forked from M-Labs/nalgebra
92 lines
2.7 KiB
Rust
92 lines
2.7 KiB
Rust
//! Compatibility constraints between matrix shapes, e.g., for addition or multiplication.
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use crate::base::dimension::{Dim, DimName, Dyn};
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/// A type used in `where` clauses for enforcing constraints.
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#[derive(Copy, Clone, Debug)]
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pub struct ShapeConstraint;
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/// Constrains `C1` and `R2` to be equivalent.
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pub trait AreMultipliable<R1: Dim, C1: Dim, R2: Dim, C2: Dim>: DimEq<C1, R2> {}
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impl<R1: Dim, C1: Dim, R2: Dim, C2: Dim> AreMultipliable<R1, C1, R2, C2> for ShapeConstraint where
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ShapeConstraint: DimEq<C1, R2>
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{
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}
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/// Constrains `D1` and `D2` to be equivalent.
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pub trait DimEq<D1: Dim, D2: Dim> {
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/// This is either equal to `D1` or `D2`, always choosing the one (if any) which is a type-level
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/// constant.
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type Representative: Dim;
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}
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impl<D: Dim> DimEq<D, D> for ShapeConstraint {
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type Representative = D;
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}
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impl<D: DimName> DimEq<D, Dyn> for ShapeConstraint {
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type Representative = D;
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}
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impl<D: DimName> DimEq<Dyn, D> for ShapeConstraint {
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type Representative = D;
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}
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macro_rules! equality_trait_decl(
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($($doc: expr, $Trait: ident),* $(,)*) => {$(
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// XXX: we can't do something like `DimEq<D1> for D2` because we would require a blanket impl…
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#[doc = $doc]
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pub trait $Trait<D1: Dim, D2: Dim>: DimEq<D1, D2> + DimEq<D2, D1> {
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/// This is either equal to `D1` or `D2`, always choosing the one (if any) which is a type-level
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/// constant.
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type Representative: Dim;
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}
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impl<D: Dim> $Trait<D, D> for ShapeConstraint {
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type Representative = D;
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}
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impl<D: DimName> $Trait<D, Dyn> for ShapeConstraint {
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type Representative = D;
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}
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impl<D: DimName> $Trait<Dyn, D> for ShapeConstraint {
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type Representative = D;
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}
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)*}
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);
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equality_trait_decl!(
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"Constrains `D1` and `D2` to be equivalent. \
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They are both assumed to be the number of \
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rows of a matrix.",
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SameNumberOfRows,
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"Constrains `D1` and `D2` to be equivalent. \
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They are both assumed to be the number of \
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columns of a matrix.",
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SameNumberOfColumns
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);
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/// Constrains D1 and D2 to be equivalent, where they both designate dimensions of algebraic
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/// entities (e.g. square matrices).
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pub trait SameDimension<D1: Dim, D2: Dim>:
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SameNumberOfRows<D1, D2> + SameNumberOfColumns<D1, D2>
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{
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/// This is either equal to `D1` or `D2`, always choosing the one (if any) which is a type-level
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/// constant.
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type Representative: Dim;
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}
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impl<D: Dim> SameDimension<D, D> for ShapeConstraint {
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type Representative = D;
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}
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impl<D: DimName> SameDimension<D, Dyn> for ShapeConstraint {
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type Representative = D;
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}
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impl<D: DimName> SameDimension<Dyn, D> for ShapeConstraint {
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type Representative = D;
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}
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