IXE::PostingList::const_iterator Class Reference

Inheritance diagram for IXE::PostingList::const_iterator:

List of all members.

Public Member Functions
reference	operator* ()
pointer	operator-> ()
const_iterator &	operator++ ()
	Advance a PostingList::const_iterator.
const_iterator	operator++ (int)
const_iterator &	next (DocID min)
	Advance posting list to document with DocID min.
bool	atEnd ()
size_type	size () const
void	copyHits (std::fstream &o)
	Copy hits to file.
size_type	index () const
Public Attributes
HitsCursor	hitsCursor
Protected Member Functions
	const_iterator (size_type s, byte const *p)
Protected Attributes
size_type	rest_
	rest_ contains the number of remaining elements including the current one, already read into posting (cannot be 0, which means end)
byte const *	c_
	start of next Posting (may differ from end of current one)
size_type	tablesz_
	The size of the skip list table.
size_type	size_
	The size of the PostingList (same as size_ of parent PostingList).
PostingOffset *	table_
	table_ contains pointers to posting lists of each Postings_Segment_Size element, and the DocID of the corresponding document.
value_type	posting
Size	hitlen
Friends
class	PostingList
bool	operator== (const_iterator const &i, const_iterator const &j)
bool	operator!= (const_iterator const &i, const_iterator const &j)

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Member Function Documentation

size_type IXE::PostingList::const_iterator::index

(

)

const [inline]

Returns:

the position we are now in the posting list.

References rest_, and size_.

Referenced by IXE::PostingList::remap_iterator::operator++().

PostingList::const_iterator & IXE::PostingList::const_iterator::next

(

DocID

min

)

Advance posting list to document with DocID min.

Exploit PostingOffset table_ to perform binary search and jump to start of segment containing requested posting.

Parameters:

min

the DocID of the requested posting.

References c_, operator++(), IXE::parseEptacode(), rest_, size_, table_, and tablesz_.

Referenced by IXE::PostingList::remap_iterator::operator++().

PostingList::const_iterator & IXE::PostingList::const_iterator::operator++

(

)

Advance a PostingList::const_iterator.

Returns:

a reference to itself as is standard practice for iterators.

A posting has the following format:

I[0x80{M}...0x80]OL{H}^O

that is: a DocID (I) followed by zero or more TermColors (M) surrounded by 0x80 bytes, followed by the number of occurrences in the document (O), followed by the byte length of the hitlist less O (L), followed by O hits, i.e. positions where the word occurs in document I. Each H is a document position, represented as delta increment with respect to the previous one. First word is at position 1.

See also:

Indexer::writeIndex() for full details of the index file format.

Reimplemented in IXE::PostingList::remap_iterator.

References c_, IXE::parseEptacode(), and rest_.

Referenced by next().

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Member Data Documentation

PostingOffset* IXE::PostingList::const_iterator::table_ [protected]

table_ contains pointers to posting lists of each Postings_Segment_Size element, and the DocID of the corresponding document.

This is used to perform binary search to the segment containing the posting. Thereafter the segment is scanned linearly. Ex: 0: off0, 1234 (1024th posting contains docID 1234, at offset off0) 1: off1, 2345 (2*1024th posting contains docID 2345, at offset off1) ... n: offn, NNNN ((n+1)*1024th posting contains docID NN, at offset offn)

Referenced by next(), and IXE::PostingList::remap_iterator::remap_iterator().

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

• search/ixe/Common/PostingList.h
• search/ixe/Common/PostingList.cpp