[board] Clean up interfaces of pieces and square structs

board/src/square.rs

@@ -21,28 +21,12 @@ pub struct SquareOutOfBoundsError;
 
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 pub struct Square {
-    pub rank: u8,
-    pub file: u8,
-    pub index: u8,
+    rank: u8,
+    file: u8,
+    index: u8,
 }
 
 impl Square {
-    pub fn from_index(index: u8) -> Result<Square, SquareOutOfBoundsError> {
-        if index >= 64 {
-            return Err(SquareOutOfBoundsError);
-        }
-
-        Ok(Square::from_index_unsafe(index))
-    }
-
-    pub(crate) fn from_index_unsafe(index: u8) -> Square {
-        Square {
-            rank: index / 8,
-            file: index % 8,
-            index: index,
-        }
-    }
-
     pub fn from_rank_file(rank: u8, file: u8) -> Result<Square, SquareOutOfBoundsError> {
         if rank >= 8 || file >= 8 {
             return Err(SquareOutOfBoundsError);
@@ -59,6 +43,10 @@ impl Square {
         s.parse()
     }
 
+    pub fn rank_file(&self) -> (u8, u8) {
+        (self.rank, self.file)
+    }
+
     pub fn neighbor(&self, direction: Direction) -> Option<Square> {
         match direction {
             Direction::North => Square::from_index(self.index + 8),
@@ -110,6 +98,28 @@ impl Square {
     }
 }
 
+impl Square {
+    pub(crate) fn from_index(index: u8) -> Result<Square, SquareOutOfBoundsError> {
+        if index >= 64 {
+            return Err(SquareOutOfBoundsError);
+        }
+
+        Ok(Square::from_index_unsafe(index))
+    }
+
+    pub(crate) fn from_index_unsafe(index: u8) -> Square {
+        Square {
+            rank: index / 8,
+            file: index % 8,
+            index: index,
+        }
+    }
+
+    pub(crate) fn index(&self) -> u8 {
+        self.index
+    }
+}
+
 impl FromStr for Square {
     type Err = ParseSquareError;