Multiply RangeCumSum by a number (#211)

* Multiply RangeCumSum by a number

* Add tests for both orderings

* Test for types

Author: jishnub

Diff for: Project.toml

@@ -1,7 +1,7 @@
 name = "ArrayLayouts"
 uuid = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
 authors = ["Sheehan Olver <[email protected]>"]
-version = "1.6.2"
+version = "1.7.0"
 
 [deps]
 FillArrays = "1a297f60-69ca-5386-bcde-b61e274b549b"

Diff for: src/cumsum.jl

@@ -38,3 +38,10 @@ sort!(a::RangeCumsum{<:Any,<:Base.OneTo}) = a
 sort(a::RangeCumsum{<:Any,<:Base.OneTo}) = a
 
 convert(::Type{RangeCumsum{T,R}}, r::RangeCumsum) where {T,R} = RangeCumsum{T,R}(convert(R, r.range))
+
+function Broadcast.broadcasted(::Broadcast.DefaultArrayStyle{1}, ::typeof(*), x::Number, r::RangeCumsum)
+    RangeCumsum(x * r.range)
+end
+function Broadcast.broadcasted(::Broadcast.DefaultArrayStyle{1}, ::typeof(*), r::RangeCumsum, x::Number)
+    RangeCumsum(r.range * x)
+end

Diff for: test/test_cumsum.jl

@@ -37,6 +37,22 @@ include("infinitearrays.jl")
 
     r = RangeCumsum(InfiniteArrays.OneToInf())
     @test axes(r, 1) == InfiniteArrays.OneToInf()
+
+    @testset "multiplication by a number" begin
+        function test_broadcast(n, r)
+            w = Vector(r)
+            @test n * r isa RangeCumsum
+            @test n * r ≈ n * w
+            @test r * n isa RangeCumsum
+            @test r * n ≈ w * n
+        end
+        for p in (Base.OneTo(4), -4:4, -4:2:4, -1.0:3.0:5.0)
+            r = RangeCumsum(p)
+            test_broadcast(3, r)
+            test_broadcast(3.5, r)
+            test_broadcast(3.5 + 2im, r)
+        end
+    end
 end
 
 end