Sync scores between players

board-shared/src/score.rs

@@ -0,0 +1,79 @@
+use crate::tile::{Operator, Tile};
+
+/// Calculate the score for a given list of tiles.
+pub fn calc_score(tiles: &[Tile]) -> u32 {
+    tiles
+        .split(|tile| matches!(tile, Tile::Equals))
+        .map(calc_expression_score)
+        .sum()
+}
+
+fn calc_expression_score(tiles: &[Tile]) -> u32 {
+    let mut digit_score = 0u32;
+    let mut multiplier = 1u32;
+    for token in tiles {
+        match token {
+            Tile::Digit(_) => digit_score += 1,
+            Tile::Operator(op) => {
+                match op {
+                    Operator::Add | Operator::Subtract => multiplier = 2,
+                    Operator::Multiply => multiplier = 3,
+                    Operator::Divide => digit_score += 10,
+                };
+            }
+            _ => unreachable!(),
+        }
+    }
+    digit_score * multiplier
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tile::Digit;
+
+    use super::*;
+
+    #[test]
+    fn only_digits() {
+        assert_eq!(
+            calc_score(&[
+                Tile::Digit(Digit::new(7)),
+                Tile::Digit(Digit::new(8)),
+                Tile::Equals,
+                Tile::Digit(Digit::new(9)),
+                Tile::Digit(Digit::new(4)),
+            ]),
+            4
+        );
+    }
+
+    #[test]
+    fn calc_individually() {
+        assert_eq!(
+            calc_score(&[
+                Tile::Digit(Digit::new(4)),
+                Tile::Operator(Operator::Add),
+                Tile::Digit(Digit::new(5)),
+                Tile::Equals,
+                Tile::Digit(Digit::new(3)),
+                Tile::Operator(Operator::Multiply),
+                Tile::Digit(Digit::new(3)),
+            ]),
+            10
+        );
+    }
+
+    #[test]
+    fn diviser_add_to_original_sum() {
+        assert_eq!(
+            calc_score(&[
+                Tile::Digit(Digit::new(8)),
+                Tile::Operator(Operator::Divide),
+                Tile::Digit(Digit::new(4)),
+                Tile::Equals,
+                Tile::Digit(Digit::new(2)),
+            ]),
+            13
+        );
+    }
+}