Implement a whole new move crate

moves/src/builder.rs

@@ -1,9 +1,35 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use crate::{castle, Move};
-use chessfriend_core::{PlacedPiece, Square};
+use crate::{castle, defs::Kind, Move, PromotionShape};
+use chessfriend_core::{Color, File, PlacedPiece, Rank, Square};
+use std::result::Result as StdResult;
 
-pub trait Style {}
+pub type Result = std::result::Result<Move, Error>;
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum Error {
+    MissingOriginSquare,
+    MissingTargetSquare,
+    MissingCaptureSquare,
+    InvalidEnPassantSquare,
+}
+
+pub trait Style {
+    fn origin_square(&self) -> Option<Square> {
+        None
+    }
+
+    fn target_square(&self) -> Option<Square> {
+        None
+    }
+
+    fn into_move_bits(&self) -> StdResult<u16, Error> {
+        let origin_square = self.origin_square().ok_or(Error::MissingOriginSquare)? as u16;
+        let target_square = self.target_square().ok_or(Error::MissingTargetSquare)? as u16;
+
+        Ok((origin_square & 0b111111) << 4 | (target_square & 0b111111) << 10)
+    }
+}
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct Builder<S: Style> {
@@ -19,67 +45,241 @@ pub struct Push {
     to: Option<Square>,
 }
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct DoublePush {
+    from: Square,
+    to: Square,
+}
+
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct Capture {
     push: Push,
     capture: Option<Square>,
 }
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct EnPassantCapture {
+    push: Push,
+    capture: Option<Square>,
+}
+
+pub struct Promotion<S> {
+    style: S,
+    promotion: PromotionShape,
+}
+
 pub struct Castle {
     castle: castle::Castle,
 }
 
 impl Style for Null {}
-impl Style for Push {}
-impl Style for Capture {}
+
+impl Style for Push {
+    fn origin_square(&self) -> Option<Square> {
+        self.from
+    }
+
+    fn target_square(&self) -> Option<Square> {
+        self.to
+    }
+}
+
+impl Style for Capture {
+    fn origin_square(&self) -> Option<Square> {
+        self.push.from
+    }
+
+    fn target_square(&self) -> Option<Square> {
+        self.push.to
+    }
+}
+
 impl Style for Castle {}
 
+impl Style for DoublePush {
+    fn origin_square(&self) -> Option<Square> {
+        Some(self.from)
+    }
+
+    fn target_square(&self) -> Option<Square> {
+        Some(self.to)
+    }
+
+    fn into_move_bits(&self) -> StdResult<u16, Error> {
+        Ok(Kind::DoublePush as u16
+            | (self.from as u16 & 0b111111) << 4
+            | (self.to as u16 & 0b111111) << 10)
+    }
+}
+
+impl Style for EnPassantCapture {
+    fn origin_square(&self) -> Option<Square> {
+        self.push.from
+    }
+
+    fn target_square(&self) -> Option<Square> {
+        self.push.to
+    }
+
+    fn into_move_bits(&self) -> StdResult<u16, Error> {
+        let origin_square = self.origin_square().ok_or(Error::MissingOriginSquare)? as u16;
+        let target_square = self.target_square().ok_or(Error::MissingTargetSquare)? as u16;
+
+        Ok((origin_square & 0b111111) << 4 | (target_square & 0b111111) << 10)
+    }
+}
+
+impl Style for Promotion<Push> {
+    fn origin_square(&self) -> Option<Square> {
+        self.style.from
+    }
+
+    fn target_square(&self) -> Option<Square> {
+        self.style.to
+    }
+}
+
+impl Style for Promotion<Capture> {
+    fn origin_square(&self) -> Option<Square> {
+        self.style.push.from
+    }
+
+    fn target_square(&self) -> Option<Square> {
+        self.style.push.to
+    }
+}
+
+impl Promotion<Push> {
+    fn into_move_bits(&self) -> StdResult<u16, Error> {
+        let origin_square = self
+            .style
+            .origin_square()
+            .ok_or(Error::MissingOriginSquare)? as u16;
+        let target_square = self
+            .style
+            .target_square()
+            .ok_or(Error::MissingTargetSquare)? as u16;
+
+        Ok(Kind::Promotion as u16
+            | self.promotion as u16
+            | (origin_square & 0b111111) << 4
+            | (target_square & 0b111111) << 10)
+    }
+}
+
+impl Promotion<Capture> {
+    fn into_move_bits(&self) -> StdResult<u16, Error> {
+        let origin_square = self
+            .style
+            .origin_square()
+            .ok_or(Error::MissingOriginSquare)? as u16;
+        let target_square = self
+            .style
+            .target_square()
+            .ok_or(Error::MissingTargetSquare)? as u16;
+
+        Ok(Kind::CapturePromotion as u16
+            | self.promotion as u16
+            | (origin_square & 0b111111) << 4
+            | (target_square & 0b111111) << 10)
+    }
+}
+
 impl Builder<Null> {
     pub fn new() -> Self {
         Self { style: Null }
     }
 
