Add 'try_from_index' implementations

src/board/castle_rights.rs

@@ -24,9 +24,18 @@ impl CastleRights {
     /// Panics if the index is out of bounds.
     #[inline(always)]
     pub fn from_index(index: usize) -> Self {
-        assert!(index < Self::NUM_VARIANTS);
-        // SAFETY: we know the value is in-bounds
-        unsafe { Self::from_index_unchecked(index) }
+        Self::try_from_index(index).expect("index out of bouds")
+    }
+
+    /// Convert from a castle rights index into a [CastleRights] type. Returns [None] if the index
+    /// is out of bounds.
+    pub fn try_from_index(index: usize) -> Option<Self> {
+        if index < Self::NUM_VARIANTS {
+            // SAFETY: we know the value is in-bounds
+            Some(unsafe { Self::from_index_unchecked(index) })
+        } else {
+            None
+        }
     }
 
     /// Convert from a castle rights index into a [CastleRights] type, no bounds checking.

src/board/color.rs

@@ -25,9 +25,18 @@ impl Color {
     /// Panics if the index is out of bounds.
     #[inline(always)]
     pub fn from_index(index: usize) -> Self {
-        assert!(index < Self::NUM_VARIANTS);
-        // SAFETY: we know the value is in-bounds
-        unsafe { Self::from_index_unchecked(index) }
+        Self::try_from_index(index).expect("index out of bouds")
+    }
+
+    /// Convert from a color index into a [Color] type. Returns [None] if the index is out of
+    /// bounds.
+    pub fn try_from_index(index: usize) -> Option<Self> {
+        if index < Self::NUM_VARIANTS {
+            // SAFETY: we know the value is in-bounds
+            Some(unsafe { Self::from_index_unchecked(index) })
+        } else {
+            None
+        }
     }
 
     /// Convert from a color index into a [Color] type, no bounds checking.

src/board/file.rs

@@ -41,9 +41,17 @@ impl File {
     /// Panics if the index is out of bounds.
     #[inline(always)]
     pub fn from_index(index: usize) -> Self {
-        assert!(index < Self::NUM_VARIANTS);
-        // SAFETY: we know the value is in-bounds
-        unsafe { Self::from_index_unchecked(index) }
+        Self::try_from_index(index).expect("index out of bouds")
+    }
+
+    /// Convert from a file index into a [File] type. Returns [None] if the index is out of bounds.
+    pub fn try_from_index(index: usize) -> Option<Self> {
+        if index < Self::NUM_VARIANTS {
+            // SAFETY: we know the value is in-bounds
+            Some(unsafe { Self::from_index_unchecked(index) })
+        } else {
+            None
+        }
     }
 
     /// Convert from a file index into a [File] type, no bounds checking.

src/board/piece.rs

@@ -34,9 +34,18 @@ impl Piece {
     /// Panics if the index is out of bounds.
     #[inline(always)]
     pub fn from_index(index: usize) -> Self {
-        assert!(index < Self::NUM_VARIANTS);
-        // SAFETY: we know the value is in-bounds
-        unsafe { Self::from_index_unchecked(index) }
+        Self::try_from_index(index).expect("index out of bouds")
+    }
+
+    /// Convert from a piece index into a [Piece] type. Returns [None] if the index is out of
+    /// bounds.
+    pub fn try_from_index(index: usize) -> Option<Self> {
+        if index < Self::NUM_VARIANTS {
+            // SAFETY: we know the value is in-bounds
+            Some(unsafe { Self::from_index_unchecked(index) })
+        } else {
+            None
+        }
     }
 
     /// Convert from a piece index into a [Piece] type, no bounds checking.

src/board/rank.rs

@@ -41,9 +41,17 @@ impl Rank {
     /// Panics if the index is out of bounds.
     #[inline(always)]
     pub fn from_index(index: usize) -> Self {
-        assert!(index < Self::NUM_VARIANTS);
-        // SAFETY: we know the value is in-bounds
-        unsafe { Self::from_index_unchecked(index) }
+        Self::try_from_index(index).expect("index out of bouds")
+    }
+
+    /// Convert from a rank index into a [Rank] type. Returns [None] if the index is out of bounds.
+    pub fn try_from_index(index: usize) -> Option<Self> {
+        if index < Self::NUM_VARIANTS {
+            // SAFETY: we know the value is in-bounds
+            Some(unsafe { Self::from_index_unchecked(index) })
+        } else {
+            None
+        }
     }
 
     /// Convert from a rank index into a [Rank] type, no bounds checking.

src/board/square.rs

@@ -57,9 +57,18 @@ impl Square {
     /// Convert from a square index into a [Square] type.
     #[inline(always)]
     pub fn from_index(index: usize) -> Self {
-        assert!(index < Self::NUM_VARIANTS);
-        // SAFETY: we know the value is in-bounds
-        unsafe { Self::from_index_unchecked(index) }
+        Self::try_from_index(index).expect("index out of bouds")
+    }
+
+    /// Convert from a square index into a [Square] type. Returns [None] if the index is out of
+    /// bounds.
+    pub fn try_from_index(index: usize) -> Option<Self> {
+        if index < Self::NUM_VARIANTS {
+            // SAFETY: we know the value is in-bounds
+            Some(unsafe { Self::from_index_unchecked(index) })
+        } else {
+            None
+        }
     }
 
     /// Convert from a square index into a [Square] type, no bounds checking.