SimpleEdge comparison (#134)

* SimpleEdge comparison

* Update src/SimpleGraphs/simpleedge.jl

Co-authored-by: Guillaume Dalle <[email protected]>

* Update src/SimpleGraphs/simpleedge.jl

Co-authored-by: Guillaume Dalle <[email protected]>

* Update test/simplegraphs/simpleedge.jl

Co-authored-by: Guillaume Dalle <[email protected]>

---------

Co-authored-by: Guillaume Dalle <[email protected]>

Author: CarloLucibello

src/SimpleGraphs/simpleedge.jl

@@ -1,4 +1,4 @@
-import Base: Pair, Tuple, show, ==, hash
+import Base: Pair, Tuple, show, ==, hash, isless
 import Graphs: AbstractEdge, src, dst, reverse
 
 abstract type AbstractSimpleEdge{T<:Integer} <: AbstractEdge{T} end
@@ -34,3 +34,4 @@ function ==(e1::AbstractSimpleEdge, e2::AbstractSimpleEdge)
     return (src(e1) == src(e2) && dst(e1) == dst(e2))
 end
 hash(e::AbstractSimpleEdge, h::UInt) = hash(src(e), hash(dst(e), h))
+isless(e1::AbstractSimpleEdge, e2::AbstractSimpleEdge) = (src(e1) < src(e2)) || ((src(e1) == src(e2)) && (dst(e1) < dst(e2)))

test/simplegraphs/simpleedge.jl

@@ -35,4 +35,12 @@
         @test reverse(ep1) == re
         @test sprint(show, ep1) == "Edge 1 => 2"
     end
+
+    @testset "comparison" begin
+        @test SimpleEdge(1, 2) < SimpleEdge(1, 3) 
+        @test SimpleEdge(1, 2) < SimpleEdge(2, 3)
+        @test SimpleEdge(1, 2) < SimpleEdge(2, 1)
+        @test SimpleEdge(1, 2) <= SimpleEdge(1, 2)
+        @test SimpleEdge(2, 3) > SimpleEdge(1, 2)
+    end
 end