xapian-core  1.4.21
Public Member Functions | Static Public Member Functions | Private Member Functions | Private Attributes | List of all members
GlassPostList Class Reference

A postlist in a glass database. More...

#include <glass_postlist.h>

+ Inheritance diagram for GlassPostList:
+ Collaboration diagram for GlassPostList:

Public Member Functions

 GlassPostList (Xapian::Internal::intrusive_ptr< const GlassDatabase > this_db_, const string &term, bool keep_reference)
 Default constructor. More...
 
 ~GlassPostList ()
 Destructor. More...
 
LeafPostListopen_nearby_postlist (const std::string &term_) const
 Open another postlist from the same database. More...
 
bool jump_to (Xapian::docid desired_did)
 Used for looking up doclens. More...
 
Xapian::doccount get_termfreq () const
 Returns number of docs indexed by this term. More...
 
Xapian::docid get_docid () const
 Returns the current docid. More...
 
Xapian::termcount get_doclength () const
 Returns the length of current document. More...
 
Xapian::termcount get_unique_terms () const
 Returns the number of unique terms in the current document. More...
 
Xapian::termcount get_wdf () const
 Returns the Within Document Frequency of the term in the current document. More...
 
PositionListread_position_list ()
 Get the list of positions of the term in the current document. More...
 
PositionListopen_position_list () const
 Get the list of positions of the term in the current document. More...
 
PostListnext (double w_min)
 Move to the next document. More...
 
PostListskip_to (Xapian::docid desired_did, double w_min)
 Skip to next document with docid >= docid. More...
 
bool at_end () const
 Return true if and only if we're off the end of the list. More...
 
Xapian::termcount get_wdf_upper_bound () const
 
std::string get_description () const
 Get a description of the document. More...
 
- Public Member Functions inherited from LeafPostList
 ~LeafPostList ()
 
void set_termweight (const Xapian::Weight *weight_)
 Set the weighting scheme to use during matching. More...
 
double resolve_lazy_termweight (Xapian::Weight *weight_, Xapian::Weight::Internal *stats, Xapian::termcount qlen, Xapian::termcount wqf, double factor)
 
Xapian::doccount get_termfreq_min () const
 Get a lower bound on the number of documents indexed by this term. More...
 
Xapian::doccount get_termfreq_max () const
 Get an upper bound on the number of documents indexed by this term. More...
 
Xapian::doccount get_termfreq_est () const
 Get an estimate of the number of documents indexed by this term. More...
 
double get_maxweight () const
 Return an upper bound on what get_weight() can return. More...
 
double get_weight () const
 Return the weight contribution for the current position. More...
 
double recalc_maxweight ()
 Recalculate the upper bound on what get_weight() can return. More...
 
TermFreqs get_termfreq_est_using_stats (const Xapian::Weight::Internal &stats) const
 Get an estimate for the termfreq and reltermfreq, given the stats. More...
 
Xapian::termcount count_matching_subqs () const
 Count the number of leaf subqueries which match at the current position. More...
 
void gather_position_lists (OrPositionList *orposlist)
 Gather PositionList* objects for a subtree. More...
 
void set_term (const std::string &term_)
 Set the term name. More...
 
- Public Member Functions inherited from Xapian::PostingIterator::Internal
virtual ~Internal ()
 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...
 
virtual const std::string * get_sort_key () const
 
virtual const std::string * get_collapse_key () const
 If the collapse key is already known, return it. More...
 
virtual Internalcheck (Xapian::docid did, double w_min, bool &valid)
 Check if the specified docid occurs in this postlist. More...
 
Internalnext ()
 Advance the current position to the next document in the postlist. More...
 
Internalskip_to (Xapian::docid did)
 Skip forward to the specified docid. More...
 
- Public Member Functions inherited from Xapian::Internal::intrusive_base
 intrusive_base ()
 Construct with no references. More...
 

Static Public Member Functions

static void read_number_of_entries (const char **posptr, const char *end, Xapian::doccount *number_of_entries_ptr, Xapian::termcount *collection_freq_ptr)
 Read the number of entries and the collection frequency. More...
 

