Negate RangeCumSum (#215)

Author: jishnub

src/cumsum.jl

@@ -41,6 +41,9 @@ 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(-), r::RangeCumsum)
+    RangeCumsum(.-r.range)
+end
 function Broadcast.broadcasted(::Broadcast.DefaultArrayStyle{1}, ::typeof(*), x::Number, r::RangeCumsum)
     RangeCumsum(x * r.range)
 end

test/test_cumsum.jl

@@ -10,13 +10,14 @@ include("infinitearrays.jl")
         r = RangeCumsum(p)
         @test parent(r) == p
         @test r == r
-        if axes(r) isa Base.OneTo
+        if axes(r,1) isa Base.OneTo
             @test r == cumsum(p)
             @test r .+ 1 == cumsum(p) .+ 1
             @test r[Base.OneTo(3)] == r[1:3]
             @test @view(r[Base.OneTo(3)]) === r[Base.OneTo(3)] == r[1:3]
             @test @view(r[Base.OneTo(3)]) isa RangeCumsum
             @test diff(r) == diff(Vector(r))
+            @test -r == -Vector(r)
         end
         @test diff(r) == p[firstindex(p)+1:end]
         @test last(r) == r[end] == sum(p)