Make CartesianRange an AbstractArray

Author: barche

base/multidimensional.jl

@@ -185,7 +185,7 @@ module IteratorsMD
     CartesianIndex(2, 2, 2)
     ```
     """
-    struct CartesianRange{N,R<:NTuple{N,AbstractUnitRange{Int}}}
+    struct CartesianRange{N,R<:NTuple{N,AbstractUnitRange{Int}}} <: AbstractArray{CartesianIndex{N},N}
         indices::R
     end
 
@@ -222,6 +222,10 @@ module IteratorsMD
     convert(::Type{Tuple{Vararg{UnitRange}}}, R::CartesianRange) =
         convert(Tuple{Vararg{UnitRange{Int}}}, R)
 
+    # AbstractArray implementation
+    Base.IndexStyle(::Type{CartesianRange{N,R}}) where {N,R} = IndexCartesian()
+    @inline Base.getindex(iter::CartesianRange{N,R}, I::Vararg{Int, N}) where {N,R} = CartesianIndex(first.(iter.indices) .- 1) + CartesianIndex(I)
+
     ndims(R::CartesianRange) = ndims(typeof(R))
     ndims(::Type{CartesianRange{N}}) where {N} = N
     ndims(::Type{CartesianRange{N,TT}}) where {N,TT} = N

test/abstractarray.jl

@@ -877,3 +877,21 @@ end
     Z = Array{Int}(); Z[] = 17
     @test Z == collect(Z) == copy(Z)
 end
+
+@testset "CartesianRange" begin
+    xrng = 2:4
+    yrng = 1:5
+    CR = CartesianRange((xrng,yrng))
+
+    for (i,i_idx) in enumerate(xrng)
+        for (j,j_idx) in enumerate(yrng)
+            @test CR[i,j] == CartesianIndex(i_idx,j_idx)
+        end
+    end
+
+    for i_lin in linearindices(CR)
+        i = (i_lin-1) % length(xrng) + 1
+        j = (i_lin-i) ÷ length(xrng) + 1
+        @test CR[i_lin] == CartesianIndex(xrng[i],yrng[j])
+    end
+end