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//! Abstract definition of a matrix data storage.
use std::ptr;
use crate::base::allocator::{Allocator, SameShapeC, SameShapeR};
use crate::base::default_allocator::DefaultAllocator;
use crate::base::dimension::{Dim, U1};
use crate::base::Scalar;
/*
* Aliases for allocation results.
*/
/// The data storage for the sum of two matrices with dimensions `(R1, C1)` and `(R2, C2)`.
pub type SameShapeStorage<T, R1, C1, R2, C2> =
<DefaultAllocator as Allocator<SameShapeR<R1, R2>, SameShapeC<C1, C2>>>::Buffer<T>;
// TODO: better name than Owned ?
/// The owned data storage that can be allocated from `S`.
pub type Owned<T, R, C = U1> = <DefaultAllocator as Allocator<R, C>>::Buffer<T>;
/// The owned data storage that can be allocated from `S`.
pub type OwnedUninit<T, R, C = U1> = <DefaultAllocator as Allocator<R, C>>::BufferUninit<T>;
/// The row-stride of the owned data storage for a buffer of dimension `(R, C)`.
pub type RStride<T, R, C = U1> =
<<DefaultAllocator as Allocator<R, C>>::Buffer<T> as RawStorage<T, R, C>>::RStride;
/// The column-stride of the owned data storage for a buffer of dimension `(R, C)`.
pub type CStride<T, R, C = U1> =
<<DefaultAllocator as Allocator<R, C>>::Buffer<T> as RawStorage<T, R, C>>::CStride;
/// The trait shared by all matrix data storage.
///
/// TODO: doc
/// # Safety
///
/// In generic code, it is recommended use the `Storage` trait bound instead. The `RawStorage`
/// trait bound is generally used by code that needs to work with storages that contains
/// `MaybeUninit<T>` elements.
///
/// Note that `Self` must always have a number of elements compatible with the matrix length (given
/// by `R` and `C` if they are known at compile-time). For example, implementors of this trait
/// should **not** allow the user to modify the size of the underlying buffer with safe methods
/// (for example the `VecStorage::data_mut` method is unsafe because the user could change the
/// vector's size so that it no longer contains enough elements: this will lead to UB.
pub unsafe trait RawStorage<T, R: Dim, C: Dim = U1>: Sized {
/// The static stride of this storage's rows.
type RStride: Dim;
/// The static stride of this storage's columns.
type CStride: Dim;
/// The matrix data pointer.
fn ptr(&self) -> *const T;
/// The dimension of the matrix at run-time. Arr length of zero indicates the additive identity
/// element of any dimension. Must be equal to `Self::dimension()` if it is not `None`.
fn shape(&self) -> (R, C);
/// The spacing between consecutive row elements and consecutive column elements.
///
/// For example this returns `(1, 5)` for a column-major matrix with 5 columns.
fn strides(&self) -> (Self::RStride, Self::CStride);
/// Compute the index corresponding to the irow-th row and icol-th column of this matrix. The
/// index must be such that the following holds:
///
/// ```ignore
/// let lindex = self.linear_index(irow, icol);
/// assert!(*self.get_unchecked(irow, icol) == *self.get_unchecked_linear(lindex))
/// ```
#[inline]
fn linear_index(&self, irow: usize, icol: usize) -> usize {
let (rstride, cstride) = self.strides();
irow * rstride.value() + icol * cstride.value()
}
/// Gets the address of the i-th matrix component without performing bound-checking.
///
/// # Safety
/// If the index is out of bounds, dereferencing the result will cause undefined behavior.
#[inline]
fn get_address_unchecked_linear(&self, i: usize) -> *const T {
self.ptr().wrapping_add(i)
}
/// Gets the address of the i-th matrix component without performing bound-checking.
///
/// # Safety
/// If the index is out of bounds, dereferencing the result will cause undefined behavior.
#[inline]
fn get_address_unchecked(&self, irow: usize, icol: usize) -> *const T {
self.get_address_unchecked_linear(self.linear_index(irow, icol))
}
/// Retrieves a reference to the i-th element without bound-checking.
