Rename to elem/into_elem and add unchecked versions

Author: termoshtt

src/arraytraits.rs

@@ -103,7 +103,7 @@ where
     ///
     /// This is a replacement of `Index::index` since it forces us a wrong lifetime
     /// https://github.com/bluss/rust-ndarray/issues/371
-    pub fn elem_ref<I: NdIndex<D>>(&self, index: I) -> &'a A {
+    pub fn elem<I: NdIndex<D>>(&self, index: I) -> &'a A {
         debug_bounds_check!(self, index);
         unsafe {
             &*self.as_ptr().offset(
@@ -113,17 +113,23 @@ where
             )
         }
     }
+
+    /// Get a reference of a element through the view without boundary check
+    ///
+    /// This is a replacement of `Index::index` since it forces us a wrong lifetime
+    /// https://github.com/bluss/rust-ndarray/issues/371
+    pub fn uelem<I: NdIndex<D>>(&self, index: I) -> &'a A {
+        debug_bounds_check!(self, index);
+        unsafe { &*self.as_ptr().offset(index.index_unchecked(&self.strides)) }
+    }
 }
 
 impl<'a, A, D> ArrayViewMut<'a, A, D>
 where
     D: Dimension,
 {
-    /// Get a mutable reference of a element through the view.
-    ///
-    /// This is a replacement of `IndexMut::index_mut` since it forces us a wrong lifetime
-    /// https://github.com/bluss/rust-ndarray/issues/371
-    pub fn elem_ref_mut<I: NdIndex<D>>(&mut self, index: I) -> &'a mut A {
+    /// Convert a mutable array view to a mutable reference of a element.
+    pub fn into_elem<I: NdIndex<D>>(mut self, index: I) -> &'a mut A {
         debug_bounds_check!(self, index);
         unsafe {
             &mut *self.as_mut_ptr().offset(
@@ -133,6 +139,16 @@ where
             )
         }
     }
+
+    /// Convert a mutable array view to a mutable reference of a element without boundary check
+    pub fn into_elem_unchecked<I: NdIndex<D>>(mut self, index: I) -> &'a mut A {
+        debug_bounds_check!(self, index);
+        unsafe {
+            &mut *self.as_mut_ptr().offset(
+                index.index_unchecked(&self.strides),
+            )
+        }
+    }
 }
 
 /// Return `true` if the array shapes and all elements of `self` and