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// Copyright 2014-2016 bluss and ndarray developers.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
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 {
ElementsBase,
ElementsBaseMut,
Iter,
IterMut,
Baseiter,
};
use iter::{self, AxisIter, AxisIterMut};
/// Returns `true` if the pointer is aligned.
fn is_aligned<T>(ptr: *const T) -> bool {
(ptr as usize) % ::std::mem::align_of::<T>() == 0
}
/// Methods for read-only array views.
impl<'a, A, D> ArrayView<'a, A, D>
where D: Dimension,
{
/// Create a read-only array view borrowing its data from a slice.
///
/// Checks whether `shape` are compatible with the slice's
/// length, returning an `Err` if not compatible.
///
/// ```
/// use ndarray::ArrayView;
/// use ndarray::arr3;
/// use ndarray::ShapeBuilder;
///
/// let s = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
/// let a = ArrayView::from_shape((2, 3, 2).strides((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_shape<Sh>(shape: Sh, xs: &'a [A])
-> Result<Self, ShapeError>
where Sh: Into<StrideShape<D>>,
{
// eliminate the type parameter Sh as soon as possible
Self::from_shape_impl(shape.into(), xs)
}
fn from_shape_impl(shape: StrideShape<D>, xs: &'a [A]) -> Result<Self, ShapeError> {
let dim = shape.dim;
let strides = shape.strides;
if shape.custom {
dimension::can_index_slice(xs, &dim, &strides)?;
} else {
dimension::can_index_slice_not_custom::<A, _>(xs, &dim)?;
}
unsafe { Ok(Self::new_(xs.as_ptr(), dim, strides)) }
}
/// Create an `ArrayView<A, D>` from shape information and a raw pointer to
/// the elements.
///
/// Unsafe because caller is responsible for ensuring all of the following:
///
/// * The elements seen by moving `ptr` according to the shape and strides
/// must live at least as long as `'a` and must not be not mutably
/// aliased for the duration of `'a`.
///
/// * `ptr` must be non-null and aligned, and it must be safe to
/// [`.offset()`] `ptr` by zero.
///
/// * It must be safe to [`.offset()`] the pointer repeatedly along all
/// axes and calculate the `count`s for the `.offset()` calls without
/// overflow, even if the array is empty or the elements are zero-sized.
///
/// In other words,
///
/// * All possible pointers generated by moving along all axes must be in
/// bounds or one byte past the end of a single allocation with element
/// type `A`. The only exceptions are if the array is empty or the element
/// type is zero-sized. In these cases, `ptr` may be dangling, but it must
/// still be safe to [`.offset()`] the pointer along the axes.
///
/// * The offset in units of bytes between the least address and greatest
/// address by moving along all axes must not exceed `isize::MAX`. This
/// constraint prevents the computed offset, in bytes, from overflowing
/// `isize` regardless of the starting point due to past offsets.
///
/// * The offset in units of `A` between the least address and greatest
/// address by moving along all axes must not exceed `isize::MAX`. This
/// constraint prevents overflow when calculating the `count` parameter to
/// [`.offset()`] regardless of the starting point due to past offsets.
///
/// * The product of non-zero axis lengths must not exceed `isize::MAX`.
///
/// [`.offset()`]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset
pub unsafe fn from_shape_ptr<Sh>(shape: Sh, ptr: *const A) -> Self
where Sh: Into<StrideShape<D>>
{
let shape = shape.into();
let dim = shape.dim;
let strides = shape.strides;
if cfg!(debug_assertions) {
assert!(!ptr.is_null(), "The pointer must be non-null.");
assert!(is_aligned(ptr), "The pointer must be aligned.");
dimension::max_abs_offset_check_overflow::<A, _>(&dim, &strides).unwrap();
}
ArrayView::new_(ptr, dim, strides)
}
/// Convert the view into an `ArrayView<'b, A, D>` where `'b` is a lifetime
/// outlived by `'a'`.
pub fn reborrow<'b>(self) -> ArrayView<'b, A, D>
where 'a: 'b
{
unsafe {
ArrayView::new_(self.as_ptr(), self.dim, self.strides)
}
}
/// Split the array view 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.
///
/// Below, an illustration of `.split_at(Axis(2), 2)` on
/// an array with shape 3 × 5 × 5.
