nalgebra/src/base/storage.rs

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//! Abstract definition of a matrix data storage.
use std::fmt::Debug;
use std::mem;
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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)`.
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pub type SameShapeStorage<N, R1, C1, R2, C2> =
<DefaultAllocator as Allocator<N, SameShapeR<R1, R2>, SameShapeC<C1, C2>>>::Buffer;
// FIXME: better name than Owned ?
/// The owned data storage that can be allocated from `S`.
pub type Owned<N, R, C = U1> = <DefaultAllocator as Allocator<N, R, C>>::Buffer;
/// The row-stride of the owned data storage for a buffer of dimension `(R, C)`.
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pub type RStride<N, R, C = U1> =
<<DefaultAllocator as Allocator<N, R, C>>::Buffer as Storage<N, R, C>>::RStride;
/// The column-stride of the owned data storage for a buffer of dimension `(R, C)`.
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pub type CStride<N, R, C = U1> =
<<DefaultAllocator as Allocator<N, R, C>>::Buffer as Storage<N, R, C>>::CStride;
/// The trait shared by all matrix data storage.
///
/// FIXME: doc
///
/// 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<N: Scalar, R: Dim, C: Dim = U1>: Debug + 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 N;
/// 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);
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/// The spacing between consecutive row elements and consecutive column elements.
///
/// For example this returns `(1, 5)` for a row-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.
#[inline]
unsafe fn get_address_unchecked_linear(&self, i: usize) -> *const N {
let shape = self.shape();
if shape.0.value() * shape.1.value() == 0 {
// If we have a zero-size matrix, our pointer must
// be dangling. Instead of calling 'offset', we
// just re-use our pointer, since actually using
// it would be undefined behavior
self.ptr()
} else {
self.ptr().offset(i as isize)
}
}
/// Gets the address of the i-th matrix component without performing bound-checking.
#[inline]
unsafe fn get_address_unchecked(&self, irow: usize, icol: usize) -> *const N {
self.get_address_unchecked_linear(self.linear_index(irow, icol))
}
/// Retrieves a reference to the i-th element without bound-checking.
#[inline]
unsafe fn get_unchecked_linear(&self, i: usize) -> &N {
&*self.get_address_unchecked_linear(i)
}
/// Retrieves a reference to the i-th element without bound-checking.
#[inline]
unsafe fn get_unchecked(&self, irow: usize, icol: usize) -> &N {
self.get_unchecked_linear(self.linear_index(irow, icol))
}
/// Indicates whether this data buffer stores its elements contiguously.
#[inline]
fn is_contiguous(&self) -> bool;
/// Retrieves the data buffer as a contiguous slice.
///
/// The matrix components may not be stored in a contiguous way, depending on the strides.
#[inline]
fn as_slice(&self) -> &[N];
/// Builds a matrix data storage that does not contain any reference.
fn into_owned(self) -> Owned<N, R, C>
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where DefaultAllocator: Allocator<N, R, C>;
/// Clones this data storage to one that does not contain any reference.
fn clone_owned(&self) -> Owned<N, R, C>
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where DefaultAllocator: Allocator<N, R, C>;
}
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/// Trait implemented by matrix data storage that can provide a mutable access to its elements.
///
/// Note that a mutable access does not mean that the matrix owns its data. For example, a mutable
/// matrix slice 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 StorageMut<N: Scalar, R: Dim, C: Dim = U1>: Storage<N, R, C> {
/// The matrix mutable data pointer.
fn ptr_mut(&mut self) -> *mut N;
/// Gets the mutable address of the i-th matrix component without performing bound-checking.
#[inline]
unsafe fn get_address_unchecked_linear_mut(&mut self, i: usize) -> *mut N {
let shape = self.shape();
if shape.0.value() * shape.1.value() == 0 {
// If we have a zero-size matrix, our pointer must
// be dangling. Instead of calling 'offset', we
// just re-use our pointer, since actually using
// it would be undefined behavior
self.ptr_mut()
} else {
self.ptr_mut().offset(i as isize)
}
}
/// Gets the mutable address of the i-th matrix component without performing bound-checking.
#[inline]
unsafe fn get_address_unchecked_mut(&mut self, irow: usize, icol: usize) -> *mut N {
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.
unsafe fn get_unchecked_linear_mut(&mut self, i: usize) -> &mut N {
&mut *self.get_address_unchecked_linear_mut(i)
}
/// Retrieves a mutable reference to the element at `(irow, icol)` without bound-checking.
#[inline]
unsafe fn get_unchecked_mut(&mut self, irow: usize, icol: usize) -> &mut N {
&mut *self.get_address_unchecked_mut(irow, icol)
}
/// Swaps two elements using their linear index without bound-checking.
#[inline]
unsafe fn swap_unchecked_linear(&mut self, i1: usize, i2: usize) {
let a = self.get_address_unchecked_linear_mut(i1);
let b = self.get_address_unchecked_linear_mut(i2);
mem::swap(&mut *a, &mut *b);
}
/// Swaps two elements without bound-checking.
#[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.
#[inline]
fn as_mut_slice(&mut self) -> &mut [N];
}
/// A matrix storage that is stored contiguously in memory.
///
/// The storage requirement means that for any value of `i` in `[0, nrows * ncols[`, 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.
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pub unsafe trait ContiguousStorage<N: Scalar, R: Dim, C: Dim = U1>:
Storage<N, R, C>
{
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}
/// A mutable matrix storage that is stored contiguously in memory.
///
/// The storage requirement means that for any value of `i` in `[0, nrows * ncols[`, 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.
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pub unsafe trait ContiguousStorageMut<N: Scalar, R: Dim, C: Dim = U1>:
ContiguousStorage<N, R, C> + StorageMut<N, R, C>
{
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}