Added getHandle to slot_map.zig

src/slot_map.zig

@@ -207,6 +207,16 @@ pub fn SlotMap(comptime T: type) type {
             return self.get(handle) != null;
         }
 
+        /// ----------------------------------------------------
+        /// Current valid handle for an index
+        /// Returns null if out of range or the slot is freed
+        /// ----------------------------------------------------
+        pub fn getHandle(self: *const Self, idx: usize) ?Handle(T) {
+            if (idx >= self.values.items.len) return null;
+            if (std.mem.indexOfScalar(u32, self.free_list.items, @intCast(idx)) != null) return null;
+            return .{ .idx = @intCast(idx), .gen = self.generations.items[idx] };
+        }
+
         /// ----------------------------------------------------
         /// Number of live entries
         /// Removed (freed) slots are not counted