/*
  Copyright(C) 2011-2016 Brazil

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

#pragma once

#include "dat.hpp"

namespace grn {
namespace dat {

// The most significant bit represents whether or not the entry is valid.
// A valid entry stores the position of its associated key and an invalid entry
// stores the index of the next invalid entry.
class GRN_DAT_API Entry {
 public:
  Entry() : value_(0) {}

  bool is_valid() const {
    return (value_ & IS_VALID_FLAG) == IS_VALID_FLAG;
  }
  UInt32 key_pos() const {
    GRN_DAT_DEBUG_THROW_IF(!is_valid());
    return value_ & ~IS_VALID_FLAG;
  }
  UInt32 next() const {
    GRN_DAT_DEBUG_THROW_IF(is_valid());
    return value_;
  }

  void set_key_pos(UInt32 x) {
    value_ = IS_VALID_FLAG | x;
  }
  void set_next(UInt32 x) {
    value_ = x;
  }

 private:
  UInt32 value_;

  static const UInt32 IS_VALID_FLAG = 0x80000000U;
};

}  // namespace dat
}  // namespace grn
