create separate newtype for producer trait

src/base/iter.rs

@@ -301,8 +301,8 @@ 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>> {
-    mat: &'a Matrix<T, R, C, S>,
+    pub(crate) mat: &'a Matrix<T, R, C, S>,
-    range: Range<usize>,
+    pub(crate) range: Range<usize>,
 }
 
 impl<'a, T, R: Dim, C: Dim, S: 'a + RawStorage<T, R, C>> ColumnIter<'a, T, R, C, S> {
@@ -370,9 +370,9 @@ 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>> {
-    mat: *mut Matrix<T, R, C, S>,
+    pub(crate) mat: *mut Matrix<T, R, C, S>,
-    phantom: PhantomData<&'a 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>>,
 }
 
 impl<'a, T, R: Dim, C: Dim, S: 'a + RawStorageMut<T, R, C>> ColumnIterMut<'a, T, R, C, S> {
@@ -443,81 +443,3 @@ impl<'a, T: Scalar, R: Dim, C: Dim, S: 'a + RawStorageMut<T, R, C>> DoubleEndedI
         }
     }
 }
-
-/// implementations for parallel iteration with rayon
-#[cfg(feature = "par-iter")]
-mod parallel {
-    use super::*;
-    use rayon::iter::plumbing::Producer;
-
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "par-iter")))]
-    /// *only available if compiled with the feature `par-iter`*
-    impl<'a, T, R: Dim, Cols: Dim, S: RawStorage<T, R, Cols>> Producer for ColumnIter<'a, T, R, Cols, S>
-    where
-        T: Send + Sync + Scalar,
-        S: Sync,
-    {
-        type Item = MatrixSlice<'a, T, R, U1, S::RStride, S::CStride>;
-        type IntoIter = ColumnIter<'a, T, R, Cols, S>;
-
-        fn split_at(self, index: usize) -> (Self, Self) {
-            // 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 = Self {
-                mat: self.mat,
-                range: self.range.start..(self.range.start + index),
-            };
-
-            let right = Self {
-                mat: self.mat,
-                range: (self.range.start + index)..self.range.end,
-            };
-            (left, right)
-        }
-
-        fn into_iter(self) -> Self::IntoIter {
-            self
-        }
-    }
-
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "par-iter")))]
-    /// *only available if compiled with the feature `par-iter`*
-    impl<'a, T, R: Dim, C: Dim, S: 'a + RawStorageMut<T, R, C>> Producer
-        for ColumnIterMut<'a, T, R, C, S>
-    where
-        T: Send + Sync + Scalar,
-        S: Send + Sync,
-    {
-        type Item = MatrixSliceMut<'a, T, R, U1, S::RStride, S::CStride>;
-        type IntoIter = ColumnIterMut<'a, T, R, C, S>;
-
-        fn into_iter(self) -> Self::IntoIter {
-            self
-        }
-
-        fn split_at(self, index: usize) -> (Self, Self) {
-            // 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 = Self {
-                mat: self.mat,
-                range: self.range.start..(self.range.start + index),
-                phantom: Default::default(),
-            };
-
-            let right = Self {
-                mat: self.mat,
-                range: (self.range.start + index)..self.range.end,
-                phantom: Default::default(),
-            };
-            (left, right)
-        }
-    }
-
-    /// this implementation is safe because we are enforcing exclusive access
-    /// to the columns through the active range of the iterator
-    unsafe impl<'a, T: Scalar, R: Dim, C: Dim, S: 'a + RawStorageMut<T, R, C>> Send
-        for ColumnIterMut<'a, T, R, C, S>
-    {
-    }
-}

src/base/par_iter.rs

@@ -9,6 +9,7 @@ use crate::{
     Dim, Matrix, MatrixSlice, MatrixSliceMut, RawStorage, RawStorageMut, Scalar, U1,
 };
 use rayon::{iter::plumbing::bridge, prelude::*};
+use rayon::iter::plumbing::Producer;
 
 /// A rayon parallel iterator over the colums of a matrix. It is created
 /// using the [`par_column_iter`] method of [`Matrix`].
@@ -69,7 +70,7 @@ where
         self,
         callback: CB,
     ) -> CB::Output {
-        let producer = ColumnIter::new(self.mat);
+        let producer = ColumnProducer(ColumnIter::new(self.mat));
         callback.callback(producer)
     }
 }
@@ -146,7 +147,7 @@ where
         self,
         callback: CB,
     ) -> CB::Output {
-        let producer = ColumnIterMut::new(self.mat);
+        let producer = ColumnProducerMut(ColumnIterMut::new(self.mat));
         callback.callback(producer)
     }
 }
@@ -219,3 +220,84 @@ where
         ParColumnIterMut::new(self)
     }
 }
+
+/// 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`
+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")))]
+/// *only available if compiled with the feature `par-iter`*
+impl<'a, T, R: Dim, Cols: Dim, S: RawStorage<T, R, Cols>> Producer for ColumnProducer<'a, T, R, Cols, S>
+where
+T: Send + Sync + Scalar,
+S: Sync,
+{
+    type Item = MatrixSlice<'a, T, R, U1, S::RStride, S::CStride>;
+    type IntoIter = ColumnIter<'a, T, R, Cols, S>;
+    
+    #[inline]
+    fn split_at(self, index: usize) -> (Self, Self) {
+        // 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 = 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 {
+        self.0
+    }
+}
+
+/// See `ColumnProducer`. A private wrapper newtype that keeps the Producer
+/// implementation private
+struct ColumnProducerMut<'a, T, R: Dim, C: Dim, S: RawStorageMut<T, R, C>>(ColumnIterMut<'a,T,R,C,S>);
+
+impl<'a, T, R: Dim, C: Dim, S: 'a + RawStorageMut<T, R, C>> Producer
+for ColumnProducerMut<'a, T, R, C, S>
+where
+T: Send + Sync + Scalar,
+S: Send + Sync,
+{
+    type Item = MatrixSliceMut<'a, T, R, U1, S::RStride, S::CStride>;
+    type IntoIter = ColumnIterMut<'a, T, R, C, S>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.0
+    }
+
+    fn split_at(self, index: usize) -> (Self, Self) {
+        // 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 = 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))
+    }
+}
+
+
+/// this implementation is safe because we are enforcing exclusive access
+/// to the columns through the active range of the iterator
+unsafe impl<'a, T: Scalar, R: Dim, C: Dim, S: 'a + RawStorageMut<T, R, C>> Send
+for ColumnIterMut<'a, T, R, C, S>
+{
+}