Private Member Functions

 GlassPostList (const GlassPostList &)
 Copying is not allowed. More...
 
void operator= (const GlassPostList &)
 Assignment is not allowed. More...
 
bool next_in_chunk ()
 Move to the next item in the chunk, if possible. More...
 
void next_chunk ()
 Move to the next chunk. More...
 
bool current_chunk_contains (Xapian::docid desired_did)
 Return true if the given document ID lies in the range covered by the current chunk. More...
 
void move_to_chunk_containing (Xapian::docid desired_did)
 Move to chunk containing the specified document ID. More...
 
bool move_forward_in_chunk_to_at_least (Xapian::docid desired_did)
 Scan forward in the current chunk for the specified document ID. More...
 
 GlassPostList (Xapian::Internal::intrusive_ptr< const GlassDatabase > this_db_, const string &term, GlassCursor *cursor_)
 
void init ()
 

Private Attributes

Xapian::Internal::intrusive_ptr< const GlassDatabasethis_db
 The database we are searching. More...
 
GlassPositionList positionlist
 The position list object for this posting list. More...
 
bool have_started
 Whether we've started reading the list yet. More...
 
bool is_last_chunk
 True if this is the last chunk. More...
 
bool is_at_end
 Whether we've run off the end of the list yet. More...
 
AutoPtr< GlassCursorcursor
 Cursor pointing to current chunk of postlist. More...
 
Xapian::docid first_did_in_chunk
 The first document id in this chunk. More...
 
Xapian::docid last_did_in_chunk
 The last document id in this chunk. More...
 
const char * pos
 Position of iteration through current chunk. More...
 
const char * end
 Pointer to byte after end of current chunk. More...
 
Xapian::docid did
 Document id we're currently at. More...
 
Xapian::termcount wdf
 The wdf of the current document. More...
 
Xapian::doccount number_of_entries
 The number of entries in the posting list. More...
 
Xapian::termcount wdf_upper_bound
 Upper bound on wdf for this postlist. More...
 

Additional Inherited Members

- Public Attributes inherited from Xapian::Internal::intrusive_base
unsigned _refs
 Reference count. More...
 
- Protected Member Functions inherited from LeafPostList
 LeafPostList (const std::string &term_)
 Only constructable as a base class for derived classes. More...
 
- Protected Member Functions inherited from Xapian::PostingIterator::Internal
 Internal ()
 Only constructable as a base class for derived classes. More...
 
- Protected Attributes inherited from LeafPostList
const Xapian::Weightweight
 
bool need_doclength
 
bool need_unique_terms
 
std::string term
 The term name for this postlist (empty for an alldocs postlist). More...
 

Detailed Description

A postlist in a glass database.

Definition at line 145 of file glass_postlist.h.

Constructor & Destructor Documentation

◆ GlassPostList() [1/3]

GlassPostList::GlassPostList ( const GlassPostList )
private

Copying is not allowed.

Referenced by open_nearby_postlist().

◆ GlassPostList() [2/3]

GlassPostList::GlassPostList ( Xapian::Internal::intrusive_ptr< const GlassDatabase this_db_,
const string &  term,
GlassCursor cursor_ 
)
private

◆ GlassPostList() [3/3]

GlassPostList::GlassPostList ( Xapian::Internal::intrusive_ptr< const GlassDatabase this_db_,
const string &  term_,
bool  keep_reference 
)

Default constructor.

The format of a postlist is:

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 for the first item. 4) increment in docid to next item, followed by wdf for the item. 5) (4) repeatedly.

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

Definition at line 698 of file glass_postlist.cc.

References Xapian::Internal::intrusive_ptr< T >::get(), init(), and LOGCALL_CTOR.

◆ ~GlassPostList()

GlassPostList::~GlassPostList ( )

Destructor.

Definition at line 756 of file glass_postlist.cc.

References LOGCALL_DTOR.

Member Function Documentation

◆ at_end()

bool GlassPostList::at_end ( ) const
inlinevirtual

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

Implements Xapian::PostingIterator::Internal.

Definition at line 300 of file glass_postlist.h.

Referenced by GlassAllDocsPostList::get_wdf().

◆ current_chunk_contains()

bool GlassPostList::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 892 of file glass_postlist.cc.

References first_did_in_chunk, last_did_in_chunk, LOGCALL, and RETURN.

Referenced by jump_to(), and skip_to().

◆ get_description()

string GlassPostList::get_description ( ) const
virtual

Get a description of the document.

Implements Xapian::PostingIterator::Internal.

Definition at line 1041 of file glass_postlist.cc.

References description_append(), number_of_entries, Xapian::Internal::str(), and LeafPostList::term.

◆ get_docid()

Xapian::docid GlassPostList::get_docid ( ) const
inlinevirtual

Returns the current docid.

