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/*
* Copyright (C) 2007-2008, 2010 by the Widelands Development Team
*
* 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 Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#ifndef WL_LOGIC_MAPDIFFERENCEREGION_H
#define WL_LOGIC_MAPDIFFERENCEREGION_H
#include "logic/map.h"
namespace Widelands {
/// Producer/Coroutine struct that iterates over the set of nodes that is the
/// difference between the areas A and B around neighboring nodes a and b. The
/// constructor takes a Direction parameter, which is the walking direction
/// when going from a to b.
///
/// It first iterates over the set of nodes that are in A but not in B. When
/// that iteration is completed (advance has returned false),
/// move_to_other_side can be called to prepare the region for iterating over
/// the set of nodes in B but not in A. (Because of symmetry, it is after that
/// iteration again possible to call move_to_other_side to iterate over the
/// nodes that are in A but not in B again, and so on.)
///
/// \note The order in which nodes are returned is not guarantueed.
template <typename AreaType = Area<>> struct MapDifferenceRegion {
MapDifferenceRegion(const Map& map, AreaType area, Direction direction)
: area_(area), remaining_in_edge_(area.radius), passed_corner_(false) {
assert(1 <= direction);
assert(direction <= 6);
--direction;
if (!direction)
direction = 6;
--direction;
if (!direction)
direction = 6;
switch (direction) {
#define DIRECTION_CASE(dir, neighbour_function) \
case dir: \
for (; area.radius; --area.radius) \
map.neighbour_function(area_, &area_); \
break;
DIRECTION_CASE(WALK_NW, get_tln);
DIRECTION_CASE(WALK_NE, get_trn);
DIRECTION_CASE(WALK_E, get_rn);
DIRECTION_CASE(WALK_SE, get_brn);
DIRECTION_CASE(WALK_SW, get_bln);
DIRECTION_CASE(WALK_W, get_ln);
#undef DIRECTION_CASE
}
--direction;
if (!direction)
direction = 6;
--direction;
if (!direction)
direction = 6;
direction_ = direction;
}
typename AreaType::CoordsType& location() const {
return area_;
}
/**
* Moves on to the next location. The return value indicates whether the new
* location has not yet been reached during this iteration. Note that when
* the area is so large that it overlaps itself because of wrapping, the same
* location may be reached several times during an iteration, while advance
* keeps returning true. When finally advance returns false, it means that
* the iteration is done.
*/
bool advance(const Map& map);
void move_to_other_side(const Map& map);
typename AreaType::RadiusType radius() const {
return area_.radius;
}
private:
AreaType area_;
typename AreaType::RadiusType remaining_in_edge_;
bool passed_corner_;
Direction direction_;
};
}
#endif // end of include guard: WL_LOGIC_MAPDIFFERENCEREGION_H
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