[core] Implement Slider::ray_direction()

This method returns iterators over the directions each kind of slider can move.

core/src/shapes.rs

@@ -1,10 +1,9 @@
 // Eryn Wells <eryn@erynwells.me>
 
+use crate::{Direction, score::Score};
 use std::{array, fmt, slice, str::FromStr};
 use thiserror::Error;
 
-use crate::score::Score;
-
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 pub enum Shape {
     Pawn = 0,
@@ -93,6 +92,54 @@ pub enum Slider {
     Queen,
 }
 
+impl Slider {
+    pub const NUM: usize = 3;
+    pub const ALL: [Self; Self::NUM] = [Slider::Bishop, Slider::Rook, Slider::Queen];
+
+    /// Return the set of directions a slider can move.
+    ///
+    /// ## Examples
+    ///
+    /// ```
+    /// use chessfriend_core::{Direction, Slider};
+    ///
+    /// assert_eq!(
+    ///     Slider::Bishop.ray_directions().collect::<Vec<Direction>>(),
+    ///     vec![
+    ///         Direction::NorthWest,
+    ///         Direction::NorthEast,
+    ///         Direction::SouthEast,
+    ///         Direction::SouthWest
+    ///     ]
+    /// );
+    /// ```
+    ///
+    #[must_use]
+    pub fn ray_directions(self) -> Box<dyn Iterator<Item = Direction>> {
+        match self {
+            Slider::Bishop => Box::new(
+                [
+                    Direction::NorthWest,
+                    Direction::NorthEast,
+                    Direction::SouthEast,
+                    Direction::SouthWest,
+                ]
+                .into_iter(),
+            ),
+            Slider::Rook => Box::new(
+                [
+                    Direction::North,
+                    Direction::East,
+                    Direction::South,
+                    Direction::West,
+                ]
+                .into_iter(),
+            ),
+            Slider::Queen => Box::new(Direction::ALL.into_iter()),
+        }
+    }
+}
+
 impl From<Slider> for Shape {
     fn from(value: Slider) -> Self {
         match value {