Don’t make the ColumnIter[Mut] fields pub(crate)

src/base/iter.rs

@@ -300,8 +300,8 @@ impl<'a, T: Scalar, R: Dim, C: Dim, S: 'a + RawStorageMut<T, R, C>> ExactSizeIte
 #[derive(Clone, Debug)]
 /// An iterator through the columns of a matrix.
 pub struct ColumnIter<'a, T, R: Dim, C: Dim, S: RawStorage<T, R, C>> {
-    pub(crate) mat: &'a Matrix<T, R, C, S>,
+    mat: &'a Matrix<T, R, C, S>,
-    pub(crate) range: Range<usize>,
+    range: Range<usize>,
 }
 
 impl<'a, T, R: Dim, C: Dim, S: 'a + RawStorage<T, R, C>> ColumnIter<'a, T, R, C, S> {
@@ -312,6 +312,22 @@ impl<'a, T, R: Dim, C: Dim, S: 'a + RawStorage<T, R, C>> ColumnIter<'a, T, R, C,
             range: 0..mat.ncols(),
         }
     }
+
+    pub(crate) fn split_at(self, index: usize) -> (Self, Self) {
+        // SAFETY: it’s OK even if index > self.range.len() because
+        //         the iterations will yield None in this case.
+        let left_iter = ColumnIter {
+            mat: self.mat,
+            range: self.range.start..(self.range.start + index),
+        };
+
+        let right_iter = ColumnIter {
+            mat: self.mat,
+            range: (self.range.start + index)..self.range.end,
+        };
+
+        (left_iter, right_iter)
+    }
 }
 
 impl<'a, T, R: Dim, C: Dim, S: 'a + RawStorage<T, R, C>> Iterator for ColumnIter<'a, T, R, C, S> {
@@ -369,9 +385,9 @@ impl<'a, T: Scalar, R: Dim, C: Dim, S: 'a + RawStorage<T, R, C>> ExactSizeIterat
 /// An iterator through the mutable columns of a matrix.
 #[derive(Debug)]
 pub struct ColumnIterMut<'a, T, R: Dim, C: Dim, S: RawStorageMut<T, R, C>> {
-    pub(crate) mat: *mut Matrix<T, R, C, S>,
+    mat: *mut Matrix<T, R, C, S>,
-    pub(crate) range: Range<usize>,
+    range: Range<usize>,
-    pub(crate) phantom: PhantomData<&'a mut Matrix<T, R, C, S>>,
+    phantom: PhantomData<&'a mut Matrix<T, R, C, S>>,
 }
 
 impl<'a, T, R: Dim, C: Dim, S: 'a + RawStorageMut<T, R, C>> ColumnIterMut<'a, T, R, C, S> {
@@ -384,6 +400,26 @@ impl<'a, T, R: Dim, C: Dim, S: 'a + RawStorageMut<T, R, C>> ColumnIterMut<'a, T,
         }
     }
 
+    pub(crate) fn split_at(self, index: usize) -> (Self, Self) {
+        // SAFETY: it’s OK even if index > self.range.len() because
+        //         the iterations will yield None in this case.
+        assert!(index <= self.range.len());
+
+        let left_iter = ColumnIterMut {
+            mat: self.mat,
+            range: self.range.start..(self.range.start + index),
+            phantom: Default::default(),
+        };
+
+        let right_iter = ColumnIterMut {
+            mat: self.mat,
+            range: (self.range.start + index)..self.range.end,
+            phantom: Default::default(),
+        };
+
+        (left_iter, right_iter)
+    }
+
     fn ncols(&self) -> usize {
         unsafe { (*self.mat).ncols() }
     }

src/base/par_iter.rs

@@ -14,7 +14,7 @@ use rayon::{iter::plumbing::bridge, prelude::*};
 /// A rayon parallel iterator over the colums of a matrix. It is created
 /// using the [`par_column_iter`] method of [`Matrix`].
 ///
-/// *only availabe if compiled with the feature `par-iter`*
+/// *Only available if compiled with the feature `par-iter`.*
 /// [`par_column_iter`]: crate::Matrix::par_column_iter
 /// [`Matrix`]: crate::Matrix
 #[cfg_attr(doc_cfg, doc(cfg(feature = "par-iter")))]
@@ -23,7 +23,7 @@ pub struct ParColumnIter<'a, T, R: Dim, Cols: Dim, S: RawStorage<T, R, Cols>> {
 }
 
 impl<'a, T, R: Dim, Cols: Dim, S: RawStorage<T, R, Cols>> ParColumnIter<'a, T, R, Cols, S> {
-    /// create a new parallel iterator for the given matrix
+    /// Create a new parallel iterator for the given matrix.
     fn new(matrix: &'a Matrix<T, R, Cols, S>) -> Self {
         Self { mat: matrix }
     }
@@ -51,7 +51,7 @@ where
 }
 
 #[cfg_attr(doc_cfg, doc(cfg(feature = "par-iter")))]
-/// *only availabe if compiled with the feature `par-iter`*
+/// *Only available if compiled with the feature `par-iter`.*
 impl<'a, T, R: Dim, Cols: Dim, S: RawStorage<T, R, Cols>> IndexedParallelIterator
     for ParColumnIter<'a, T, R, Cols, S>
 where
@@ -76,8 +76,8 @@ where
 }
 
