Support Diagonal(::AbstractBlockVector) (#151)

* Support Diagonal(::AbstractBlockVector)

* Update blockarrayinterface.jl

* fix tests

* Update test_blockarrayinterface.jl

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "BlockArrays"
 uuid = "8e7c35d0-a365-5155-bbbb-fb81a777f24e"
-version = "0.14.1"
+version = "0.14.2"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/BlockArrays.jl

@@ -48,13 +48,14 @@ include("blockarray.jl")
 include("pseudo_blockarray.jl")
 include("views.jl")
 include("blocks.jl")
-include("blockarrayinterface.jl")
+
 include("blockbroadcast.jl")
 include("blocklinalg.jl")
 include("blockproduct.jl")
 include("show.jl")
 include("blockreduce.jl")
 include("blockdeque.jl")
+include("blockarrayinterface.jl")
 
 @deprecate getblock(A::AbstractBlockArray{T,N}, I::Vararg{Integer, N}) where {T,N} view(A, Block(I))
 @deprecate getblock!(X, A::AbstractBlockArray{T,N}, I::Vararg{Integer, N}) where {T,N} copyto!(X, view(A, Block(I)))

src/blockarrayinterface.jl

@@ -11,6 +11,11 @@ axes(A::HermOrSym{<:Any,<:AbstractBlockMatrix}) = _sym_axes(A)
 axes(A::HermOrSym{<:Any,<:SubArray{<:Any,2,<:AbstractBlockMatrix}}) = _sym_axes(A)
 axes(A::AbstractTriangular{<:Any,<:AbstractBlockMatrix}) = axes(parent(A))
 axes(A::AbstractTriangular{<:Any,<:SubArray{<:Any,2,<:AbstractBlockMatrix}}) = axes(parent(A))
+function axes(D::Diagonal{<:Any,<:AbstractBlockVector})
+    a = axes(parent(D),1)
+    (a,a)
+end
+ArrayLayouts.diagonallayout(lay::AbstractBlockLayout) = DiagonalLayout{typeof(lay)}()
 
 blocksize(A::AbstractTriangular) = blocksize(parent(A))
 blocksize(A::AbstractTriangular, i::Int) = blocksize(parent(A), i)

test/test_blockarrayinterface.jl

@@ -1,5 +1,6 @@
 using BlockArrays, LinearAlgebra, FillArrays, Base64, Test
 
+# avoid fast-paths for view
 bview(a, b) = Base.invoke(view, Tuple{AbstractArray,Any}, a, b)
 
 @testset "Array block interface" begin
@@ -103,6 +104,13 @@ end
     @test A[Block(1,2)] == [0 0]
     @test_throws BlockBoundsError A[Block(1,3)]
     @test A == [1 2 0 0; 0 0 1 2]
+
+    N = 3
+    D = Diagonal(mortar(Fill.(-(0:N)-(0:N).^2, 1:2:2N+1)))
+    @test axes(D) isa NTuple{2,BlockedUnitRange}
+    @test blockisequal(axes(D,1), axes(parent(D),1))
+    @test D == Diagonal(Vector(parent(D)))
+    @test MemoryLayout(D) isa BlockArrays.DiagonalLayout{<:BlockArrays.BlockLayout}
 end
 
 @testset "non-standard block axes" begin