Forward reduced_indices to parent (#297)

* forward reduced_indices to parent

* Add test for standard arrays

* remove explicit test against StaticArrays

Author: jishnub

Project.toml

@@ -1,6 +1,6 @@
 name = "OffsetArrays"
 uuid = "6fe1bfb0-de20-5000-8ca7-80f57d26f881"
-version = "1.12.4"
+version = "1.12.5"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
@@ -12,7 +12,7 @@ CatIndices = "0.2"
 DistributedArrays = "0.6"
 Documenter = "0.27"
 EllipsisNotation = "1"
-FillArrays = "0.11"
+FillArrays = "0.11, 0.13"
 StaticArrays = "1"
 julia = "0.7, 1"
 

src/axes.jl

@@ -175,6 +175,16 @@ offset_coerce(::Type{I}, r::AbstractUnitRange) where I<:AbstractUnitRange =
 @inline Base.unsafe_indices(r::IdOffsetRange) = (Base.axes1(r),)
 @inline Base.length(r::IdOffsetRange) = length(r.parent)
 @inline Base.isempty(r::IdOffsetRange) = isempty(r.parent)
+#= We specialize on reduced_indices to work around cases where the parent axis type doesn't
+support reduced_index, but the axes do support reduced_indices
+The difference is that reduced_index expects the axis type to remain unchanged,
+which may not always be possible, eg. for statically sized axes
+See https://github.com/JuliaArrays/OffsetArrays.jl/issues/204
+=#
+function Base.reduced_indices(inds::Tuple{IdOffsetRange, Vararg{IdOffsetRange}}, d::Int)
+    parents_reduced = Base.reduced_indices(map(parent, inds), d)
+    ntuple(i -> IdOffsetRange(parents_reduced[i], inds[i].offset), Val(length(inds)))
+end
 Base.reduced_index(i::IdOffsetRange) = typeof(i)(first(i):first(i))
 # Workaround for #92 on Julia < 1.4
 Base.reduced_index(i::IdentityUnitRange{<:IdOffsetRange}) = typeof(i)(first(i):first(i))

test/Project.toml

@@ -18,5 +18,5 @@ CatIndices = "0.2"
 DistributedArrays = "0.6"
 Documenter = "0.27"
 EllipsisNotation = "1"
-FillArrays = "0.11"
+FillArrays = "0.11, 0.13"
 StaticArrays = "1"

test/runtests.jl

@@ -234,6 +234,17 @@ end
     @test length(rred) == 1
     @test first(rred) == first(r)
 
+    @testset "reduced_indices" begin
+        a = reshape(1:24, 2, 3, 4)
+        sa = OffsetArray(a, (2, 3, 4));
+        @testset for dim in 1:ndims(sa)
+            sasum = sum(sa, dims = dim)
+            @test parent(sasum) == sum(a, dims = dim)
+            find = firstindex(sa, dim)
+            @test axes(sasum, dim) == find:find
+        end
+    end
+
     @testset "conversion to AbstractUnitRange" begin
         r = IdOffsetRange(1:2)
         @test AbstractUnitRange{Int}(r) === r