///
/// <img src="https://rust-ndarray.github.io/ndarray/images/split_at.svg" width="300px" height="271px">
pub fn split_at(self, axis: Axis, index: Ix)
-> (Self, Self)
{
// NOTE: Keep this in sync with the ArrayViewMut version
assert!(index <= self.len_of(axis));
let left_ptr = self.ptr;
let right_ptr = if index == self.len_of(axis) {
self.ptr
} else {
let offset = stride_offset(index, self.strides.axis(axis));
unsafe {
self.ptr.offset(offset)
}
};
let mut dim_left = self.dim.clone();
dim_left.set_axis(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.axis(axis) - index;
dim_right.set_axis(axis, right_len);
let right = unsafe {
Self::new_(right_ptr, dim_right, self.strides)
};
(left, right)
}
/// Return the array’s data as a slice, if it is contiguous and in standard order.
/// Return `None` otherwise.
pub fn into_slice(&self) -> Option<&'a [A]> {
if self.is_standard_layout() {
unsafe {
Some(slice::from_raw_parts(self.ptr, self.len()))
}
} else {
None
}
}
}
/// Extra indexing methods for array views
///
/// These methods are very similar to regular indexing or calling of the
/// `get`/`get_mut` methods that we can use on any array or array view. The
/// difference here is in the length of lifetime in the resulting reference.
///
/// **Note** that the `ArrayView` (read-only) and `ArrayViewMut` (read-write) differ
/// in how they are allowed implement this trait -- `ArrayView`'s implementation
/// is usual. If you put in a `ArrayView<'a, T, D>` here, you get references
/// `&'a T` out.
///
/// For `ArrayViewMut` to obey the borrowing rules we have to consume the
/// view if we call any of these methods. (The equivalent of reborrow is
/// `.view_mut()` for read-write array views, but if you can use that,
/// then the regular indexing / `get_mut` should suffice, too.)
///
/// ```
/// use ndarray::IndexLonger;
/// use ndarray::ArrayView;
///
/// let data = [0.; 256];
/// let long_life_ref = {
/// // make a 16 × 16 array view
/// let view = ArrayView::from(&data[..]).into_shape((16, 16)).unwrap();
///
/// // index the view and with `IndexLonger`.
/// // Note here that we get a reference with a life that is derived from
/// // `data`, the base data, instead of being derived from the view
/// IndexLonger::index(&view, [0, 1])
/// };
///
/// // view goes out of scope
///
/// assert_eq!(long_life_ref, &0.);
///
/// ```
pub trait IndexLonger<I> {
/// The type of the reference to the element that is produced, including
/// its lifetime.
type Output;
/// 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 only do for the array view and not in the
/// `Index` trait.
///
/// See also [the `get` method][1] which works for all arrays and array
/// views.
///
/// [1]: struct.ArrayBase.html#method.get
///
/// **Panics** if index is out of bounds.
fn index(self, index: I) -> Self::Output;
/// Get a reference of a element through the view.
///
/// This method is like `ArrayBase::get` but with a longer lifetime (matching
/// the array view); which we can only do for the array view and not in the
/// `Index` trait.
///
/// See also [the `get` method][1] (and [`get_mut`][2]) which works for all arrays and array
/// views.
///
/// [1]: struct.ArrayBase.html#method.get
/// [2]: struct.ArrayBase.html#method.get_mut
///
/// **Panics** if index is out of bounds.
fn get(self, index: I) -> Option<Self::Output>;
/// 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.
///
/// See also [the `uget` method][1] which works for all arrays and array
/// views.
///
/// [1]: struct.ArrayBase.html#method.uget
///
/// **Note:** only unchecked for non-debug builds of ndarray.
unsafe fn uget(self, index: I) -> Self::Output;
}
impl<'a, 'b, I, A, D> IndexLonger<I> for &'b ArrayView<'a, A, D>
where I: NdIndex<D>,
D: Dimension,
{
type Output = &'a A;
/// 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 only do for the array view and not in the
/// `Index` trait.
///
/// See also [the `get` method][1] which works for all arrays and array
/// views.
///
/// [1]: struct.ArrayBase.html#method.get
///
/// **Panics** if index is out of bounds.
fn index(self, index: I) -> &'a A
{
debug_bounds_check!(self, index);
unsafe {
&*self.get_ptr(index).unwrap_or_else(|| array_out_of_bounds())
}
}
fn get(self, index: I) -> Option<&'a A>
{
unsafe {
self.get_ptr(index).map(|ptr| &*ptr)
}
}
/// 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.
///
/// See also [the `uget` method][1] which works for all arrays and array
/// views.
