Implement making double push and promotion moves. Then write several tests to
exercise these. Add convenient static functions to the Move struct to build moves
quickly, without using the Builder.
Add a is_promotable_rank() method to Rank to check that a rank can be used for
promotion moves.
The tests found and fixed a bug in pawn movement where the en passant square was
being discarded when deciding whether an e.p. move can be made.
Implement a new method on Position that evaluates whether the active color can castle
on a given wing of the board. Then, implement making a castling move in the position.
Make a new Wing enum in the core crate to specify kingside or queenside. Replace the
Castle enum from the board crate with this one. This caused a lot of churn...
Along the way fix a bunch of tests.
Note: there's still no way to actually make a castling move in explorer.
Implement thiserror::Error for a bunch of error types, and remove string errors
from the implementation of the command handler in explorer.
Clean up parsing of basic types all over the place.
Update Cargo files to include thiserror and anyhow.
- Add chessfriend_core::Color::NUM
- All the library getters can be const.
- Use the constants from the core library to define the length of the slices in
the Library struct.
- Order the values of Direction in a clockwise fashion
- Implement Direction::opposite() to return the opposing direction
- Make some small changes to the macros in this file to improve readability, maybe.
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.