-    pub fn piece(piece: &PlacedPiece) -> Builder<Push> {
+    pub fn push(piece: &PlacedPiece, to: Square) -> Builder<Push> {
         Builder {
             style: Push {
                 from: Some(piece.square()),
-                to: None,
+                to: Some(to),
             },
         }
     }
 
+    pub fn double_push(file: File, color: Color) -> Builder<DoublePush> {
+        let (from, to) = match color {
+            Color::White => (
+                Square::from_file_rank(file, Rank::TWO),
+                Square::from_file_rank(file, Rank::FOUR),
+            ),
+            Color::Black => (
+                Square::from_file_rank(file, Rank::SEVEN),
+                Square::from_file_rank(file, Rank::FIVE),
+            ),
+        };
+
+        Builder {
+            style: DoublePush { from, to },
+        }
+    }
+
     pub fn castling(castle: castle::Castle) -> Builder<Castle> {
         Builder {
             style: Castle { castle },
         }
     }
 
+    pub fn capturing_on(piece: &PlacedPiece, to: Square) -> Builder<Capture> {
+        Self::push(piece, to).capturing_on(to)
+    }
+
+    pub fn capturing_piece(piece: &PlacedPiece, capturing: &PlacedPiece) -> Builder<Capture> {
+        Self::push(piece, capturing.square()).capturing_piece(&capturing)
+    }
+
+    pub fn from(self, square: Square) -> Builder<Push> {
+        Builder {
+            style: Push {
+                from: Some(square),
+                to: None,
+            },
+        }
+    }
+
     pub fn build(&self) -> Move {
         Move(0)
     }
 }
 
 impl Builder<Push> {
-    pub fn from(mut self, square: Square) -> Self {
+    pub fn from(&mut self, square: Square) -> &mut Self {
         self.style.from = Some(square);
         self
     }
 
-    pub fn to(mut self, square: Square) -> Self {
+    pub fn to(&mut self, square: Square) -> &mut Self {
         self.style.to = Some(square);
         self
     }
 
-    pub fn capturing(self, square: Square) -> Builder<Capture> {
+    pub fn capturing_on(self, square: Square) -> Builder<Capture> {
+        let mut style = self.style;
+        style.to = Some(square);
+
         Builder {
             style: Capture {
+                push: style,
+                capture: Some(square),
+            },
+        }
+    }
+
+    pub fn capturing_en_passant_on(self, square: Square) -> Builder<EnPassantCapture> {
+        let mut style = self.style;
+        style.to = Some(square);
+
+        Builder {
+            style: EnPassantCapture {
                 push: self.style,
                 capture: Some(square),
             },
         }
     }
 