Implements Xapian::PostingIterator::Internal.

Definition at line 272 of file glass_postlist.h.

References Assert.

◆ get_doclength()

Xapian::termcount GlassPostList::get_doclength ( ) const
virtual

Returns the length of current document.

Implements Xapian::PostingIterator::Internal.

Definition at line 773 of file glass_postlist.cc.

References Assert, did, Xapian::Internal::intrusive_ptr< T >::get(), GlassDatabase::get_doclength(), have_started, LOGCALL, RETURN, and this_db.

◆ get_termfreq()

Xapian::doccount GlassPostList::get_termfreq ( ) const
inlinevirtual

Returns number of docs indexed by this term.

This is the length of the postlist.

Implements LeafPostList.

Definition at line 269 of file glass_postlist.h.

◆ get_unique_terms()

Xapian::termcount GlassPostList::get_unique_terms ( ) const
virtual

Returns the number of unique terms in the current document.

Implements Xapian::PostingIterator::Internal.

Definition at line 782 of file glass_postlist.cc.

References Assert, did, Xapian::Internal::intrusive_ptr< T >::get(), GlassDatabase::get_unique_terms(), have_started, LOGCALL, RETURN, and this_db.

◆ get_wdf()

Xapian::termcount GlassPostList::get_wdf ( ) const
inlinevirtual

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

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 283 of file glass_postlist.h.

References Assert.

Referenced by GlassAllDocsPostList::get_doclength().

◆ get_wdf_upper_bound()

Xapian::termcount GlassPostList::get_wdf_upper_bound ( ) const
virtual

Implements LeafPostList.

Definition at line 1369 of file glass_postlist.cc.

References wdf_upper_bound.

◆ init()

void GlassPostList::init ( )
private

◆ jump_to()

bool GlassPostList::jump_to ( Xapian::docid  desired_did)

Used for looking up doclens.

Returns
true if docid desired_did has a document length.

Definition at line 1012 of file glass_postlist.cc.

References current_chunk_contains(), did, have_started, is_at_end, LOGCALL, move_forward_in_chunk_to_at_least(), move_to_chunk_containing(), pos, and RETURN.

◆ move_forward_in_chunk_to_at_least()

bool GlassPostList::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 951 of file glass_postlist.cc.

References Assert, did, end, last_did_in_chunk, LOGCALL, pos, read_did_increase(), read_wdf(), RETURN, and wdf.

Referenced by jump_to(), and skip_to().

◆ move_to_chunk_containing()

void GlassPostList::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 903 of file glass_postlist.cc.

References Assert, check_tname_in_key_lite(), cursor, did, end, first_did_in_chunk, is_at_end, is_last_chunk, last_did_in_chunk, LOGCALL_VOID, GlassPostListTable::make_key(), next_chunk(), number_of_entries, pos, read_start_of_chunk(), read_start_of_first_chunk(), read_wdf(), report_read_error(), LeafPostList::term, unpack_uint_preserving_sort(), and wdf.

Referenced by jump_to(), and skip_to().

◆ next()

PostList * GlassPostList::next ( double  w_min)
virtual

Move to the next document.

Implements Xapian::PostingIterator::Internal.

Definition at line 871 of file glass_postlist.cc.

References did, have_started, is_at_end, LOGCALL, LOGLINE, next_chunk(), next_in_chunk(), RETURN, and wdf.

◆ next_chunk()

void GlassPostList::next_chunk ( )
private

◆ next_in_chunk()

bool GlassPostList::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 791 of file glass_postlist.cc.

References Assert, did, end, last_did_in_chunk, LOGCALL, pos, read_did_increase(), read_wdf(), RETURN, and wdf.

Referenced by next().

◆ open_nearby_postlist()

LeafPostList * GlassPostList::open_nearby_postlist ( const std::string &  term_) const
virtual

Open another postlist from the same database.

Parameters
term_The term to open a postlist for. If term_ is near to this postlist's term, then this can be a lot more efficient (and if it isn't very near, there's not much of a penalty). Using this method can make a wildcard expansion much more memory efficient.
Returns
The new postlist object, or NULL if not supported (in which case the caller should probably open the postlist via the database instead).

Reimplemented from LeafPostList.

Definition at line 762 of file glass_postlist.cc.

References cursor, Xapian::Internal::intrusive_ptr< T >::get(), GlassPostList(), GlassTable::is_writable(), LOGCALL, GlassDatabase::postlist_table, RETURN, and this_db.

