is_unique for arcarray

src/impl_arc_array.rs

@@ -6,8 +6,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use alloc::sync::Arc;
 use crate::imp_prelude::*;
+use alloc::sync::Arc;
 
 /// Methods specific to `ArcArray`.
 ///
@@ -17,7 +17,9 @@ where
     D: Dimension,
 {
     /// Returns `true` iff the inner `Arc` is not shared.
-    pub fn is_unique(&mut self) -> bool {
-        Arc::get_mut(&mut self.data.0).is_some()
+    /// If you want to ensure the Arc is not concurrently cloned, you need to provide a `&mut self` to this function.
+    pub fn is_unique(&self) -> bool {
+        // Only strong pointers are used in this crate.
+        Arc::strong_count(&self.data.0) == 1
     }
 }