-    pub fn capturing_piece(self, piece: PlacedPiece) -> Builder<Capture> {
+    pub fn capturing_piece(self, piece: &PlacedPiece) -> Builder<Capture> {
         Builder {
             style: Capture {
                 push: self.style,
@@ -87,19 +287,73 @@ impl Builder<Push> {
             },
         }
     }
+
+    pub fn promoting_to(self, shape: PromotionShape) -> Builder<Promotion<Push>> {
+        Builder {
+            style: Promotion {
+                style: self.style,
+                promotion: shape,
+            },
+        }
+    }
+
+    pub fn build(&self) -> Result {
+        Ok(Move(Kind::Quiet as u16 | self.style.into_move_bits()?))
+    }
 }
 
 impl Builder<Castle> {
+    fn bits(&self) -> u16 {
+        let bits = match self.style.castle {
+            castle::Castle::KingSide => Kind::KingSideCastle,
+            castle::Castle::QueenSide => Kind::QueenSideCastle,
+        };
+
+        bits as u16
+    }
+
     pub fn build(&self) -> Move {
-        Move(self.style.into_bits())
+        Move(self.bits())
     }
 }
 
-impl Castle {
-    fn into_bits(&self) -> u16 {
-        match self.castle {
-            castle::Castle::KingSide => 0b10,
-            castle::Castle::QueenSide => 0b11,
+impl Builder<Capture> {
+    pub fn promoting_to(self, shape: PromotionShape) -> Builder<Promotion<Capture>> {
+        Builder {
+            style: Promotion {
+                style: self.style,
+                promotion: shape,
+            },
         }
     }
+
+    pub fn build(&self) -> Result {
+        Ok(Move(Kind::Capture as u16 | self.style.into_move_bits()?))
+    }
+}
+
+impl Builder<DoublePush> {
+    pub fn build(&self) -> Result {
+        Ok(Move(Kind::DoublePush as u16 | self.style.into_move_bits()?))
+    }
+}
+
+impl Builder<EnPassantCapture> {
+    pub unsafe fn build_unchecked(&self) -> Result {
+        Ok(Move(
+            Kind::EnPassantCapture as u16 | self.style.into_move_bits()?,
+        ))
+    }
+}
+
+impl Builder<Promotion<Push>> {
+    pub fn build(&self) -> Result {
+        Ok(Move(self.style.into_move_bits()?))
+    }
+}
+
+impl Builder<Promotion<Capture>> {
+    pub fn build(&self) -> Result {
+        Ok(Move(self.style.into_move_bits()?))
+    }
 }

moves/src/castle.rs

@@ -1,17 +1,26 @@
 // Eryn Wells <eryn@erynwells.me>
 
 use chessfriend_bitboard::BitBoard;
-use chessfriend_core::{Color, Square};
+use chessfriend_core::Square;
 
-#[repr(u16)]
+#[repr(u8)]
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum Castle {
-    KingSide = 0b10,
-    QueenSide = 0b11,
+    KingSide = 0,
+    QueenSide = 1,
 }
 
 pub(crate) struct CastlingParameters {
+    /// Origin squares of the king and rook.
+    origin_squares: Squares,
+
+    /// Target or destination squares for the king and rook.
+    target_squares: Squares,
+
+    /// The set of squares that must be clear of any pieces in order to perform this castle.
     clear_squares: BitBoard,
+
+    /// The set of squares that must not be attacked in order to perform this castle.
     check_squares: BitBoard,
 }
 
@@ -24,87 +33,59 @@ pub(crate) struct Squares {
 impl Castle {
     pub const ALL: [Castle; 2] = [Castle::KingSide, Castle::QueenSide];
 