///
/// [1]: struct.ArrayBase.html#method.uget
///
/// **Note:** only unchecked for non-debug builds of ndarray.
unsafe fn uget(self, index: I) -> &'a A
{
debug_bounds_check!(self, index);
&*self.as_ptr().offset(index.index_unchecked(&self.strides))
}
}
/// Methods for read-write array views.
impl<'a, A, D> ArrayViewMut<'a, 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;
/// use ndarray::ShapeBuilder;
///
/// let mut s = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
/// let mut a = ArrayViewMut::from_shape((2, 3, 2).strides((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_shape<Sh>(shape: Sh, xs: &'a mut [A])
-> Result<Self, ShapeError>
where Sh: Into<StrideShape<D>>,
{
// eliminate the type parameter Sh as soon as possible
Self::from_shape_impl(shape.into(), xs)
}
fn from_shape_impl(shape: StrideShape<D>, xs: &'a mut [A]) -> Result<Self, ShapeError> {
let dim = shape.dim;
let strides = shape.strides;
if shape.custom {
dimension::can_index_slice(xs, &dim, &strides)?;
} else {
dimension::can_index_slice_not_custom::<A, _>(xs, &dim)?;
}
unsafe { Ok(Self::new_(xs.as_mut_ptr(), dim, strides)) }
}
/// Create an `ArrayViewMut<A, D>` from shape information and a
/// raw pointer to the elements.
///
/// Unsafe because caller is responsible for ensuring all of the following:
///
/// * The elements seen by moving `ptr` according to the shape and strides
/// must live at least as long as `'a` and must not be aliased for the
/// duration of `'a`.
///
/// * `ptr` must be non-null and aligned, and it must be safe to
/// [`.offset()`] `ptr` by zero.
///
/// * It must be safe to [`.offset()`] the pointer repeatedly along all
/// axes and calculate the `count`s for the `.offset()` calls without
/// overflow, even if the array is empty or the elements are zero-sized.
///
/// In other words,
///
/// * All possible pointers generated by moving along all axes must be in
/// bounds or one byte past the end of a single allocation with element
/// type `A`. The only exceptions are if the array is empty or the element
/// type is zero-sized. In these cases, `ptr` may be dangling, but it must
/// still be safe to [`.offset()`] the pointer along the axes.
///
/// * The offset in units of bytes between the least address and greatest
/// address by moving along all axes must not exceed `isize::MAX`. This
/// constraint prevents the computed offset, in bytes, from overflowing
/// `isize` regardless of the starting point due to past offsets.
///
/// * The offset in units of `A` between the least address and greatest
/// address by moving along all axes must not exceed `isize::MAX`. This
/// constraint prevents overflow when calculating the `count` parameter to
/// [`.offset()`] regardless of the starting point due to past offsets.
///
/// * The product of non-zero axis lengths must not exceed `isize::MAX`.
///
/// [`.offset()`]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset
pub unsafe fn from_shape_ptr<Sh>(shape: Sh, ptr: *mut A) -> Self
where Sh: Into<StrideShape<D>>
{
let shape = shape.into();
let dim = shape.dim;
let strides = shape.strides;
if cfg!(debug_assertions) {
assert!(!ptr.is_null(), "The pointer must be non-null.");
assert!(is_aligned(ptr), "The pointer must be aligned.");
dimension::max_abs_offset_check_overflow::<A, _>(&dim, &strides).unwrap();
}
ArrayViewMut::new_(ptr, dim, strides)
}
/// Convert the view into an `ArrayViewMut<'b, A, D>` where `'b` is a lifetime
/// outlived by `'a'`.
pub fn reborrow<'b>(mut self) -> ArrayViewMut<'b, A, D>
where 'a: 'b
{
unsafe {
ArrayViewMut::new_(self.as_mut_ptr(), self.dim, self.strides)
}
}
/// Split the array view 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
assert!(index <= self.len_of(axis));
let left_ptr = self.ptr;
let right_ptr = if index == self.len_of(axis) {
self.ptr
} else {
let offset = stride_offset(index, self.strides.axis(axis));
unsafe {
self.ptr.offset(offset)
}
};
let mut dim_left = self.dim.clone();
dim_left.set_axis(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.axis(axis) - index;
dim_right.set_axis(axis, right_len);
let right = unsafe {
Self::new_(right_ptr, dim_right, self.strides)
};
(left, right)
}
/// Return the array’s data as a slice, if it is contiguous and in standard order.
/// Return `None` otherwise.
pub fn into_slice(self) -> Option<&'a mut [A]> {
self.into_slice_().ok()
}
}
impl<'a, I, A, D> IndexLonger<I> for ArrayViewMut<'a, A, D>
where I: NdIndex<D>,
D: Dimension,
{
type Output = &'a mut A;
/// Convert a mutable array view to a mutable reference of a element.
///
/// This method is like `IndexMut::index_mut` but with a longer lifetime
/// (matching the array view); which we can only do for the array view and
/// not in the `Index` trait.
