BUG: Fix safety of unchecked elem methods and move them all to the right file

Unchecked indexing is `unsafe`.

Author: bluss

src/arraytraits.rs

@@ -28,26 +28,10 @@ use {Zip, FoldWhile};
 
 #[cold]
 #[inline(never)]
-fn array_out_of_bounds() -> ! {
+pub(crate) fn array_out_of_bounds() -> ! {
     panic!("ndarray: index out of bounds");
 }
 
-// Macro to insert more informative out of bounds message in debug builds
-#[cfg(debug_assertions)]
-macro_rules! debug_bounds_check {
-    ($self_:ident, $index:expr) => {
-        if let None = $index.index_checked(&$self_.dim, &$self_.strides) {
-            panic!("ndarray: index {:?} is out of bounds for array of shape {:?}",
-                   $index, $self_.shape());
-        }
-    };
-}
-
-#[cfg(not(debug_assertions))]
-macro_rules! debug_bounds_check {
-    ($self_:ident, $index:expr) => { };
-}
-
 #[inline(always)]
 pub fn debug_bounds_check<S, D, I>(_a: &ArrayBase<S, D>, _index: &I)
     where D: Dimension,
@@ -94,62 +78,6 @@ impl<S, D, I> IndexMut<I> for ArrayBase<S, D>
     }
 }
 
-impl<'a, A, D> ArrayView<'a, A, D>
-where
-    D: Dimension,
-{
-    /// Get a reference of a element through the view.
-    ///
-    /// 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<I: NdIndex<D>>(&self, index: I) -> &'a A {
-        debug_bounds_check!(self, index);
-        unsafe {
-            &*self.as_ptr().offset(
-                index
-                    .index_checked(&self.dim, &self.strides)
-                    .unwrap_or_else(|| array_out_of_bounds()),
-            )
-        }
-    }
-
-    /// 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,
-{
-    /// 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(
-                index
-                    .index_checked(&self.dim, &self.strides)
-                    .unwrap_or_else(|| array_out_of_bounds()),
-            )
-        }
-    }
-
-    /// 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
 /// `rhs` are equal. Return `false` otherwise.
 impl<S, S2, D> PartialEq<ArrayBase<S2, D>> for ArrayBase<S, D>

src/impl_views.rs

@@ -11,7 +11,8 @@ use std::slice;
 use imp_prelude::*;
 use dimension::{self, stride_offset};
 use error::ShapeError;
-
+use NdIndex;
+use arraytraits::array_out_of_bounds;
 use StrideShape;
 
 use {
@@ -133,6 +134,33 @@ impl<'a, A, D> ArrayView<'a, A, D>
         }
     }
 
+    /// Get a reference of a element through the view.
+    ///
+    /// This method is like `Index::index` but with a longer lifetime (matching
+    /// the array view); which we can't do for general arrays and not in the
+    /// `Index` trait.
+    pub fn elem<I>(&self, index: I) -> &'a A
+        where I: NdIndex<D>,
+    {
+        debug_bounds_check!(self, index);
+        unsafe {
+            &*self.as_ptr().offset(index
+                .index_checked(&self.dim, &self.strides)
+                .unwrap_or_else(|| array_out_of_bounds()))
+        }
+    }
+
+    /// Get a reference of a element through the view without boundary check
+    ///
+    /// This method is like `elem` with a longer lifetime (matching the array
+    /// view); which we can't do for general arrays.
+    pub unsafe fn uelem<I>(&self, index: I) -> &'a A
+        where I: NdIndex<D>,
+    {
+        debug_bounds_check!(self, index);
+        &*self.as_ptr().offset(index.index_unchecked(&self.strides))
+    }
+
 }
 
 /// Methods for read-write array views.
@@ -233,6 +261,33 @@ impl<'a, A, D> ArrayViewMut<'a, A, D>
         self.into_slice_().ok()
     }
 
+    /// Convert a mutable array view to a mutable reference of a element.
+    ///
+    /// This method is like `Index::index` but with a longer lifetime (matching
+    /// the array view); which we can't do for general arrays and not in the
+    /// `Index` trait.
+    pub fn into_elem<I>(mut self, index: I) -> &'a mut A
+        where I: NdIndex<D>,
+    {
+        debug_bounds_check!(self, index);
+        unsafe {
+            &mut *self.as_mut_ptr().offset(
+                index
+                    .index_checked(&self.dim, &self.strides)
+                    .unwrap_or_else(|| array_out_of_bounds()),
+            )
+        }
+    }
+
+    /// Convert a mutable array view to a mutable reference of a element without boundary check
+    ///
+    ///
+    pub unsafe fn into_elem_unchecked<I>(mut self, index: I) -> &'a mut A
+        where I: NdIndex<D>
+    {
+        debug_bounds_check!(self, index);
+        &mut *self.as_mut_ptr().offset(index.index_unchecked(&self.strides))
+    }
 }
 
 /// Private array view methods

src/macro_utils.rs

@@ -55,3 +55,20 @@ macro_rules! expand_if {
     };
     (@nonempty [] $($body:tt)*) => { };
 }
+
+// Macro to insert more informative out of bounds message in debug builds
+#[cfg(debug_assertions)]
+macro_rules! debug_bounds_check {
+    ($self_:ident, $index:expr) => {
+        if let None = $index.index_checked(&$self_.dim, &$self_.strides) {
+            panic!("ndarray: index {:?} is out of bounds for array of shape {:?}",
+                   $index, $self_.shape());
+        }
+    };
+}
+
+#[cfg(not(debug_assertions))]
+macro_rules! debug_bounds_check {
+    ($self_:ident, $index:expr) => { };
+}
+