possible moves works as expectedgit add .; git commit (now to filter down to actually valid moves...

src/game.rs

@@ -207,43 +207,54 @@ impl Board {
 
     /// Returns the possible moves the piece at this tile can make.
     pub(crate) fn possible_moves(&self, BoardIndex { x, y }: BoardIndex) -> HashSet<BoardIndex> {
+        let f = |(a, b): (Option<usize>, Option<usize>)| {
+            if let (Some(x), Some(y)) = (a, b) {
+                if (0..=7).contains(&x) && (0..=3).contains(&y) {
+                    Some(BoardIndex { x, y })
+                } else {
+                    None
+                }
+            } else {
+                None
+            }
+        };
+
         match self.at(BoardIndex { x, y }) {
             // One space in any diagonal
-            Some(Piece::Pawn) => (-1..=1)
-                .flat_map(move |xi| {
-                    (-1..=1).map(move |yi| BoardIndex {
-                        x: x.checked_add_signed(xi).map_or(0, |val| val).clamp(0, 7),
-                        y: y.checked_add_signed(yi).map_or(0, |val| val).clamp(0, 3),
-                    })
-                })
+            Some(Piece::Pawn) => std::iter::empty()
+                .chain(
+                    (-1..=1)
+                        .zip(-1..=1)
+                        .map(move |(a, b)| (x.checked_add_signed(a), y.checked_add_signed(b))),
+                )
+                .chain(
+                    (-1..=1)
+                        .zip((-1..=1).rev())
+                        .map(move |(a, b)| (x.checked_add_signed(a), y.checked_add_signed(b))),
+                )
+                .filter_map(f)
                 .collect(),
             // One or two spaces in either horizontal
             Some(Piece::Drone) => std::iter::empty()
-                .chain((-2..=2).map(|i| BoardIndex {
-                    x: x.checked_add_signed(i).map_or(0, |val| val).clamp(0, 7),
-                    y,
-                }))
-                .chain((-2..=2).map(|i| BoardIndex {
-                    x,
-                    y: y.checked_add_signed(i).map_or(0, |val| val).clamp(0, 3),
-                }))
+                .chain((-2..=2).map(|i| (x.checked_add_signed(i), Some(y))))
+                .chain((-2..=2).map(|i| (Some(x), y.checked_add_signed(i))))
+                .filter_map(f)
                 .collect(),
             // Any distance in any straight line
             Some(Piece::Queen) => std::iter::empty()
-                .chain((-7..=7).map(|i| BoardIndex {
-                    x: x.checked_add_signed(i).map_or(0, |val| val).clamp(0, 7),
-                    y,
-                }))
-                .chain((-3..=3).map(|i| BoardIndex {
-                    x,
-                    y: y.checked_add_signed(i).map_or(0, |val| val).clamp(0, 3),
-                }))
-                .chain((-3..=3).flat_map(move |xi| {
-                    (-3..=3).map(move |yi| BoardIndex {
-                        x: x.checked_add_signed(xi).map_or(0, |val| val).clamp(0, 7),
-                        y: y.checked_add_signed(yi).map_or(0, |val| val).clamp(0, 3),
-                    })
-                }))
+                .chain((-7..=7).map(|i| (x.checked_add_signed(i), Some(y))))
+                .chain((-3..=3).map(|i| (Some(x), y.checked_add_signed(i))))
+                .chain(
+                    (-3..=3)
+                        .zip(-3..=3)
+                        .map(move |(a, b)| (x.checked_add_signed(a), y.checked_add_signed(b))),
+                )
+                .chain(
+                    (-3..=3)
+                        .zip((-3..=3).rev())
+                        .map(move |(a, b)| (x.checked_add_signed(a), y.checked_add_signed(b))),
+                )
+                .filter_map(f)
                 .collect(),
             None => std::iter::empty().collect(),
         }
@@ -468,9 +479,9 @@ fn asserts<T: Component>(
     if selected_pieces.iter().len() > 2 {
         panic!("More than two piece is selected");
     }
-    if selected_tiles.iter().len() > 1 {
+    if selected_tiles.iter().len() > 2 {
         panic!(
-            "More than one tile is selected {:?}",
+            "More than two tile is selected {:?}",
             selected_tiles.iter().len()
         );
     }