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/** @file documentterm.h
* @brief internal class representing a term in a modified document
*/
/* Copyright 1999,2000,2001 BrightStation PLC
* Copyright 2002 Ananova Ltd
* Copyright 2003,2007 Olly Betts
*
* 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 OM_HGUARD_DOCUMENTTERM_H
#define OM_HGUARD_DOCUMENTTERM_H
#include "debuglog.h"
#include <string>
#include <vector>
#include <xapian/types.h>
using namespace std;
/// A term in a document.
class OmDocumentTerm {
public:
/** Make a new term.
*
* @param wdf_ Initial wdf.
*/
explicit OmDocumentTerm(Xapian::termcount wdf_)
: wdf(wdf_)
{
LOGCALL_CTOR(DB, "OmDocumentTerm", wdf_);
}
/** Within document frequency of the term.
* This is the number of occurrences of the term in the document.
*/
Xapian::termcount wdf;
typedef vector<Xapian::termpos> term_positions;
/** Positional information.
*
* This is a list of positions at which the term occurs in the
* document. The list is in strictly increasing order of term
* position.
*
* The positions start at 1.
*
* Note that, even if positional information is present, the WDF might
* not be equal to the length of the position list, since a term might
* occur multiple times at a single position, but will only have one
* entry in the position list for each position.
*/
term_positions positions;
/** Add a position to the position list.
*
* This adds an entry to the list of positions, unless
* there is already one for the specified position.
*
* This does not change the value of the wdf.
*
* @param tpos The position within the document at which the term
* occurs.
*/
void add_position(Xapian::termpos tpos);
/** Remove an entry from the position list.
*
* This removes an entry from the list of positions.
*
* This does not change the value of the wdf.
*
* @exception Xapian::InvalidArgumentError is thrown if the position does
* not occur in the position list.
*/
void remove_position(Xapian::termpos tpos);
/// Increase the wdf
void inc_wdf(Xapian::termcount inc) { wdf += inc; }
/// Decrease the wdf
void dec_wdf(Xapian::termcount dec) {
if (wdf <= dec) {
wdf = 0;
} else {
wdf -= dec;
}
}
/// Get the wdf
Xapian::termcount get_wdf() const { return wdf; }
/// Return a string describing this object.
string get_description() const;
};
#endif // OM_HGUARD_DOCUMENTTERM_H
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