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use imp_prelude::*;
use dimension::{self, stride_offset};
use error::ShapeError;
/// # Methods for Array Views
///
/// Methods for read-only array views `ArrayView<'a, A, D>`
///
/// Note that array views implement traits like [`From`][f] and `IntoIterator` too.
/// [f]: #method.from
impl<'a, A, D> ArrayBase<ViewRepr<&'a A>, D>
where D: Dimension,
{
/// Create a read-only array view borrowing its data from a slice.
///
/// Checks whether `dim` and `strides` are compatible with the slice's
/// length, returning an `Err` if not compatible.
///
/// ```
/// use ndarray::ArrayView;
/// use ndarray::arr3;
///
/// let s = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
/// let a = ArrayView::from_slice_dim_stride((2, 3, 2),
/// (1, 4, 2),
/// &s).unwrap();
///
/// assert!(
/// a == arr3(&[[[0, 2],
/// [4, 6],
/// [8, 10]],
/// [[1, 3],
/// [5, 7],
/// [9, 11]]])
/// );
/// assert!(a.strides() == &[1, 4, 2]);
/// ```
pub fn from_slice_dim_stride(dim: D, strides: D, xs: &'a [A])
-> Result<Self, ShapeError>
{
dimension::can_index_slice(xs, &dim, &strides).map(|_| {
unsafe {
Self::new_(xs.as_ptr(), dim, strides)
}
})
}
/// Split the array along `axis` and return one view strictly before the
/// split and one view after the split.
///
/// **Panics** if `axis` or `index` is out of bounds.
pub fn split_at(self, axis: Axis, index: Ix)
-> (Self, Self)
{
// NOTE: Keep this in sync with the ArrayViewMut version
let axis = axis.axis();
assert!(index <= self.shape()[axis]);
let left_ptr = self.ptr;
let right_ptr = if index == self.shape()[axis] {
self.ptr
} else {
let offset = stride_offset(index, self.strides.slice()[axis]);
unsafe {
self.ptr.offset(offset)
}
};
let mut dim_left = self.dim.clone();
dim_left.slice_mut()[axis] = index;
let left = unsafe {
Self::new_(left_ptr, dim_left, self.strides.clone())
};
let mut dim_right = self.dim;
let right_len = dim_right.slice()[axis] - index;
dim_right.slice_mut()[axis] = right_len;
let right = unsafe {
Self::new_(right_ptr, dim_right, self.strides)
};
(left, right)
}
}
/// Methods for read-write array views `ArrayViewMut<'a, A, D>`
///
/// Note that array views implement traits like [`From`][f] and `IntoIterator` too.
///
/// [f]: #method.from
impl<'a, A, D> ArrayBase<ViewRepr<&'a mut A>, D>
where D: Dimension,
{
/// Create a read-write array view borrowing its data from a slice.
///
/// Checks whether `dim` and `strides` are compatible with the slice's
/// length, returning an `Err` if not compatible.
///
/// ```
/// use ndarray::ArrayViewMut;
/// use ndarray::arr3;
///
/// let mut s = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
/// let mut a = ArrayViewMut::from_slice_dim_stride((2, 3, 2),
/// (1, 4, 2),
/// &mut s).unwrap();
///
/// a[[0, 0, 0]] = 1;
/// assert!(
/// a == arr3(&[[[1, 2],
/// [4, 6],
/// [8, 10]],
/// [[1, 3],
/// [5, 7],
/// [9, 11]]])
/// );
/// assert!(a.strides() == &[1, 4, 2]);
/// ```
pub fn from_slice_dim_stride(dim: D, strides: D, xs: &'a mut [A])
-> Result<Self, ShapeError>
{
dimension::can_index_slice(xs, &dim, &strides).map(|_| {
unsafe {
Self::new_(xs.as_mut_ptr(), dim, strides)
}
})
}
/// Split the array along `axis` and return one mutable view strictly
/// before the split and one mutable view after the split.
///
/// **Panics** if `axis` or `index` is out of bounds.
pub fn split_at(self, axis: Axis, index: Ix)
-> (Self, Self)
{
// NOTE: Keep this in sync with the ArrayView version
let axis = axis.axis();
assert!(index <= self.shape()[axis]);
let left_ptr = self.ptr;
let right_ptr = if index == self.shape()[axis] {
self.ptr
}
else {
let offset = stride_offset(index, self.strides.slice()[axis]);
unsafe {
self.ptr.offset(offset)
}
};
let mut dim_left = self.dim.clone();
dim_left.slice_mut()[axis] = index;
let left = unsafe {
Self::new_(left_ptr, dim_left, self.strides.clone())
};
let mut dim_right = self.dim;
let right_len = dim_right.slice()[axis] - index;
dim_right.slice_mut()[axis] = right_len;
let right = unsafe {
Self::new_(right_ptr, dim_right, self.strides)
};
(left, right)
}
}