Fix iteration for 0-dimensional disk arrays (#293)

* test: Add breaking iter test for 0-dim arrays

* fix: Fix iteration for 0-dim arrays

* chore: Increment patch number

* fix: Model iteration on method for Arrays

* fix: remove Tuple type param from chunked _iterate_disk to resolve ambiguity

* chore: Increment patch number

* Update src/iterator.jl

Co-authored-by: Anshul Singhvi <anshulsinghvi@gmail.com>

---------

Co-authored-by: Anshul Singhvi <anshulsinghvi@gmail.com>

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 = "0.4.21"
+version = "0.4.22"
 
 [deps]
 ConstructionBase = "187b0558-2788-49d3-abe0-74a17ed4e7c9"

src/iterator.jl

@@ -61,11 +61,9 @@ end
 # Implementaion macros
 
 # Nested iteration over chunks
-@noinline function _iterate_disk(
-    a::AbstractArray{T}, i::I
-) where {T,I<:Tuple{A,B,C}} where {A,B,C}
+@noinline function _iterate_disk(a::AbstractArray{T}, i::I) where {T, I}
     # Split the data, block indices and state from the iterator
-    currentdata::A, blockinds::B, state::C = i
+    currentdata, blockinds, state = i
     # And split the block stat into the chunk iterator and inner indices
     (chunkstate, innerstate) = state
     # Need to check now as state will be updated
@@ -84,13 +82,15 @@ end
             newchunk = newinnerstate.itr.indices
             # Get a new chunk of data
             newdata = OffsetArray(a[newchunk...], newinnerstate.itr)
-            return newdata[i]::T, (newdata, blockinds, newstate)::I
+            return newdata[i]::T, (newdata, blockinds, newstate)
         else
             # Current chunk still has values left to iterate over
-            return currentdata[i]::T, (currentdata, blockinds, newstate)::I
+            return currentdata[i]::T, (currentdata, blockinds, newstate)
         end
     end
 end
+_iterate_disk(a::AbstractArray{<:Any,0}, i=1) = i == 1 ? (@inbounds a[i], 2) : nothing
+
 @noinline function _iterate_disk(a)
     # Get the indices for each chunk of data
     blockinds = BlockedIndices(eachchunk(a))

test/runtests.jl

@@ -387,6 +387,15 @@ end
     end
 end
 
+# https://github.com/JuliaIO/DiskArrays.jl/issues/289
+@testset "iteration works for 0-dimensional arrays" begin
+    a = UnchunkedDiskArray(fill(42))
+    @test iterate(a) == (42, 2)
+    @test iterate(a, 1) == (42, 2)
+    @test iterate(a, 2) === nothing
+    @test collect(a) == fill(42)
+end
+
 @testset "Views" begin
     a = AccessCountDiskArray(zeros(Int, 4, 5, 1))
     test_view(a)