Fixed infinite indexing with cumsum (#173)

* Fixed infinite indexing with cumsum

* Update Project.toml

* Update Project.toml

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "InfiniteArrays"
 uuid = "4858937d-0d70-526a-a4dd-2d5cb5dd786c"
-version = "0.13.7"
+version = "0.13.8"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
@@ -11,18 +11,10 @@ LazyArrays = "5078a376-72f3-5289-bfd5-ec5146d43c02"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
-[weakdeps]
-DSP = "717857b8-e6f2-59f4-9121-6e50c889abd2"
-Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
-
-[extensions]
-InfiniteArraysDSPExt = "DSP"
-InfiniteArraysStatisticsExt = "Statistics"
-
 [compat]
 Aqua = "0.8"
-ArrayLayouts = "1.0"
-BandedMatrices = "0.17.18, 1"
+ArrayLayouts = "1.8"
+BandedMatrices = "0.17.18, 1.0"
 Base64 = "1"
 DSP = "0.7"
 FillArrays = "1.0"
@@ -35,6 +27,10 @@ Statistics = "1"
 Test = "1"
 julia = "1.6"
 
+[extensions]
+InfiniteArraysDSPExt = "DSP"
+InfiniteArraysStatisticsExt = "Statistics"
+
 [extras]
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
 BandedMatrices = "aae01518-5342-5314-be14-df237901396f"
@@ -47,3 +43,7 @@ Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
 test = ["Aqua", "Test", "BandedMatrices", "LazyBandedMatrices", "Statistics", "SparseArrays", "Base64", "DSP"]
+
+[weakdeps]
+DSP = "717857b8-e6f2-59f4-9121-6e50c889abd2"
+Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"

src/infrange.jl

@@ -513,7 +513,10 @@ cumsum(r::InfRanges) = RangeCumsum(r)
 diff(r::InfRanges) = Fill(step(r),∞)
 diff(r::AbstractInfUnitRange{T}) where T = Ones{T}(∞)
 Base.@propagate_inbounds getindex(c::RangeCumsum, kr::OneToInf) = RangeCumsum(c.range[kr])
-getindex(c::RangeCumsum{<:Any,<:OneToInf}, k::Integer) = k * (k+1) ÷ 2
+Base.@propagate_inbounds function getindex(c::RangeCumsum{<:Any,<:OneToInf}, k::Integer)
+    @boundscheck checkbounds(c, k)
+    k * (k+1) ÷ 2
+end
 function union(r1::RangeCumsum{T1, OneToInf{T1}}, r2::RangeCumsum{T2, OneToInf{T2}}) where {T1,T2}
     T = promote_type(T1, T2)
     RangeCumsum(OneToInf{T}())
@@ -522,6 +525,12 @@ Base.issorted(r::RangeCumsum{<:Any,<:OneToInf}) = true
 Base.sort(r::RangeCumsum{<:Any,<:OneToInf}) = r
 Base.sort!(r::RangeCumsum{<:Any,<:OneToInf}) = r
 
+getindex(c::RangeCumsum{<:Any,<:OneToInf}, ::InfiniteCardinal{0}) = last(c)
+Base.@propagate_inbounds function getindex(c::RangeCumsum{<:Any,<:AbstractRange}, k::InfiniteCardinal{0})
+    @boundscheck checkbounds(c, k)
+    last(c)
+end
+Base._unsafe_getindex(::IndexStyle, A::RangeCumsum, I::InfiniteCardinal{0}) = last(A)
 # vcat
 
 vcat(a::Number, r::InfRanges) = Vcat(a, r)

test/runtests.jl

@@ -226,6 +226,7 @@ end
             rs = cumsum(r)
             @test sort(rs) === sort!(rs) === rs
             @test @inferred((rs -> Val(issorted(rs)))(rs)) isa Val{true}
+            @test rs[end] ≡ ℵ₀
         end
     end
     @testset "in" begin
@@ -945,6 +946,11 @@ end
         @test exp.(c)[1:20] == exp.(c[1:20])
     end
 
+    @test cumsum(3:4:∞)[end] ≡ cumsum(3:4:∞)[∞] ≡ cumsum(3:4:∞)[ℵ₀] ≡ RealInfinity()
+    @test cumsum(2:∞)[end] ≡ cumsum(2:∞)[∞] ≡ cumsum(2:∞)[ℵ₀] ≡ cumsum(oneto(∞))[end] ≡ cumsum(oneto(∞))[∞] ≡ cumsum(oneto(∞))[ℵ₀] ≡  ℵ₀
+
+    @test_throws BoundsError cumsum(oneto(∞))[-5]
+
     @test cumsum(1:∞)[2:∞][1:5] == cumsum(1:6)[2:end]
 
     @testset "union of cumsum" begin