Add VNAlgorithm and dispatch clique_number to very_nauty

Project.toml

@@ -10,6 +10,6 @@ very_nauty_jll = "be6384bf-868f-57ad-9feb-9e32886bc996"
 
 [compat]
 CBinding = "1.1.0"
-Graphs = "1.12.0"
+Graphs = "1.14"
 julia = "1.10"
 very_nauty_jll = "1.1.2"

src/VNGraphs.jl

@@ -1,6 +1,6 @@
 module VNGraphs
 
-export VNGraph
+export VNGraph, VNAlgorithm
 
 import Graphs
 
@@ -118,4 +118,21 @@ Graphs.vertices(g::VNGraph) = 1:nnodes(g)
 
 Graphs.add_edge!(g::VNGraph, e::Graphs.SimpleGraphEdge) = graph_add_edge(g,e.src-1,e.dst-1)
 
+"""Select the `very_nauty` implementation of an operation that Graphs.jl also defines."""
+struct VNAlgorithm end
+
+const VN_LOCK = ReentrantLock()
+
+function Graphs.clique_number(g::VNGraph, ::VNAlgorithm)
+    lock(VN_LOCK) do
+        Int(graph_clique_number(g))
+    end
+end
+
+function Graphs.clique_number(g::Graphs.AbstractSimpleGraph, alg::VNAlgorithm)
+    Graphs.is_directed(g) &&
+        throw(ArgumentError("clique_number is defined for undirected graphs only"))
+    return Graphs.clique_number(VNGraph(g), alg)
+end
+
 end

test/test_vnalgorithm.jl

@@ -0,0 +1,31 @@
+@testitem "clique_number dispatches to very_nauty" begin
+
+import Graphs
+using VNGraphs
+
+for (n, p) in ((10, 0.3), (15, 0.4), (20, 0.3), (25, 0.5), (12, 0.7), (18, 0.9))
+    for t in 1:5
+        g = Graphs.erdos_renyi(n, p)
+        @test Graphs.clique_number(g, VNAlgorithm()) == Graphs.clique_number(g)
+        @test Graphs.clique_number(VNGraph(g), VNAlgorithm()) == Graphs.clique_number(g)
+    end
+end
+
+@test Graphs.clique_number(Graphs.complete_graph(6), VNAlgorithm()) == 6
+@test Graphs.clique_number(Graphs.path_graph(4), VNAlgorithm()) == 2
+@test Graphs.clique_number(Graphs.SimpleGraph(5), VNAlgorithm()) == 1
+@test Graphs.clique_number(Graphs.SimpleGraph(1), VNAlgorithm()) == 1
+@test Graphs.clique_number(Graphs.complete_graph(6), VNAlgorithm()) isa Int
+@test_throws ArgumentError Graphs.clique_number(Graphs.SimpleDiGraph(3), VNAlgorithm())
+@test Graphs.clique_number(Graphs.SimpleGraph(0), VNAlgorithm()) == 0
+
+gs = [Graphs.erdos_renyi(30, 0.6) for _ in 1:4]
+ref = [Graphs.clique_number(g) for g in gs]
+agreed = Threads.Atomic{Int}(0)
+Threads.@threads for k in 1:64
+    i = mod1(k, 4)
+    Graphs.clique_number(gs[i], VNAlgorithm()) == ref[i] && Threads.atomic_add!(agreed, 1)
+end
+@test agreed[] == 64
+
+end