Xapian::PostingIterator::Internal.

Definition at line 212 of file quartz_postlist.h.

References Assert.

Xapian::doclength QuartzPostList::get_doclength ( ) const [inline, virtual]

Returns the length of current document.

Implements Xapian::PostingIterator::Internal.

Definition at line 215 of file quartz_postlist.h.

References Assert.

Xapian::termcount QuartzPostList::get_wdf ( ) const [inline, virtual]

Returns the Within Document Frequency of the term in the current document.

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 223 of file quartz_postlist.h.

References Assert.

PositionList * QuartzPostList::read_position_list ( ) [virtual]

Get the list of positions of the term in the current document.

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 775 of file quartz_postlist.cc.

References DEBUGCALL, did, positionlist, positiontable, QuartzPositionList::read_data(), RETURN, and tname.

PositionList * QuartzPostList::open_position_list ( ) const [virtual]

Get the list of positions of the term in the current document.

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 785 of file quartz_postlist.cc.

References DEBUGCALL, did, positiontable, AutoPtr< _Tp >::release(), RETURN, and tname.

PostList * QuartzPostList::next ( Xapian::weight w_min ) [virtual]

Move to the next document.

Implements Xapian::PostingIterator::Internal.

Definition at line 796 of file quartz_postlist.cc.

References DEBUGCALL, DEBUGLINE, did, doclength, have_started, is_at_end, next_chunk(), next_in_chunk(), om_tostring(), RETURN, and wdf.

PostList * QuartzPostList::skip_to	(	Xapian::docid	desired_did,
		Xapian::weight	w_min
	)			`[virtual]`

Skip to next document with docid >= docid.

Implements Xapian::PostingIterator::Internal.

Definition at line 896 of file quartz_postlist.cc.

References Assert, current_chunk_contains(), DEBUGCALL, DEBUGLINE, did, doclength, have_started, is_at_end, move_forward_in_chunk_to_at_least(), move_to_chunk_containing(), om_tostring(), RETURN, and wdf.

bool QuartzPostList::at_end ( ) const [inline, virtual]

Return true if and only if we're off the end of the list.

Implements Xapian::PostingIterator::Internal.

Definition at line 240 of file quartz_postlist.h.

string QuartzPostList::get_description ( ) const [virtual]

Get a description of the document.

Implements Xapian::PostingIterator::Internal.

Definition at line 933 of file quartz_postlist.cc.

References number_of_entries, om_tostring(), and tname.

void QuartzPostList::read_number_of_entries	(	const char **	posptr,
		const char *	end,
		Xapian::termcount *	number_of_entries_ptr,
		Xapian::termcount *	collection_freq_ptr
	)			`[static]`