chert_synonym.h

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/* Copyright (C) 2005,2007,2008,2009,2011 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 XAPIAN_INCLUDED_CHERT_SYNONYM_H
#define XAPIAN_INCLUDED_CHERT_SYNONYM_H
 
#include <xapian/types.h>
 
#include "backends/alltermslist.h"
#include "backends/database.h"
#include "chert_lazytable.h"
#include "api/termlist.h"
 
#include <set>
#include <string>
 
class ChertSynonymTable : public ChertLazyTable {
    mutable std::string last_term;
 
    mutable std::set<std::string> last_synonyms;
 
  public:
    ChertSynonymTable(const std::string & dbdir, bool readonly)
        : ChertLazyTable("synonym", dbdir + "/synonym.", readonly,
                         Z_DEFAULT_STRATEGY) { }
 
    // Merge in batched-up changes.
    void merge_changes();
 
    // Discard batched-up changes.
    void discard_changes() {
        last_term.resize(0);
        last_synonyms.clear();
    }
 
    void add_synonym(const std::string & term, const std::string & synonym);
 
    void remove_synonym(const std::string & term, const std::string & synonym);
 
    void clear_synonyms(const std::string & term);
 
    TermList * open_termlist(const std::string & term);
 
    bool is_modified() const {
        return !last_term.empty() || ChertTable::is_modified();
    }
 
    void flush_db() {
        merge_changes();
        ChertTable::flush_db();
    }
 
    void cancel() {
        discard_changes();
        ChertTable::cancel();
    }
 
    // @}
};
 
class ChertCursor;
 
class ChertSynonymTermList : public AllTermsList {
    ChertSynonymTermList(const ChertSynonymTermList &);
 
    void operator=(const ChertSynonymTermList &);
 
    Xapian::Internal::intrusive_ptr<const Xapian::Database::Internal> database;
 
    ChertCursor * cursor;
 
    string prefix;
 
  public:
    ChertSynonymTermList(Xapian::Internal::intrusive_ptr<const Xapian::Database::Internal> database_,
                      ChertCursor * cursor_,
                      const string & prefix_)
            : database(database_), cursor(cursor_), prefix(prefix_)
    {
        // Position the cursor on the highest key before the first key we want,
        // so that the first call to next() will put us on the first key we
        // want.
        if (prefix.empty()) {
            cursor->find_entry(string());
        } else {
            // Seek to the first key before one with the desired prefix.
            cursor->find_entry_lt(prefix);
        }
    }
 
    ~ChertSynonymTermList();
 
    string get_termname() const;
 
    Xapian::doccount get_termfreq() const;
 
    TermList * next();
 
    TermList * skip_to(const string &tname);
 
    bool at_end() const;
};
 
#endif // XAPIAN_INCLUDED_CHERT_SYNONYM_H