Add AxisWindows

Move core logic of creating the Windows logic into seperate fn.
fix some bugs, make the tests pass

Reduce code duplication

Specialize the `Windows` struct with a `variant` field to replace the
`AxisWindows` struct

src/impl_methods.rs

@@ -46,6 +46,7 @@ use crate::iter::{
     AxisChunksIterMut,
     AxisIter,
     AxisIterMut,
+    AxisWindows,
     ExactChunks,
     ExactChunksMut,
     IndexedIter,
@@ -1521,7 +1522,7 @@ where
     ///     assert_eq!(window.shape(), &[4, 3, 2]);
     /// }
     /// ```
-    pub fn axis_windows(&self, axis: Axis, window_size: usize) -> Windows<'_, A, D>
+    pub fn axis_windows(&self, axis: Axis, window_size: usize) -> AxisWindows<'_, A, D>
     where S: Data
     {
         let axis_index = axis.index();
@@ -1537,10 +1538,7 @@ where
             self.shape()
         );
 
-        let mut size = self.raw_dim();
-        size[axis_index] = window_size;
-
-        Windows::new(self.view(), size)
+        AxisWindows::new(self.view(), axis, window_size)
     }
 
     // Return (length, stride) for diagonal

src/iterators/iter.rs

@@ -13,6 +13,7 @@ pub use crate::iterators::{
     AxisChunksIterMut,
     AxisIter,
     AxisIterMut,
+    AxisWindows,
     ExactChunks,
     ExactChunksIter,
     ExactChunksIterMut,

src/iterators/mod.rs

@@ -28,7 +28,7 @@ use super::{Dimension, Ix, Ixs};
 pub use self::chunks::{ExactChunks, ExactChunksIter, ExactChunksIterMut, ExactChunksMut};
 pub use self::into_iter::IntoIter;
 pub use self::lanes::{Lanes, LanesMut};
-pub use self::windows::Windows;
+pub use self::windows::{AxisWindows, Windows};
 
 use std::slice::{self, Iter as SliceIter, IterMut as SliceIterMut};
 

src/iterators/windows.rs

@@ -41,41 +41,7 @@ impl<'a, A, D: Dimension> Windows<'a, A, D>
         let strides = axis_strides.into_dimension();
         let window_strides = a.strides.clone();
 
-        ndassert!(
-            a.ndim() == window.ndim(),
-            concat!(
-                "Window dimension {} does not match array dimension {} ",
-                "(with array of shape {:?})"
-            ),
-            window.ndim(),
-            a.ndim(),
-            a.shape()
-        );
-
-        ndassert!(
-            a.ndim() == strides.ndim(),
-            concat!(
-                "Stride dimension {} does not match array dimension {} ",
-                "(with array of shape {:?})"
-            ),
-            strides.ndim(),
-            a.ndim(),
-            a.shape()
-        );
-
-        let mut base = a;
-        base.slice_each_axis_inplace(|ax_desc| {
-            let len = ax_desc.len;
-            let wsz = window[ax_desc.axis.index()];
-            let stride = strides[ax_desc.axis.index()];
-
-            if len < wsz {
-                Slice::new(0, Some(0), 1)
-            } else {
-                Slice::new(0, Some((len - wsz + 1) as isize), stride as isize)
-            }
-        });
-
+        let base = build_base(a, window.clone(), strides);
         Windows {
             base: base.into_raw_view(),
             life: PhantomData,
@@ -160,3 +126,166 @@ impl_iterator! {
 