◆ open_position_list()

PositionList * GlassPostList::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 863 of file glass_postlist.cc.

References Assert, did, Xapian::Internal::intrusive_ptr< T >::get(), LOGCALL, GlassDatabase::open_position_list(), RETURN, LeafPostList::term, and this_db.

◆ operator=()

void GlassPostList::operator= ( const GlassPostList )
private

Assignment is not allowed.

◆ read_number_of_entries()

void GlassPostList::read_number_of_entries ( const char **  posptr,
const char *  end,
Xapian::doccount number_of_entries_ptr,
Xapian::termcount collection_freq_ptr 
)
static

Read the number of entries and the collection frequency.

Read the number of entries in the posting list.

This must only be called when *posptr is pointing to the start of the first chunk of the posting list.

Definition at line 668 of file glass_postlist.cc.

References report_read_error(), and unpack_uint().

Referenced by GlassPostListTable::get_freqs(), read_start_of_first_chunk(), and GlassAllTermsList::read_termfreq().

◆ read_position_list()

PositionList * GlassPostList::read_position_list ( )
virtual

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

Reimplemented from Xapian::PostingIterator::Internal.

Definition at line 854 of file glass_postlist.cc.

References Assert, did, Xapian::Internal::intrusive_ptr< T >::get(), LOGCALL, positionlist, GlassDatabase::read_position_list(), RETURN, LeafPostList::term, and this_db.

◆ skip_to()

PostList * GlassPostList::skip_to ( Xapian::docid  desired_did,
double  w_min 
)
virtual

Member Data Documentation

◆ cursor

AutoPtr<GlassCursor> GlassPostList::cursor
private

◆ did

Xapian::docid GlassPostList::did
private

◆ end

const char* GlassPostList::end
private

◆ first_did_in_chunk

Xapian::docid GlassPostList::first_did_in_chunk
private

The first document id in this chunk.

Definition at line 168 of file glass_postlist.h.

Referenced by current_chunk_contains(), GlassPostListTable::get_chunk(), init(), move_to_chunk_containing(), and next_chunk().

◆ have_started

bool GlassPostList::have_started
private

Whether we've started reading the list yet.

Definition at line 156 of file glass_postlist.h.

Referenced by get_doclength(), get_unique_terms(), jump_to(), next(), and skip_to().

◆ is_at_end

bool GlassPostList::is_at_end
private

Whether we've run off the end of the list yet.

Definition at line 162 of file glass_postlist.h.

Referenced by init(), jump_to(), move_to_chunk_containing(), next(), next_chunk(), and skip_to().

◆ is_last_chunk

bool GlassPostList::is_last_chunk
private

True if this is the last chunk.

Definition at line 159 of file glass_postlist.h.

Referenced by GlassPostListTable::get_chunk(), init(), move_to_chunk_containing(), and next_chunk().

◆ last_did_in_chunk

Xapian::docid GlassPostList::last_did_in_chunk
private

◆ number_of_entries

Xapian::doccount GlassPostList::number_of_entries
private

The number of entries in the posting list.

Definition at line 186 of file glass_postlist.h.

Referenced by get_description(), init(), and move_to_chunk_containing().

◆ pos

const char* GlassPostList::pos
private

◆ positionlist

GlassPositionList GlassPostList::positionlist
private

The position list object for this posting list.

Definition at line 153 of file glass_postlist.h.

Referenced by read_position_list().

◆ this_db

Xapian::Internal::intrusive_ptr<const GlassDatabase> GlassPostList::this_db
private

The database we are searching.

This pointer is held so that the database doesn't get deleted before us, and also to give us access to the position_table.

Definition at line 150 of file glass_postlist.h.

Referenced by get_doclength(), get_unique_terms(), open_nearby_postlist(), open_position_list(), and read_position_list().

◆ wdf

Xapian::termcount GlassPostList::wdf
private

The wdf of the current document.

Definition at line 183 of file glass_postlist.h.

Referenced by init(), move_forward_in_chunk_to_at_least(), move_to_chunk_containing(), next(), next_chunk(), next_in_chunk(), and skip_to().

◆ wdf_upper_bound

Xapian::termcount GlassPostList::wdf_upper_bound
private

Upper bound on wdf for this postlist.

Definition at line 189 of file glass_postlist.h.

Referenced by get_wdf_upper_bound(), and init().


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