add interval checks for CloseOpen & co.

Author: rfourquet

src/distributions.jl

@@ -171,23 +171,33 @@ struct OpenOpen01{  T<:AbstractFloat} <: OpenOpen{T}   end # interval (0,1)
 struct CloseOpenAB{T<:AbstractFloat} <: CloseOpen{T} # interval [a,b)
     a::T
     b::T
+
+    CloseOpenAB{T}(a::T, b::T) where {T} = (check_interval(a, b); new{T}(a, b))
 end
 
 struct OpenCloseAB{T<:AbstractFloat} <: OpenClose{T} # interval (a,b]
     a::T
     b::T
+
+    OpenCloseAB{T}(a::T, b::T) where {T} = (check_interval(a, b); new{T}(a, b))
 end
 
 struct CloseCloseAB{T<:AbstractFloat} <: CloseClose{T} # interval [a,b]
     a::T
     b::T
+
+    CloseCloseAB{T}(a::T, b::T) where {T} = (check_interval(a, b); new{T}(a, b))
 end
 
 struct OpenOpenAB{T<:AbstractFloat} <: OpenOpen{T} # interval (a,b)
     a::T
     b::T
+
+    OpenOpenAB{T}(a::T, b::T) where {T} = (check_interval(a, b); new{T}(a, b))
 end
 
+check_interval(a, b) = a >= b && throw(ArgumentError("invalid interval specification"))
+
 const FloatInterval_64 = FloatInterval{Float64}
 const CloseOpen01_64   = CloseOpen01{Float64}
 const CloseOpen12_64   = CloseOpen12{Float64}

test/runtests.jl

@@ -265,6 +265,11 @@ end
     @test CloseOpen(1,   2.0)        === CloseOpen(1.0, 2.0)
     @test CloseOpen(1.0, Float32(2)) === CloseOpen(1.0, 2.0)
     @test CloseOpen(big(1), 2) isa CloseOpen{BigFloat}
+
+    for CO in (CloseOpen, CloseClose, OpenOpen, OpenClose)
+        @test_throws ArgumentError CO(1, 1)
+        @test_throws ArgumentError CO(2, 1)
+    end
 end
 
 @testset "rand(::Type{<:Tuple})" begin