-    const STARTING_SQUARES: [[Squares; 2]; 2] = [
+    /// Parameters for each castling move, organized by color and board-side.
+    const PARAMETERS: [[CastlingParameters; 2]; 2] = [
         [
-            Squares {
-                king: Square::E1,
-                rook: Square::H1,
-            },
-            Squares {
-                king: Square::E1,
-                rook: Square::A1,
-            },
-        ],
-        [
-            Squares {
-                king: Square::E8,
-                rook: Square::H8,
-            },
-            Squares {
-                king: Square::E8,
-                rook: Square::A8,
-            },
-        ],
-    ];
-
-    const TARGET_SQUARES: [[Squares; 2]; 2] = [
-        [
-            Squares {
-                king: Square::G1,
-                rook: Square::F1,
-            },
-            Squares {
-                king: Square::C1,
-                rook: Square::D1,
-            },
-        ],
-        [
-            Squares {
-                king: Square::G8,
-                rook: Square::F8,
-            },
-            Squares {
-                king: Square::C8,
-                rook: Square::D8,
-            },
-        ],
-    ];
-
-    pub(crate) fn starting_squares(&self, color: Color) -> &'static Squares {
-        &Castle::STARTING_SQUARES[color as usize][self.into_index()]
-    }
-
-    pub(crate) fn target_squares(&self, color: Color) -> &'static Squares {
-        &Castle::TARGET_SQUARES[color as usize][self.into_index()]
-    }
-
-    pub(crate) fn into_index(&self) -> usize {
-        match self {
-            Castle::KingSide => 0,
-            Castle::QueenSide => 1,
-        }
-    }
-
-    pub(crate) fn parameters(&self) -> CastlingParameters {
-        match self {
-            Castle::KingSide => CastlingParameters {
+            CastlingParameters {
+                origin_squares: Squares {
+                    king: Square::E1,
+                    rook: Square::H1,
+                },
+                target_squares: Squares {
+                    king: Square::G1,
+                    rook: Square::F1,
+                },
                 clear_squares: BitBoard::new(0b01100000),
                 check_squares: BitBoard::new(0b01110000),
             },
-            Castle::QueenSide => CastlingParameters {
+            CastlingParameters {
+                origin_squares: Squares {
+                    king: Square::E1,
+                    rook: Square::A1,
+                },
+                target_squares: Squares {
+                    king: Square::C1,
+                    rook: Square::D1,
+                },
                 clear_squares: BitBoard::new(0b00001110),
                 check_squares: BitBoard::new(0b00011100),
             },
-        }
-    }
-}
-
-impl CastlingParameters {
-    pub fn clear_squares(&self) -> &BitBoard {
-        &self.clear_squares
-    }
-
-    pub fn check_squares(&self) -> &BitBoard {
-        &self.check_squares
-    }
+        ],
+        [
+            CastlingParameters {
+                origin_squares: Squares {
+                    king: Square::E8,
+                    rook: Square::H8,
+                },
+                target_squares: Squares {
+                    king: Square::G8,
+                    rook: Square::F8,
+                },
+                clear_squares: BitBoard::new(0b01100000 << 8 * 7),
+                check_squares: BitBoard::new(0b01110000 << 8 * 7),
+            },
+            CastlingParameters {
+                origin_squares: Squares {
+                    king: Square::E8,
+                    rook: Square::A8,
+                },
+                target_squares: Squares {
+                    king: Square::C8,
+                    rook: Square::D8,
+                },
+                clear_squares: BitBoard::new(0b00001110 << 8 * 7),
+                check_squares: BitBoard::new(0b00011100 << 8 * 7),
+            },
+        ],
+    ];
 }

moves/src/defs.rs

@@ -0,0 +1,34 @@
+// Eryn Wells <eryn@erynwells.me>
+
+use chessfriend_core::Shape;
+
+pub(crate) enum Kind {
+    Quiet = 0b00,
+    DoublePush = 0b01,
+    KingSideCastle = 0b10,
+    QueenSideCastle = 0b11,
+    Capture = 0b0100,
+    EnPassantCapture = 0b0101,
+    Promotion = 0b1000,
+    CapturePromotion = 0b1100,
+}
+
+#[repr(u16)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum PromotionShape {
+    Knight = 0b00,
+    Bishop = 0b01,
+    Rook = 0b10,
+    Queen = 0b11,
+}
+
+impl From<PromotionShape> for Shape {
+    fn from(value: PromotionShape) -> Self {
+        match value {
+            PromotionShape::Knight => Shape::Knight,
+            PromotionShape::Bishop => Shape::Bishop,
+            PromotionShape::Rook => Shape::Rook,
+            PromotionShape::Queen => Shape::Queen,
+        }
+    }
+}

moves/src/lib.rs

@@ -2,7 +2,10 @@
 
 mod builder;
 mod castle;
+mod defs;
 mod moves;
 
