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Add equals_layout hook for == on LayoutArrays #284

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Merged
dlfivefifty merged 2 commits into from
Oct 7, 2026
Merged

Add equals_layout hook for == on LayoutArrays #284

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6acafe0
Add equals_layout hook for == on LayoutArrays
dlfivefifty Oct 5, 2026
3f26a0e
Test == with SparseArrays.ReadOnly for coverage
dlfivefifty Oct 7, 2026
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13 changes: 11 additions & 2 deletions ext/ArrayLayoutsSparseArraysExt.jl
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Original file line number Diff line number Diff line change
@@ -1,13 +1,13 @@
module ArrayLayoutsSparseArraysExt

using ArrayLayouts
using ArrayLayouts: copyto!_layout
using ArrayLayouts: copyto!_layout, equals_layout
using SparseArrays
# Specifying the full namespace is necessary because of https://github.com/JuliaLang/julia/issues/48533
# See https://github.com/JuliaStats/LogExpFunctions.jl/pull/63
import ArrayLayouts.LinearAlgebra

import Base: copyto!
import Base: copyto!, ==

# ambiguity from sparsematrix.jl
copyto!(dest::LayoutMatrix, src::SparseArrays.AbstractSparseMatrixCSC) =
Expand All @@ -22,4 +22,13 @@ copyto!(dest::SubArray{<:Any,2,<:LayoutMatrix}, src::SparseArrays.AbstractSparse
@inline LinearAlgebra.dot(a::SparseArrays.SparseVectorUnion{<:Number}, b::LayoutArray{<:Number}) =
ArrayLayouts.dot(a,b)


# ambiguity from SparseArrays.ReadOnly
if isdefined(SparseArrays, :ReadOnly)
==(A::SparseArrays.ReadOnly, B::LayoutVector) = equals_layout(A, B)
==(A::LayoutVector, B::SparseArrays.ReadOnly) = equals_layout(A, B)
==(A::SparseArrays.ReadOnly, B::SubArray{<:Any,1,<:LayoutArray}) = equals_layout(A, B)
==(A::SubArray{<:Any,1,<:LayoutArray}, B::SparseArrays.ReadOnly) = equals_layout(A, B)
end

end
18 changes: 18 additions & 0 deletions src/ArrayLayouts.jl
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Expand Up @@ -309,6 +309,24 @@ mapreduce_layout(::Any, f, op, A, dims; kw...) = invoke(mapreduce, Tuple{Any,Any
Base.mapreduce(f, op, A::LayoutArray; dims=:, kw...) = mapreduce_layout(MemoryLayout(A), f, op, A, dims; kw...)
Base.mapreduce(f, op, A::SubArray{<:Any,N,<:LayoutArray}; dims=:, kw...) where N = mapreduce_layout(MemoryLayout(A), f, op, A, dims; kw...)

"""
equals_layout(layA, layB, A, B)

Layout-aware hook for `A == B`, called with `layA = MemoryLayout(A)` and `layB = MemoryLayout(B)`.
Overload this to specialise equality on memory layouts. The default falls back to the
generic `AbstractArray` implementation in Base.
"""
equals_layout(_, _, A, B) = invoke(==, Tuple{AbstractArray,AbstractArray}, A, B)
equals_layout(A, B) = equals_layout(MemoryLayout(A), MemoryLayout(B), A, B)
==(A::LayoutArray, B::LayoutArray) = equals_layout(A, B)
==(A::LayoutArray, B::AbstractArray) = equals_layout(A, B)
==(A::AbstractArray, B::LayoutArray) = equals_layout(A, B)
==(A::SubArray{<:Any,<:Any,<:LayoutArray}, B::SubArray{<:Any,<:Any,<:LayoutArray}) = equals_layout(A, B)
==(A::SubArray{<:Any,<:Any,<:LayoutArray}, B::LayoutArray) = equals_layout(A, B)
==(A::LayoutArray, B::SubArray{<:Any,<:Any,<:LayoutArray}) = equals_layout(A, B)
==(A::SubArray{<:Any,<:Any,<:LayoutArray}, B::AbstractArray) = equals_layout(A, B)
==(A::AbstractArray, B::SubArray{<:Any,<:Any,<:LayoutArray}) = equals_layout(A, B)


_fill_lmul!(尾, A::AbstractArray) = iszero(尾) ? zero!(A) : lmul!(尾, A)

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39 changes: 39 additions & 0 deletions test/test_layoutarray.jl
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Expand Up @@ -730,6 +730,45 @@ ArrayLayouts.mapreduce_layout(::MyReduceLayout, f, op, A, ::Colon; kw...) = -1.0
@test sum(v; dims=1) == [6.0]
end

struct MyEqualsLayout <: MemoryLayout end
struct MyEqualsVector <: LayoutVector{Float64} end
Base.size(::MyEqualsVector) = (3,)
Base.getindex(::MyEqualsVector, k::Int) = Float64(k)
MemoryLayout(::Type{MyEqualsVector}) = MyEqualsLayout()
ArrayLayouts.equals_layout(::MyEqualsLayout, ::MyEqualsLayout, A, B) = true
ArrayLayouts.equals_layout(::MyEqualsLayout, _, A, B) = false

@testset "==" begin
A = randn(5,4)
M = MyMatrix(A)
@test M == A
@test A == M
@test M == MyMatrix(copy(A))
@test M != MyMatrix(A .+ 1)
@test M != A[:,1:3]
@test view(M, 1:3, 2:4) == A[1:3, 2:4]
@test A[1:3, 2:4] == view(M, 1:3, 2:4)
@test view(M, 1:3, 2:4) == view(MyMatrix(copy(A)), 1:3, 2:4)
@test view(M, 1:3, 2:4) == MyMatrix(A[1:3, 2:4])
@test MyMatrix(A[1:3, 2:4]) == view(M, 1:3, 2:4)
@test view(M, :, 1) != view(M, 1:5, 1:1)
@test MyVector([1.,2,3]) == [1,2,3]

v = MyEqualsVector()
@test v == MyEqualsVector()
@test v != [1.,2,3]
@test [1.,2,3] == v # falls back to generic implementation

if isdefined(SparseArrays, :ReadOnly)
r = SparseArrays.ReadOnly([1.,2,3])
w = MyVector([1.,2,3])
@test r == w
@test w == r
@test r == view(w, :)
@test view(w, :) == r
end
end

@testset "* for infinite layouts" begin
tup = InfSymTridiagonal(), InfTridiagonal(), InfBidiagonal('U'),
InfBidiagonal('L'),
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