Implement a whole new move crate

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 {