nalgebra/src/base/allocator.rs
2020-11-15 16:57:49 +01:00

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//! Abstract definition of a matrix data storage allocator.
use std::any::Any;
use crate::base::constraint::{SameNumberOfColumns, SameNumberOfRows, ShapeConstraint};
use crate::base::dimension::{Dim, U1};
use crate::base::storage::ContiguousStorageMut;
use crate::base::{DefaultAllocator, Scalar};
/// A matrix allocator of a memory buffer that may contain `R::to_usize() * C::to_usize()`
/// elements of type `N`.
///
/// An allocator is said to be:
/// static: if `R` and `C` both implement `DimName`.
/// dynamic: if either one (or both) of `R` or `C` is equal to `Dynamic`.
///
/// Every allocator must be both static and dynamic. Though not all implementations may share the
/// same `Buffer` type.
pub trait Allocator<N: Scalar, R: Dim, C: Dim = U1>: Any + Sized {
/// The type of buffer this allocator can instanciate.
type Buffer: ContiguousStorageMut<N, R, C> + Clone;
/// Allocates a buffer with the given number of rows and columns without initializing its content.
unsafe fn allocate_uninitialized(nrows: R, ncols: C) -> Self::Buffer;
/// Allocates a buffer initialized with the content of the given iterator.
fn allocate_from_iterator<I: IntoIterator<Item = N>>(
nrows: R,
ncols: C,
iter: I,
) -> Self::Buffer;
}
/// A matrix reallocator. Changes the size of the memory buffer that initially contains (RFrom ×
/// CFrom) elements to a smaller or larger size (RTo, CTo).
pub trait Reallocator<N: Scalar, RFrom: Dim, CFrom: Dim, RTo: Dim, CTo: Dim>:
Allocator<N, RFrom, CFrom> + Allocator<N, RTo, CTo>
{
/// Reallocates a buffer of shape `(RTo, CTo)`, possibly reusing a previously allocated buffer
/// `buf`. Data stored by `buf` are linearly copied to the output:
///
/// * The copy is performed as if both were just arrays (without a matrix structure).
/// * If `buf` is larger than the output size, then extra elements of `buf` are truncated.
/// * If `buf` is smaller than the output size, then extra elements of the output are left
/// uninitialized.
unsafe fn reallocate_copy(
nrows: RTo,
ncols: CTo,
buf: <Self as Allocator<N, RFrom, CFrom>>::Buffer,
) -> <Self as Allocator<N, RTo, CTo>>::Buffer;
}
/// The number of rows of the result of a componentwise operation on two matrices.
pub type SameShapeR<R1, R2> = <ShapeConstraint as SameNumberOfRows<R1, R2>>::Representative;
/// The number of columns of the result of a componentwise operation on two matrices.
pub type SameShapeC<C1, C2> = <ShapeConstraint as SameNumberOfColumns<C1, C2>>::Representative;
// TODO: Bad name.
/// Restricts the given number of rows and columns to be respectively the same.
pub trait SameShapeAllocator<N, R1, C1, R2, C2>:
Allocator<N, R1, C1> + Allocator<N, SameShapeR<R1, R2>, SameShapeC<C1, C2>>
where
R1: Dim,
R2: Dim,
C1: Dim,
C2: Dim,
N: Scalar,
ShapeConstraint: SameNumberOfRows<R1, R2> + SameNumberOfColumns<C1, C2>,
{
}
impl<N, R1, R2, C1, C2> SameShapeAllocator<N, R1, C1, R2, C2> for DefaultAllocator
where
R1: Dim,
R2: Dim,
C1: Dim,
C2: Dim,
N: Scalar,
DefaultAllocator: Allocator<N, R1, C1> + Allocator<N, SameShapeR<R1, R2>, SameShapeC<C1, C2>>,
ShapeConstraint: SameNumberOfRows<R1, R2> + SameNumberOfColumns<C1, C2>,
{
}
// XXX: Bad name.
/// Restricts the given number of rows to be equal.
pub trait SameShapeVectorAllocator<N, R1, R2>:
Allocator<N, R1> + Allocator<N, SameShapeR<R1, R2>> + SameShapeAllocator<N, R1, U1, R2, U1>
where
R1: Dim,
R2: Dim,
N: Scalar,
ShapeConstraint: SameNumberOfRows<R1, R2>,
{
}
impl<N, R1, R2> SameShapeVectorAllocator<N, R1, R2> for DefaultAllocator
where
R1: Dim,
R2: Dim,
N: Scalar,
DefaultAllocator: Allocator<N, R1, U1> + Allocator<N, SameShapeR<R1, R2>>,
ShapeConstraint: SameNumberOfRows<R1, R2>,
{
}