Implement similar and copy for 0-dimensional arrays (#286)

* Add failing test

* Add similar overloads for zero-dimensional broadcast

* Add copy overloads for zero-dimensional broadcast

* Increment patch number

* Generalize test to support bool

* Make sure test covers both cases

Author: sethaxen

Project.toml

@@ -1,7 +1,7 @@
 name = "DiskArrays"
 uuid = "3c3547ce-8d99-4f5e-a174-61eb10b00ae3"
 authors = ["Fabian Gans <fgans@bgc-jena.mpg.de>"]
-version = "0.4.18"
+version = "0.4.19"
 
 [deps]
 ConstructionBase = "187b0558-2788-49d3-abe0-74a17ed4e7c9"

src/broadcast.jl

@@ -28,6 +28,7 @@ Base.copy(a::BroadcastDiskArray) = copyto!(zeros(eltype(a), size(a)), a.broadcas
 
 Base.copy(broadcasted::Broadcasted{ChunkStyle{N}}) where {N} =
     BroadcastDiskArray(flatten(broadcasted))
+@inline Base.copy(broadcasted::Broadcasted{ChunkStyle{0}}) = broadcasted[CartesianIndex()]
 function Base.copyto!(dest::AbstractArray, broadcasted::Broadcasted{ChunkStyle{N}}) where {N}
     bcf = flatten(broadcasted)
     # Get a list of chunks to apply
@@ -42,6 +43,13 @@ function Base.copyto!(dest::AbstractArray, broadcasted::Broadcasted{ChunkStyle{N
     return dest
 end
 
+function Base.similar(::Broadcasted{ChunkStyle{0}}, ::Type{ElType}, dims) where {ElType}
+    return similar(Array{ElType, length(dims)}, dims)
+end
+function Base.similar(::Broadcasted{ChunkStyle{0}}, ::Type{Bool}, dims)
+    return similar(BitArray, dims)
+end
+
 # DiskArrays interface
 
 haschunks(a::BroadcastDiskArray) = Chunked()

test/runtests.jl

@@ -357,6 +357,28 @@ end
     @test a[] == 6
 end
 
+# https://github.com/JuliaIO/DiskArrays.jl/issues/285
+@testset "basic array ops work for 0-dimensional arrays" begin
+    @testset "Int" begin
+        aval, bval = 2, 3
+        a = UnchunkedDiskArray(fill(aval))
+        b = UnchunkedDiskArray(fill(bval))
+        @testset for op in (-, +)
+            cval = op(aval, bval)
+            c = @inferred op(a, b)
+            @test c isa Array{typeof(cval),0}
+            @test c[] == cval
+        end
+    end
+    @testset "Bool" begin
+        a = UnchunkedDiskArray(fill(true))
+        cval = true * false
+        c = @inferred a * false
+        @test c isa BitArray{0}
+        @test c[] == cval
+    end
+end
+
 @testset "Views" begin
     a = AccessCountDiskArray(zeros(Int, 4, 5, 1))
     test_view(a)