-pub use builder::Builder;
+pub use builder::{Builder, Error as BuilderError};
+pub use castle::Castle;
+pub use defs::PromotionShape;
 pub use moves::Move;

moves/src/moves.rs

@@ -1,72 +1,45 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use crate::castle::Castle;
-use chessfriend_core::{PlacedPiece, Shape, Square};
+use crate::{castle::Castle, defs::Kind};
+use chessfriend_core::{Rank, Shape, Square};
 use std::fmt;
 
-#[repr(u16)]
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
-pub enum PromotableShape {
-    Knight = 0b00,
-    Bishop = 0b01,
-    Rook = 0b10,
-    Queen = 0b11,
-}
-
-#[repr(u16)]
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
-enum Kind {
-    Quiet = 0b00,
-    DoublePush = 0b01,
-    Castle(Castle),
-    Capture(PlacedPiece) = 0b0100,
-    EnPassantCapture(PlacedPiece) = 0b0101,
-    Promotion(PromotableShape) = 0b1000,
-    CapturePromotion(PlacedPiece, PromotableShape) = 0b1100,
-}
-
-impl Kind {
-    fn bits(&self) -> u16 {
-        match self {
-            Self::Promotion(shape) => self.discriminant() | *shape as u16,
-            Self::CapturePromotion(_, shape) => self.discriminant() | *shape as u16,
-            Self::Castle(castle) => *castle as u16,
-            _ => self.discriminant(),
-        }
-    }
-
-    /// Return the discriminant value. This implementation is copied from the Rust docs.
-    /// See https://doc.rust-lang.org/std/mem/fn.discriminant.html
-    fn discriminant(&self) -> u16 {
-        unsafe { *<*const _>::from(self).cast::<u16>() }
-    }
-}
-
-impl Default for Kind {
-    fn default() -> Self {
-        Self::Quiet
-    }
-}
-
 /// A single player's move. In chess parlance, this is a "ply".
 #[derive(Clone, Copy, Eq, Hash, PartialEq)]
 pub struct Move(pub(crate) u16);
 
 impl Move {
-    pub fn from_square(&self) -> Square {
+    pub fn origin_square(&self) -> Square {
         ((self.0 >> 4) & 0b111111).try_into().unwrap()
     }
 
-    pub fn to_square(&self) -> Square {
+    pub fn target_square(&self) -> Square {
         (self.0 >> 10).try_into().unwrap()
     }
 
+    pub fn capture_square(&self) -> Option<Square> {
+        if self.is_capture() {
+            return Some(self.target_square());
+        }
+
+        if self.is_en_passant() {
+            let target_square = self.target_square();
+            return Some(match target_square.rank() {
+                Rank::THREE => Square::from_file_rank(target_square.file(), Rank::FOUR),
+                Rank::SIX => Square::from_file_rank(target_square.file(), Rank::FIVE),
+                _ => unreachable!(),
+            });
+        }
+
+        None
+    }
+
     pub fn is_quiet(&self) -> bool {
-        self.flags() == Kind::Quiet.discriminant()
+        self.flags() == Kind::Quiet as u16
     }
 
     pub fn is_double_push(&self) -> bool {
-        self.flags() == Kind::DoublePush.discriminant()
+        self.flags() == Kind::DoublePush as u16
     }
 