///
/// See also [the `get_mut` method][1] which works for all arrays and array
/// views.
///
/// [1]: struct.ArrayBase.html#method.get_mut
///
/// **Panics** if index is out of bounds.
fn index(mut self, index: I) -> &'a mut A {
debug_bounds_check!(self, index);
unsafe {
match self.get_ptr_mut(index) {
Some(ptr) => &mut *ptr,
None => array_out_of_bounds(),
}
}
}
/// Convert a mutable array view to a mutable reference of a element, with
/// checked access.
///
/// See also [the `get_mut` method][1] which works for all arrays and array
/// views.
///
/// [1]: struct.ArrayBase.html#method.get_mut
///
fn get(mut self, index: I) -> Option<&'a mut A> {
debug_bounds_check!(self, index);
unsafe {
match self.get_ptr_mut(index) {
Some(ptr) => Some(&mut *ptr),
None => None,
}
}
}
/// Convert a mutable array view to a mutable reference of a element without
/// boundary check.
///
/// See also [the `uget_mut` method][1] which works for all arrays and array
/// views.
///
/// [1]: struct.ArrayBase.html#method.uget_mut
///
/// **Note:** only unchecked for non-debug builds of ndarray.
unsafe fn uget(mut self, index: I) -> &'a mut A {
debug_bounds_check!(self, index);
&mut *self.as_mut_ptr().offset(index.index_unchecked(&self.strides))
}
}
/// Private array view methods
impl<'a, A, D> ArrayView<'a, A, D>
where D: Dimension,
{
/// Create a new `ArrayView`
///
/// Unsafe because: `ptr` must be valid for the given dimension and strides.
#[inline(always)]
pub(crate) unsafe fn new_(ptr: *const A, dim: D, strides: D) -> Self {
ArrayView {
data: ViewRepr::new(),
ptr: ptr as *mut A,
dim: dim,
strides: strides,
}
}
#[inline]
pub(crate) fn into_base_iter(self) -> Baseiter<A, D> {
unsafe {
Baseiter::new(self.ptr, self.dim, self.strides)
}
}
#[inline]
pub(crate) fn into_elements_base(self) -> ElementsBase<'a, A, D> {
ElementsBase::new(self)
}
pub(crate) fn into_iter_(self) -> Iter<'a, A, D> {
Iter::new(self)
}
/// Return an outer iterator for this view.
#[doc(hidden)] // not official
#[deprecated(note="This method will be replaced.")]
pub fn into_outer_iter(self) -> iter::AxisIter<'a, A, D::Smaller>
where D: RemoveAxis,
{
AxisIter::new(self, Axis(0))
}
}
impl<'a, A, D> ArrayViewMut<'a, A, D>
where D: Dimension,
{
/// Create a new `ArrayView`
///
/// Unsafe because: `ptr` must be valid for the given dimension and strides.
#[inline(always)]
pub(crate) unsafe fn new_(ptr: *mut A, dim: D, strides: D) -> Self {
if cfg!(debug_assertions) {
assert!(!ptr.is_null(), "The pointer must be non-null.");
assert!(is_aligned(ptr), "The pointer must be aligned.");
dimension::max_abs_offset_check_overflow::<A, _>(&dim, &strides).unwrap();
}
ArrayViewMut {
data: ViewRepr::new(),
ptr: ptr,
dim: dim,
strides: strides,
}
}
// Convert into a read-only view
pub(crate) fn into_view(self) -> ArrayView<'a, A, D> {
unsafe {
ArrayView::new_(self.ptr, self.dim, self.strides)
}
}
#[inline]
pub(crate) fn into_base_iter(self) -> Baseiter<A, D> {
unsafe {
Baseiter::new(self.ptr, self.dim, self.strides)
}
}
#[inline]
pub(crate) fn into_elements_base(self) -> ElementsBaseMut<'a, A, D> {
ElementsBaseMut::new(self)
}
pub(crate) fn into_slice_(self) -> Result<&'a mut [A], Self> {
if self.is_standard_layout() {
unsafe {
Ok(slice::from_raw_parts_mut(self.ptr, self.len()))
}
} else {
Err(self)
}
}
pub(crate) fn into_iter_(self) -> IterMut<'a, A, D> {
IterMut::new(self)
}
/// Return an outer iterator for this view.
#[doc(hidden)] // not official
#[deprecated(note="This method will be replaced.")]
pub fn into_outer_iter(self) -> iter::AxisIterMut<'a, A, D::Smaller>
where D: RemoveAxis,
{
AxisIterMut::new(self, Axis(0))
}
}