static void EnumUnstackMoves(IList <IMove> dest, GameState state,
PickupAndPlaceMove template, int start, BoardPosition pos, int dir)
{
var targetPos = Direction.Offset(pos, dir);
if (!state.IsPositionLegal(targetPos))
{
return;
}
var stack = state.Board[targetPos.X, targetPos.Y];
var stacktop = state[targetPos];
bool flatten = false;
if (stacktop.HasValue)
{
var topstone = Piece.GetStone(stacktop.Value);
// destination stack must not have cap stone
if (topstone == Piece.Stone_Cap)
{
return;
}
// only capstone by itself may flatten standing stone
if (topstone == Piece.Stone_Standing)
{
if (template.PickUpMove.PickUpCount - start != 1)
{
return;
}
if (!template.PickUpMove.IsCapStone(start))
{
return;
}
flatten = true;
}
}
var pickupMove = template.PickUpMove;
int maxPlace = pickupMove.PickUpCount - start;
for (int i = 1; i <= maxPlace; i++)
{
for (int j = 0; j < i; j++)
{
template.AddToChain(pickupMove.GeneratePlaceFromStack(j + start, targetPos, flatten));
}
if (i + start == pickupMove.PickUpCount)
{
dest.Add(template.ShallowCopy());
}
else
{
EnumUnstackMoves(dest, state, template, start + i, targetPos, dir);
}
template.RemoveFromEnd(i);
}
}
/// <summary>
/// Enumerate all legal moves in the current board position
/// </summary>
/// <param name="dest">Destination list into which moves will be added</param>
/// <param name="game">Current game state</param>
/// <param name="moveOrder">Order in which board positions will be considered</param>
public static void EnumerateMoves(IList <IMove> dest, GameState game, IList <BoardPosition> moveOrder)
{
int player = game.Ply & 1;
if (game.Ply < 2)
{
// place enemy flat stone on empty squares
player = player ^ 1;
foreach (var pos in moveOrder)
{
if (!game[pos].HasValue)
{
dest.Add(new PlacePieceMove(Piece.MakePieceID(Piece.Stone_Flat, player), pos, true, false));
}
}
}
else
{
// place stones on empty squares
var sremain = game.StonesRemaining[player];
var cremain = game.CapRemaining[player];
foreach (var pos in moveOrder)
{
if (!game[pos].HasValue)
{
if (sremain > 0)
{
dest.Add(new PlacePieceMove(Piece.MakePieceID(Piece.Stone_Flat, player), pos, true, false));
dest.Add(new PlacePieceMove(Piece.MakePieceID(Piece.Stone_Standing, player), pos, true, false));
}
if (cremain > 0)
{
dest.Add(new PlacePieceMove(Piece.MakePieceID(Piece.Stone_Cap, player), pos, true, false));
}
}
}
// Move stacks
foreach (var pos in moveOrder)
{
var stack = game.Board[pos.X, pos.Y];
if (stack.Count == 0)
{
continue;
}
var topPiece = stack[stack.Count - 1];
var topStone = Piece.GetStone(topPiece);
if (Piece.GetPlayerID(topPiece) != player)
{
continue;
}
for (int pickupCount = 1; pickupCount <= Math.Min(stack.Count, game.Size); pickupCount++)
{
var pickupMove = new PickUpMove(pos, pickupCount, game);
var template = new PickupAndPlaceMove(pickupMove);
for (int dir = 0; dir < 4; dir++)
{
EnumUnstackMoves(dest, game, template, 0, pos, dir);
}
}
}
}
}
/// <summary>
/// Creates a shallow copy by copying the contained moves into a new list
/// </summary>
private PickupAndPlaceMove(PickupAndPlaceMove source)
: base(source.Moves)
{
}