     pub fn is_castle(&self) -> bool {

moves/tests/flags.rs

@@ -0,0 +1,104 @@
+// Eryn Wells <eryn@erynwells.me>
+
+use chessfriend_core::{piece, Color, File, Shape, Square};
+use chessfriend_moves::{Builder, BuilderError, Castle, PromotionShape};
+
+macro_rules! assert_flag {
+    ($move:expr, $left:expr, $right:expr, $desc:expr) => {
+        assert_eq!($left, $right, "{:?} -> {}", $move, stringify!($desc))
+    };
+}
+
+macro_rules! assert_flags {
+    ($move:expr, $quiet:expr, $double_push:expr, $en_passant:expr, $capture:expr, $castle:expr, $promotion:expr) => {
+        assert_flag!($move, $move.is_quiet(), $quiet, "is_quiet");
+        assert_flag!(
+            $move,
+            $move.is_double_push(),
+            $double_push,
+            "is_double_push"
+        );
+        assert_flag!($move, $move.is_en_passant(), $en_passant, "is_en_passant");
+        assert_flag!($move, $move.is_capture(), $capture, "is_capture");
+        assert_flag!($move, $move.is_castle(), $castle, "is_castle");
+        assert_flag!($move, $move.is_promotion(), $promotion, "is_promotion");
+    };
+}
+
+#[test]
+fn move_flags_quiet() -> Result<(), BuilderError> {
+    let mv = Builder::push(&piece!(White Pawn on A4), Square::A5).build()?;
+    assert_flags!(mv, true, false, false, false, false, false);
+
+    Ok(())
+}
+
+#[test]
+fn move_flags_double_push() -> Result<(), BuilderError> {
+    let mv = Builder::double_push(File::C, Color::White).build()?;
+    assert_flags!(mv, false, true, false, false, false, false);
+
+    Ok(())
+}
+
+#[test]
+fn move_flags_capture() -> Result<(), BuilderError> {
+    let mv = Builder::new()
+        .from(Square::A4)
+        .capturing_on(Square::B5)
+        .build()?;
+
+    assert_flags!(mv, false, false, false, true, false, false);
+
+    Ok(())
+}
+
+#[test]
+fn move_flags_en_passant_capture() -> Result<(), BuilderError> {
+    let mv = unsafe {
+        Builder::new()
+            .from(Square::A5)
+            .capturing_en_passant_on(Square::B4)
+            .build_unchecked()?
+    };
+
+    assert_flags!(mv, false, false, true, true, false, false);
+    assert_eq!(mv.origin_square(), Square::A5);
+    assert_eq!(mv.target_square(), Square::B4);
+
+    Ok(())
+}
+
+#[test]
+fn move_flags_promotion() -> Result<(), BuilderError> {
+    let mv = Builder::push(&piece!(White Pawn on H7), Square::H8)
+        .promoting_to(PromotionShape::Queen)
+        .build()?;
+
+    assert_flags!(mv, false, false, false, false, false, true);
+    assert_eq!(mv.promotion(), Some(Shape::Queen));
+
+    Ok(())
+}
+
+#[test]
+fn move_flags_capture_promotion() -> Result<(), BuilderError> {
+    let mv = Builder::push(&piece!(White Pawn on H7), Square::H8)
+        .capturing_piece(&piece!(Black Knight on G8))
+        .promoting_to(PromotionShape::Queen)
+        .build()?;
+
+    assert_flags!(mv, false, false, false, true, false, true);
+    assert_eq!(mv.promotion(), Some(Shape::Queen));
+
+    Ok(())
+}
+
+#[test]
+fn move_flags_castle() -> Result<(), BuilderError> {
+    let mv = Builder::castling(Castle::KingSide).build();
+
+    assert_flags!(mv, false, false, false, false, true, false);
+
+    Ok(())
+}

moves/tests/pushes.rs

@@ -0,0 +1,15 @@
+// Eryn Wells <eryn@erynwells.me>
+
+use chessfriend_core::{piece, Square};
+use chessfriend_moves::{Builder, BuilderError};
+
+#[test]
+fn pawn_push() -> Result<(), BuilderError> {
+    let mv = Builder::push(&piece!(White Pawn on A3), Square::A4).build()?;
+
+    assert!(mv.is_quiet());
+    assert_eq!(mv.origin_square(), Square::A3);
+    assert_eq!(mv.target_square(), Square::A4);
+
+    Ok(())
+}