From 56e1d8e8f9c756d85d7608468cb41574c5da042b Mon Sep 17 00:00:00 2001
From: "Tamas K. Papp" <tkpapp@gmail.com>
Date: Fri, 20 Oct 2017 22:26:25 +0200
Subject: [PATCH] Add length (#23)

See discussion at
https://github.com/JuliaMath/IntervalSets.jl/issues/21, this should
fix the issue.
---
 src/closed.jl    | 5 +++++
 test/runtests.jl | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/src/closed.jl b/src/closed.jl
index 21e6f18..85c1ef7 100644
--- a/src/closed.jl
+++ b/src/closed.jl
@@ -94,6 +94,10 @@ function width{T}(A::ClosedInterval{T})
     max(zero(_width), _width)   # this works when T is a Date
 end
 
+length{T <: Integer}(A::ClosedInterval{T}) = max(0, Int(A.right - A.left) + 1)
+
+length(A::ClosedInterval{Date}) = max(0, Dates.days(A.right - A.left) + 1)
+
 function convert{R<:AbstractUnitRange,I<:Integer}(::Type{R}, i::ClosedInterval{I})
     R(minimum(i), maximum(i))
 end
@@ -101,3 +105,4 @@ end
 range{I<:Integer}(i::ClosedInterval{I}) = convert(UnitRange{I}, i)
 
 Base.promote_rule{T1,T2}(::Type{ClosedInterval{T1}}, ::Type{ClosedInterval{T2}}) = ClosedInterval{promote_type(T1, T2)}
+
diff --git a/test/runtests.jl b/test/runtests.jl
index 0ebed0e..7d8efd5 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -79,12 +79,19 @@ using Base.Test
             @test width(ClosedInterval(A, B)) == Base.Dates.Day(59)
             @test width(ClosedInterval(B, A)) == Base.Dates.Day(0)
             @test isempty(ClosedInterval(B, A))
+            @test length(ClosedInterval(A, B)) ≡ 60
+            @test length(ClosedInterval(B, A)) ≡ 0
         end
 
         @test width(ClosedInterval(3,7)) ≡ 4
         @test width(ClosedInterval(4.0,8.0)) ≡ 4.0
 
         @test promote(1..2, 1.0..2.0) === (1.0..2.0, 1.0..2.0)
+
+        @test length(I) == 4
+        @test length(J) == 0
+        # length deliberately not defined for non-integer intervals
+        @test_throws MethodError length(1.2..2.4)
     end
 end