IteratorSize for infinite ranges (#105)

* IteratorSize for infinite ranges

* Add tests

* restore deleted line

* version bump to v0.12.9

* InfAxes -> InfRanges

Author: jishnub

src/infrange.jl

@@ -89,6 +89,8 @@ AbstractVector{T}(a::InfStepRange) where T<:Real = InfStepRange(convert(T,a.star
 const InfRanges{T} = Union{InfStepRange{T},AbstractInfUnitRange{T}}
 const InfAxes = Union{InfRanges{<:Integer},Slice{<:AbstractInfUnitRange{<:Integer}},IdentityUnitRange{<:AbstractInfUnitRange{<:Integer}}}
 
+Base.IteratorSize(::Type{<:InfRanges}) = Base.IsInfinite()
+
 AbstractArray{T}(ac::Adjoint{<:Any,<:InfRanges}) where T<:Real = AbstractArray{T}(parent(ac))'
 AbstractMatrix{T}(ac::Adjoint{<:Any,<:InfRanges}) where T<:Real = AbstractVector{T}(parent(ac))'
 AbstractArray{T}(ac::Transpose{<:Any,<:InfRanges}) where T<:Real = transpose(AbstractArray{T}(parent(ac)))

test/runtests.jl

@@ -160,6 +160,14 @@ end
         @test length(1.:.2:∞) == ℵ₀
         @test length(2:-.2:-∞) == ℵ₀
         @test length(2.:-.2:-∞) == ℵ₀
+
+        @testset "IteratorSize" begin
+            @test Base.IteratorSize(1:2:∞) == Base.IsInfinite()
+            @test Base.IteratorSize(1:∞) == Base.IsInfinite()
+            s = Iterators.Stateful(2:∞)
+            @test first(s) == 2
+            @test first(s) == 3
+        end
     end
 
     @testset "intersect" begin