///
/// # Safety
/// If the index is out of bounds, the method will cause undefined behavior.
#[inline]
unsafe fn get_unchecked_linear(&self, i: usize) -> &T {
&*self.get_address_unchecked_linear(i)
}
/// Retrieves a reference to the i-th element without bound-checking.
///
/// # Safety
/// If the index is out of bounds, the method will cause undefined behavior.
#[inline]
unsafe fn get_unchecked(&self, irow: usize, icol: usize) -> &T {
self.get_unchecked_linear(self.linear_index(irow, icol))
}
/// Indicates whether this data buffer stores its elements contiguously.
///
/// # Safety
/// This function must not return `true` if the underlying storage is not contiguous,
/// or undefined behaviour will occur.
fn is_contiguous(&self) -> bool;
/// Retrieves the data buffer as a contiguous slice.
///
/// # Safety
/// The matrix components may not be stored in a contiguous way, depending on the strides.
/// This method is unsafe because this can yield to invalid aliasing when called on some pairs
/// of matrix views originating from the same matrix with strides.
///
/// Call the safe alternative `matrix.as_slice()` instead.
unsafe fn as_slice_unchecked(&self) -> &[T];
}
/// Trait shared by all matrix data storage that don’t contain any uninitialized elements.
///
/// # Safety
///
/// Note that `Self` must always have a number of elements compatible with the matrix length (given
/// by `R` and `C` if they are known at compile-time). For example, implementors of this trait
/// should **not** allow the user to modify the size of the underlying buffer with safe methods
/// (for example the `VecStorage::data_mut` method is unsafe because the user could change the
/// vector's size so that it no longer contains enough elements: this will lead to UB.
pub unsafe trait Storage<T: Scalar, R: Dim, C: Dim = U1>: RawStorage<T, R, C> {
/// Builds a matrix data storage that does not contain any reference.
fn into_owned(self) -> Owned<T, R, C>
where
DefaultAllocator: Allocator<R, C>;
/// Clones this data storage to one that does not contain any reference.
fn clone_owned(&self) -> Owned<T, R, C>
where
DefaultAllocator: Allocator<R, C>;
/// Drops the storage without calling the destructors on the contained elements.
fn forget_elements(self);
}
/// Trait implemented by matrix data storage that can provide a mutable access to its elements.
///
/// # Safety
///
/// In generic code, it is recommended use the `StorageMut` trait bound instead. The
/// `RawStorageMut` trait bound is generally used by code that needs to work with storages that
/// contains `MaybeUninit<T>` elements.
///
/// Note that a mutable access does not mean that the matrix owns its data. For example, a mutable
/// matrix view can provide mutable access to its elements even if it does not own its data (it
/// contains only an internal reference to them).
pub unsafe trait RawStorageMut<T, R: Dim, C: Dim = U1>: RawStorage<T, R, C> {
/// The matrix mutable data pointer.
fn ptr_mut(&mut self) -> *mut T;
/// Gets the mutable address of the i-th matrix component without performing bound-checking.
///
/// # Safety
/// If the index is out of bounds, dereferencing the result will cause undefined behavior.
#[inline]
fn get_address_unchecked_linear_mut(&mut self, i: usize) -> *mut T {
self.ptr_mut().wrapping_add(i)
}
/// Gets the mutable address of the i-th matrix component without performing bound-checking.
///
/// # Safety
/// If the index is out of bounds, dereferencing the result will cause undefined behavior.
#[inline]
fn get_address_unchecked_mut(&mut self, irow: usize, icol: usize) -> *mut T {
let lid = self.linear_index(irow, icol);
self.get_address_unchecked_linear_mut(lid)
}
/// Retrieves a mutable reference to the i-th element without bound-checking.
///
/// # Safety
/// If the index is out of bounds, the method will cause undefined behavior.
unsafe fn get_unchecked_linear_mut(&mut self, i: usize) -> &mut T {
&mut *self.get_address_unchecked_linear_mut(i)
}
/// Retrieves a mutable reference to the element at `(irow, icol)` without bound-checking.
