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/** @file nearpostlist.h
* @brief Return docs containing terms within a specified window.
*
* Copyright (C) 2006,2015 Olly Betts
* Copyright (C) 2009 Lemur Consulting Ltd
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef XAPIAN_INCLUDED_NEARPOSTLIST_H
#define XAPIAN_INCLUDED_NEARPOSTLIST_H
#include "selectpostlist.h"
#include <vector>
/** Postlist which matches terms occurring within a specified window.
*
* NearPostList only returns a posting for documents contains all the terms
* (this part is implemented using an AndPostList) and additionally the terms
* occur somewhere in the document within a specified number of term
* positions.
*
* The weight of a posting is the sum of the weights of the
* sub-postings (just like an AndPostList).
*/
class NearPostList : public SelectPostList {
Xapian::termpos window;
std::vector<PostList*> terms;
PositionList ** poslists;
/// Test if the current document contains the terms within the window.
bool test_doc();
public:
NearPostList(PostList *source_,
Xapian::termpos window_,
const std::vector<PostList*>::const_iterator &terms_begin,
const std::vector<PostList*>::const_iterator &terms_end);
~NearPostList();
Xapian::termcount get_wdf() const;
Xapian::doccount get_termfreq_est() const;
TermFreqs get_termfreq_est_using_stats(
const Xapian::Weight::Internal & stats) const;
std::string get_description() const;
};
#endif
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