 #[cfg_attr(doc_cfg, doc(cfg(feature = "par-iter")))]
-/// A rayon parallel iterator through the mutable columns of a matrix
+/// A rayon parallel iterator through the mutable columns of a matrix.
-/// *only availabe if compiled with the feature `par-iter`*
+/// *Only available if compiled with the feature `par-iter`.*
 pub struct ParColumnIterMut<
     'a,
     T,
@@ -96,14 +96,14 @@ where
     Cols: Dim,
     S: RawStorage<T, R, Cols> + RawStorageMut<T, R, Cols>,
 {
-    /// create a new parallel iterator for the given matrix
+    /// create a new parallel iterator for the given matrix.
     fn new(mat: &'a mut Matrix<T, R, Cols, S>) -> Self {
         Self { mat }
     }
 }
 
 #[cfg_attr(doc_cfg, doc(cfg(feature = "par-iter")))]
-/// *only availabe if compiled with the feature `par-iter`*
+/// *Only available if compiled with the feature `par-iter`*
 impl<'a, T, R, Cols, S> ParallelIterator for ParColumnIterMut<'a, T, R, Cols, S>
 where
     R: Dim,
@@ -126,7 +126,7 @@ where
 }
 
 #[cfg_attr(doc_cfg, doc(cfg(feature = "par-iter")))]
-/// *only availabe if compiled with the feature `par-iter`*
+/// *Only available if compiled with the feature `par-iter`*
 impl<'a, T, R, Cols, S> IndexedParallelIterator for ParColumnIterMut<'a, T, R, Cols, S>
 where
     R: Dim,
@@ -154,7 +154,7 @@ where
 
 #[cfg_attr(doc_cfg, doc(cfg(feature = "par-iter")))]
 /// # Parallel iterators using `rayon`
-/// *Only availabe if compiled with the feature `par-iter`*
+/// *Only available if compiled with the feature `par-iter`*
 impl<T, R: Dim, Cols: Dim, S: RawStorage<T, R, Cols>> Matrix<T, R, Cols, S>
 where
     T: Send + Sync + Scalar,
@@ -190,6 +190,7 @@ where
     pub fn par_column_iter(&self) -> ParColumnIter<'_, T, R, Cols, S> {
         ParColumnIter::new(self)
     }
+
     /// Mutably iterate through the columns of this matrix in parallel using rayon.
     /// Allows mutable access to the columns in parallel using mutable references.
     /// If mutable access to the columns is not required rather use [`par_column_iter`]
@@ -221,9 +222,9 @@ where
     }
 }
 
-/// a private helper newtype that wraps the `ColumnIter` and implements
+/// A private helper newtype that wraps the `ColumnIter` and implements
 /// the rayon `Producer` trait. It's just here so we don't have to make the
-/// rayon trait part of the public interface of the `ColumnIter`
+/// rayon trait part of the public interface of the `ColumnIter`.
 struct ColumnProducer<'a, T, R: Dim, C: Dim, S: RawStorage<T, R, C>>(ColumnIter<'a, T, R, C, S>);
 
 #[cfg_attr(doc_cfg, doc(cfg(feature = "par-iter")))]
@@ -238,24 +239,16 @@ where
     type IntoIter = ColumnIter<'a, T, R, Cols, S>;
 
     #[inline]
-    fn split_at(self, index: usize) -> (Self, Self) {
+    fn into_iter(self) -> Self::IntoIter {
-        // the index is relative to the size of this current iterator
+        self.0
-        // it will always start at zero so it serves as an offset
-        let left_iter = ColumnIter {
-            mat: self.0.mat,
-            range: self.0.range.start..(self.0.range.start + index),
-        };
-
-        let right_iter = ColumnIter {
-            mat: self.0.mat,
-            range: (self.0.range.start + index)..self.0.range.end,
-        };
-        (Self(left_iter), Self(right_iter))
     }
 
     #[inline]
-    fn into_iter(self) -> Self::IntoIter {
+    fn split_at(self, index: usize) -> (Self, Self) {
-        self.0
+        // The index is relative to the size of this current iterator.
+        // It will always start at zero so it serves as an offset.
+        let (left_iter, right_iter) = self.0.split_at(index);
+        (Self(left_iter), Self(right_iter))
     }
 }
 
@@ -279,20 +272,9 @@ where
     }
 
     fn split_at(self, index: usize) -> (Self, Self) {
-        // the index is relative to the size of this current iterator
+        // The index is relative to the size of this current iterator
-        // it will always start at zero so it serves as an offset
+        // it will always start at zero so it serves as an offset.
-
+        let (left_iter, right_iter) = self.0.split_at(index);
-        let left_iter = ColumnIterMut {
-            mat: self.0.mat,
-            range: self.0.range.start..(self.0.range.start + index),
-            phantom: Default::default(),
-        };
-
-        let right_iter = ColumnIterMut {
-            mat: self.0.mat,
-            range: (self.0.range.start + index)..self.0.range.end,
-            phantom: Default::default(),
-        };
         (Self(left_iter), Self(right_iter))
     }
 }

tests/lib.rs

@@ -9,10 +9,6 @@ compile_error!(
      Example: `cargo test --features debug,compare,rand,macros`"
 );
 
-// make sure to test the parallel iterators for all builds that do not require no_std
-#[cfg(all(feature = "std", not(feature = "par-iter")))]
-compile_error!("Please additionally enable the `par-iter` feature to compile and run the tests");
-
 #[cfg(all(feature = "debug", feature = "compare", feature = "rand"))]
 #[macro_use]
 extern crate approx;