 send_sync_read_only!(Windows);
 send_sync_read_only!(WindowsIter);
+
+/// Window producer and iterable
+///
+/// See [`.axis_windows()`](ArrayBase::axis_windows) for more
+/// information.
+pub struct AxisWindows<'a, A, D>
+{
+    base: ArrayView<'a, A, D>,
+    axis_idx: usize,
+    window: D,
+    strides: D,
+}
+
+impl<'a, A, D: Dimension> AxisWindows<'a, A, D>
+{
+    pub(crate) fn new(a: ArrayView<'a, A, D>, axis: Axis, window_size: usize) -> Self
+    {
+        let window_strides = a.strides.clone();
+        let axis_idx = axis.index();
+
+        let mut window = a.raw_dim();
+        window[axis_idx] = window_size;
+
+        let ndim = window.ndim();
+        let mut unit_stride = D::zeros(ndim);
+        unit_stride.slice_mut().fill(1);
+
+        let base = build_base(a, window.clone(), unit_stride);
+        AxisWindows {
+            base,
+            axis_idx,
+            window,
+            strides: window_strides,
+        }
+    }
+}
+
+impl<'a, A, D: Dimension> NdProducer for AxisWindows<'a, A, D>
+{
+    type Item = ArrayView<'a, A, D>;
+    type Dim = Ix1;
+    type Ptr = *mut A;
+    type Stride = isize;
+
+    fn raw_dim(&self) -> Ix1
+    {
+        Ix1(self.base.raw_dim()[self.axis_idx])
+    }
+
+    fn layout(&self) -> Layout
+    {
+        self.base.layout()
+    }
+
+    fn as_ptr(&self) -> *mut A
+    {
+        self.base.as_ptr() as *mut _
+    }
+
+    fn contiguous_stride(&self) -> isize
+    {
+        self.base.contiguous_stride()
+    }
+
+    unsafe fn as_ref(&self, ptr: *mut A) -> Self::Item
+    {
+        ArrayView::new_(ptr, self.window.clone(), self.strides.clone())
+    }
+
+    unsafe fn uget_ptr(&self, i: &Self::Dim) -> *mut A
+    {
+        let mut d = D::zeros(self.base.ndim());
+        d[self.axis_idx] = i[0];
+        self.base.uget_ptr(&d)
+    }
+
+    fn stride_of(&self, axis: Axis) -> isize
+    {
+        assert_eq!(axis, Axis(0));
+        self.base.stride_of(Axis(self.axis_idx))
+    }
+
+    fn split_at(self, axis: Axis, index: usize) -> (Self, Self)
+    {
+        assert_eq!(axis, Axis(0));
+        let (a, b) = self.base.split_at(Axis(self.axis_idx), index);
+        (
+            AxisWindows {
+                base: a,
+                axis_idx: self.axis_idx,
+                window: self.window.clone(),
+                strides: self.strides.clone(),
+            },
+            AxisWindows {
+                base: b,
+                axis_idx: self.axis_idx,
+                window: self.window,
+                strides: self.strides,
+            },
+        )
+    }
+
+    private_impl!{}
+}
+
+impl<'a, A, D> IntoIterator for AxisWindows<'a, A, D>
+where
+    D: Dimension,
+    A: 'a,
+{
+    type Item = <Self::IntoIter as Iterator>::Item;
+    type IntoIter = WindowsIter<'a, A, D>;
+    fn into_iter(self) -> Self::IntoIter
+    {
+        WindowsIter {
+            iter: self.base.into_base_iter(),
+            life: PhantomData,
+            window: self.window,
+            strides: self.strides,
+        }
+    }
+}
+
+/// build the base array of the `Windows` and `AxisWindows` structs
+fn build_base<A, D>(a: ArrayView<A, D>, window: D, strides: D) -> ArrayView<A, D>
+where D: Dimension
+{
+    ndassert!(
+        a.ndim() == window.ndim(),
+        concat!(
+            "Window dimension {} does not match array dimension {} ",
+            "(with array of shape {:?})"
+        ),
+        window.ndim(),
+        a.ndim(),
+        a.shape()
+    );
+
+    ndassert!(
+        a.ndim() == strides.ndim(),
+        concat!(
+            "Stride dimension {} does not match array dimension {} ",
+            "(with array of shape {:?})"
+        ),
+        strides.ndim(),
+        a.ndim(),
+        a.shape()
+    );
+
+    let mut base = a;
+    base.slice_each_axis_inplace(|ax_desc| {
+        let len = ax_desc.len;
+        let wsz = window[ax_desc.axis.index()];
+        let stride = strides[ax_desc.axis.index()];
+
+        if len < wsz {
+            Slice::new(0, Some(0), 1)
+        } else {
+            Slice::new(0, Some((len - wsz + 1) as isize), stride as isize)
+        }
+    });
+    base
+}