LTP GCOV extension - code coverage report
Current view: | directory - usr/include/xapian - postingiterator.h
Test: | lcov.info
Date: | 2008-08-14 |  | Instrumented lines: | 2
Code covered: | 100.0 % |  | Executed lines: | 2

           1                 : /** \file postingiterator.h
           2                 :  * \brief Classes for iterating through posting lists
           3                 :  */
           4                 : /* Copyright 1999,2000,2001 BrightStation PLC
           5                 :  * Copyright 2002 Ananova Ltd
           6                 :  * Copyright 2003,2004,2005,2007 Olly Betts
           7                 :  *
           8                 :  * This program is free software; you can redistribute it and/or
           9                 :  * modify it under the terms of the GNU General Public License as
          10                 :  * published by the Free Software Foundation; either version 2 of the
          11                 :  * License, or (at your option) any later version.
          12                 :  *
          13                 :  * This program is distributed in the hope that it will be useful,
          14                 :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
          15                 :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
          16                 :  * GNU General Public License for more details.
          17                 :  *
          18                 :  * You should have received a copy of the GNU General Public License
          19                 :  * along with this program; if not, write to the Free Software
          20                 :  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
          21                 :  * USA
          22                 :  */
          23                 :
          24                 : #ifndef XAPIAN_INCLUDED_POSTINGITERATOR_H
          25                 : #define XAPIAN_INCLUDED_POSTINGITERATOR_H
          26                 :
          27                 : #include <iterator>
          28                 : #include <string>
          29                 :
          30                 : #include <xapian/base.h>
          31                 : #include <xapian/types.h>
          32                 : #include <xapian/positioniterator.h>
          33                 : #include <xapian/visibility.h>
          34                 :
          35                 : namespace Xapian {
          36                 :
          37                 : class Database;
          38                 :
          39                 : /** @internal A wrapper class for a docid which returns the docid if
          40                 :  *  dereferenced with *.  We need this to implement input_iterator semantics.
          41                 :  */
          42                 : class DocIDWrapper {
          43                 :     private:
          44                 :         docid did;
          45                 :     public:
          46                 :         explicit DocIDWrapper(docid did_) : did(did_) { }
          47                 :         docid operator*() const { return did; }
          48                 : };
          49                 :
          50                 : /** An iterator pointing to items in a list of postings.
          51                 :  */
          52                 : class XAPIAN_VISIBILITY_DEFAULT PostingIterator {
          53                 :     public:
          54                 :         class Internal;
          55                 :         /// @private @internal Reference counted internals.
          56                 :         Xapian::Internal::RefCntPtr<Internal> internal;
          57                 :
          58                 :     private:
          59                 :         friend class Database; // So Database can construct us
          60                 :
          61                 :         explicit PostingIterator(Internal *internal_);
          62                 :
          63                 :     public:
          64                 :         friend bool operator==(const PostingIterator &a,
          65                 :                                const PostingIterator &b);
          66                 :
          67                 :         /// Default constructor - for declaring an uninitialised iterator
          68                 :         PostingIterator();
          69                 :
          70                 :         /// Destructor
          71                 :         ~PostingIterator();
          72                 :
          73                 :         /** Copying is allowed.  The internals are reference counted, so
          74                 :          *  copying is also cheap.
          75                 :          */
          76                 :         PostingIterator(const PostingIterator &other);
          77                 :
          78                 :         /** Assignment is allowed.  The internals are reference counted,
          79                 :          *  so assignment is also cheap.
          80                 :          */
          81                 :         void operator=(const PostingIterator &other);
          82                 :
          83                 :         PostingIterator & operator++();
          84                 :
          85                 :         DocIDWrapper operator++(int) {
          86                 :             Xapian::docid tmp = **this;
          87                 :             operator++();
          88                 :             return DocIDWrapper(tmp);
          89                 :         }
          90                 :
          91                 :         /** Skip the iterator to document did, or the first document after did
          92                 :          *  if did isn't in the list of documents being iterated.
          93                 :          */
          94                 :         void skip_to(Xapian::docid did);
          95                 :
          96                 : // Get the weight of the posting at the current position: will
          97                 : // need to set a weight object for this to work.
          98                 : // Xapian::weight get_weight() const;
          99                 :
         100                 :         /// Get the document id at the current position in the postlist.
         101                 :         Xapian::docid operator *() const;
         102                 :
         103                 :         /** Get the length of the document at the current position in the
         104                 :          *  postlist.
         105                 :          *
         106                 :          *  This information may be stored in the postlist, in which case
         107                 :          *  this lookup should be extremely fast (indeed, not require further
         108                 :          *  disk access).  If the information is not present in the postlist,
         109                 :          *  it will be retrieved from the database, at a greater performance
         110                 :          *  cost.
         111                 :          */
         112                 :         Xapian::doclength get_doclength() const;
         113                 :
         114                 :         /** Get the within document frequency of the document at the
         115                 :          *  current position in the postlist.
         116                 :          */
         117                 :         Xapian::termcount get_wdf() const;
         118                 :
         119                 :         /** Return PositionIterator pointing to start of positionlist for
         120                 :          *  current document.
         121                 :          */
         122                 :         PositionIterator positionlist_begin() const;
         123                 :
         124                 :         /** Return PositionIterator pointing to end of positionlist for
         125                 :          *  current document.
         126                 :          */
         127                 :         PositionIterator positionlist_end() const {
         128                 :             return PositionIterator(NULL);
         129                 :         }
         130                 :
         131                 :         // Don't expose these methods here.  A container iterator doesn't
         132                 :         // provide a method to find the size of the container...
         133                 :         // Xapian::doccount get_termfreq() const;
         134                 :         // Xapian::termcount get_collection_freq() const;
         135                 :
         136                 :         /// Return a string describing this object.
         137                 :         std::string get_description() const;
         138                 :
         139                 :         /// Allow use as an STL iterator
         140                 :         //@{
         141                 :         typedef std::input_iterator_tag iterator_category;
         142                 :         typedef Xapian::docid value_type;
         143                 :         typedef Xapian::doccount_diff difference_type;
         144                 :         typedef Xapian::docid * pointer;
         145                 :         typedef Xapian::docid & reference;
         146                 :         //@}
         147                 : };
         148                 :
         149                 : /// Test equality of two PostingIterators
         150              10 : inline bool operator==(const PostingIterator &a, const PostingIterator &b)
         151                 : {
         152              10 :     return (a.internal.get() == b.internal.get());
         153                 : }
         154                 :
         155                 : /// Test inequality of two PostingIterators
         156                 : inline bool operator!=(const PostingIterator &a, const PostingIterator &b)
         157                 : {
         158                 :     return !(a == b);
         159                 : }
         160                 :
         161                 : }
         162                 :
         163                 : #endif /* XAPIAN_INCLUDED_POSTINGITERATOR_H */

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