Make extension depend on StaticArrays and optimize lu_instance

Project.toml

@@ -15,7 +15,7 @@ ChainRules = "082447d4-558c-5d27-93f4-14fc19e9eca2"
 GPUArraysCore = "46192b85-c4d5-4398-a991-12ede77f4527"
 ReverseDiff = "37e2e3b7-166d-5795-8a7a-e32c996b4267"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
-StaticArraysCore = "1e83bf80-4336-4d27-bf5d-d5a4f845583c"
+StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
 Tracker = "9f7883ad-71c0-57eb-9f7f-b5c9e6d3789c"
 
 [extensions]
@@ -27,7 +27,7 @@ ArrayInterfaceChainRulesExt = "ChainRules"
 ArrayInterfaceGPUArraysCoreExt = "GPUArraysCore"
 ArrayInterfaceReverseDiffExt = "ReverseDiff"
 ArrayInterfaceSparseArraysExt = "SparseArrays"
-ArrayInterfaceStaticArraysCoreExt = "StaticArraysCore"
+ArrayInterfaceStaticArraysExt = "StaticArrays"
 ArrayInterfaceTrackerExt = "Tracker"
 
 [compat]
@@ -66,4 +66,4 @@ Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 Tracker = "9f7883ad-71c0-57eb-9f7f-b5c9e6d3789c"
 
 [targets]
-test = ["SafeTestsets", "Pkg", "Test", "Aqua", "Random", "SparseArrays", "SuiteSparse", "BandedMatrices", "BlockBandedMatrices", "GPUArraysCore", "StaticArrays", "StaticArraysCore", "Tracker", "ReverseDiff", "ChainRules", "FillArrays", "ComponentArrays"]
+test = ["SafeTestsets", "Pkg", "Test", "Aqua", "Random", "SparseArrays", "SuiteSparse", "BandedMatrices", "BlockBandedMatrices", "GPUArraysCore", "StaticArrays", "Tracker", "ReverseDiff", "ChainRules", "FillArrays", "ComponentArrays"]

ext/ArrayInterfaceStaticArraysExt.jl

@@ -0,0 +1,34 @@
+module ArrayInterfaceStaticArraysExt
+
+import ArrayInterface
+using LinearAlgebra
+import StaticArrays: SArray, SMatrix, SVector, StaticMatrix, StaticArray, SizedArray, MArray, MMatrix, LU
+
+function ArrayInterface.undefmatrix(::MArray{S, T, N, L}) where {S, T, N, L}
+    return MMatrix{L, L, T, L*L}(undef)
+end
+# SArray doesn't have an undef constructor and is going to be small enough that this is fine.
+function ArrayInterface.undefmatrix(s::SArray)
+    v = vec(s)
+    return v.*v'
+end
+
+ArrayInterface.ismutable(::Type{<:StaticArray}) = false
+ArrayInterface.ismutable(::Type{<:MArray}) = true
+ArrayInterface.ismutable(::Type{<:SizedArray}) = true
+
+ArrayInterface.can_setindex(::Type{<:StaticArray}) = false
+ArrayInterface.can_setindex(::Type{<:MArray}) = true
+ArrayInterface.buffer(A::Union{SArray, MArray}) = getfield(A, :data)
+
+function ArrayInterface.lu_instance(A::SMatrix{N,N}) where {N}
+    LU(LowerTriangular(A), UpperTriangular(A), SVector{N}(1:N))
+end
+
+function ArrayInterface.lu_instance(A::StaticMatrix{N,N}) where {N}
+    lu(one(A))
+end
+
+ArrayInterface.restructure(x::SArray{S}, y) where {S} = SArray{S}(y)
+
+end

test/runtests.jl

@@ -14,7 +14,7 @@ end
         @time @safetestset "BlockBandedMatrices" begin include("blockbandedmatrices.jl") end
         @time @safetestset "Core" begin include("core.jl") end
         @time @safetestset "AD Integration" begin include("ad.jl") end
-        @time @safetestset "StaticArraysCore" begin include("staticarrayscore.jl") end
+        @time @safetestset "StaticArrays" begin include("staticarrays.jl") end
         @time @safetestset "ChainRules" begin include("chainrules.jl") end
     end