///
/// # Safety
/// If the index is out of bounds, the method will cause undefined behavior.
#[inline]
unsafe fn get_unchecked_mut(&mut self, irow: usize, icol: usize) -> &mut T {
&mut *self.get_address_unchecked_mut(irow, icol)
}
/// Swaps two elements using their linear index without bound-checking.
///
/// # Safety
/// If the indices are out of bounds, the method will cause undefined behavior.
///
/// # Validity
/// The default implementation of this trait function is only guaranteed to be
/// sound if invocations of `self.ptr_mut()` and `self.get_address_unchecked_linear_mut()`
/// result in stable references. If any of the data pointed to by these trait methods
/// moves as a consequence of invoking either of these methods then this default
/// trait implementation may be invalid or unsound and should be overridden.
#[inline]
unsafe fn swap_unchecked_linear(&mut self, i1: usize, i2: usize) {
// we can't just use the pointers returned from `get_address_unchecked_linear_mut` because calling a
// method taking self mutably invalidates any existing (mutable) pointers. since `get_address_unchecked_linear_mut` can
// also be overriden by a custom implementation, we can't just use `wrapping_add` assuming that's what the method does.
// instead, we use `offset_from` to compute the re-calculate the pointers from the base pointer.
// this is sound as long as this trait matches the Validity preconditions
// (and it's the caller's responsibility to ensure the indices are in-bounds).
let base = self.ptr_mut();
let offset1 = self.get_address_unchecked_linear_mut(i1).offset_from(base);
let offset2 = self.get_address_unchecked_linear_mut(i2).offset_from(base);
let base = self.ptr_mut();
let a = base.offset(offset1);
let b = base.offset(offset2);
ptr::swap(a, b);
}
/// Swaps two elements without bound-checking.
///
/// # Safety
/// If the indices are out of bounds, the method will cause undefined behavior.
#[inline]
unsafe fn swap_unchecked(&mut self, row_col1: (usize, usize), row_col2: (usize, usize)) {
let lid1 = self.linear_index(row_col1.0, row_col1.1);
let lid2 = self.linear_index(row_col2.0, row_col2.1);
self.swap_unchecked_linear(lid1, lid2)
}
/// Retrieves the mutable data buffer as a contiguous slice.
///
/// Matrix components may not be contiguous, depending on its strides.
///
/// # Safety
/// The matrix components may not be stored in a contiguous way, depending on the strides.
/// This method is unsafe because this can yield to invalid aliasing when called on some pairs
/// of matrix slices originating from the same matrix with strides.
unsafe fn as_mut_slice_unchecked(&mut self) -> &mut [T];
}
/// Trait shared by all mutable matrix data storage that don’t contain any uninitialized elements.
///
/// # Safety
///
/// See safety note for `Storage`, `RawStorageMut`.
pub unsafe trait StorageMut<T: Scalar, R: Dim, C: Dim = U1>:
Storage<T, R, C> + RawStorageMut<T, R, C>
{
}
unsafe impl<S, T: Scalar, R, C> StorageMut<T, R, C> for S
where
R: Dim,
C: Dim,
S: Storage<T, R, C> + RawStorageMut<T, R, C>,
{
}
/// Marker trait indicating that a storage is stored contiguously in memory.
///
/// # Safety
///
/// The storage requirement means that for any value of `i` in `[0, nrows * ncols - 1]`, the value
/// `.get_unchecked_linear` returns one of the matrix component. This trait is unsafe because
/// failing to comply to this may cause Undefined Behaviors.
pub unsafe trait IsContiguous {}
/// A matrix storage that can be reshaped in-place.
pub trait ReshapableStorage<T, R1, C1, R2, C2>: RawStorage<T, R1, C1>
where
T: Scalar,
R1: Dim,
C1: Dim,
R2: Dim,
C2: Dim,
{
/// The reshaped storage type.
type Output: RawStorage<T, R2, C2>;
/// Reshapes the storage into the output storage type.
fn reshape_generic(self, nrows: R2, ncols: C2) -> Self::Output;
}