Add an origin square argument to its one method ::ray_to_square(). Pushing this
implementation down a layer means I don't have to care about the color of the
piece.
Position::default specifies the defaults for all field. Then, ::new() and
::starting() can use ..Default::default() in their implementations to avoid
having to specify empty values for all the internal structures.
This trait declares ray_to_square() which should return a BitBoard representing
a ray from a Square to another Square. The ray should include the target Square.
PlacedPiece implements this trait.
Add a field to MoveSet called special that flags special moves that should be
generated in the iter() method. This field is a u8. It only tracks castles in
the first and second bits (kingside and queenside, respectively). The move iterator
chains two maps over Option<()> that produce the kingside and queenside castle
moves.
With that done, finish the implementation of Position::player_can_castle by
adding checks for whether the squares between the rook and king are clear, and
that the king would not pass through a check. This is done with BitBoards!
Finally, implement some logic in PositionBuilder that updates the position's
castling flags based on the positions of king and rooks.
Supporting changes:
- Add Color:ALL and iterate on that slice
- Add Castle::ALL and iterator on that slice
- Add a CastlingParameters struct that contains BitBoard properties that describe
squares that should be clear of pieces and squares that should not be attacked.
This enables a bunch of clean up! Remove the MoveGenerationParameters and MoveList
types from move_generator::pawn.
Implement BitBoard::pawn_pushes to look up pawn pushes by square and color.
