Sbromberger/inbounds bfs (#754)

* get rid of unions in edge iters

* f

* inbounds on critical BFS loops

* test fix

src/graphtypes/simplegraphs/simpleedgeiter.jl

@@ -17,7 +17,8 @@ end
 eltype(::Type{SimpleEdgeIter{SimpleGraph{T}}}) where {T} = SimpleGraphEdge{T}
 eltype(::Type{SimpleEdgeIter{SimpleDiGraph{T}}}) where {T} = SimpleDiGraphEdge{T}
 
-function edge_start(g::Union{SimpleGraph{T}, SimpleDiGraph{T}}) where {T <: Integer}
+function edge_start(g::AbstractSimpleGraph)
+    T = eltype(g)
     s = one(T)
     while s <= nv(g)
         isempty(fadj(g, s)) || return SimpleEdgeIterState(s, 1)
@@ -26,7 +27,7 @@ function edge_start(g::Union{SimpleGraph{T}, SimpleDiGraph{T}}) where {T <: Inte
     return SimpleEdgeIterState(zero(T), 1)
 end
 
-function edge_next(g::Union{SimpleGraph{T}, SimpleDiGraph{T}}, 
+function edge_next(g::AbstractSimpleGraph, 
     state::SimpleEdgeIterState{T}) where {T <: Integer}
     s = state.s
     di = state.di

src/traversals/bfs.jl

@@ -65,23 +65,26 @@ For vertices in disconnected components the default distance is -1.
 function gdistances!(g::AbstractGraph, source, dists)
     T = eltype(g)
     n = nv(g)
-    fill!(dists, -1)
+    fill!(dists, typemax(T))
+    seen = zeros(Bool, n)
     queue = Vector{T}(n)
-    for i in 1:length(source)
+    @inbounds for i in 1:length(source)
         queue[i] = source[i]
         dists[source[i]] = 0
+        seen[source[i]] = true
     end
     head = 1
     tail = length(source)
     while head <= tail
         current = queue[head]
         distance = dists[current] + 1
         head += 1
-        for j in out_neighbors(g, current)
-            if dists[j] == -1
+        @inbounds for j in out_neighbors(g, current)
+            if !seen[j]
                 dists[j] = distance
                 tail += 1
                 queue[tail] = j
+                seen[j] = true
             end
         end
     end

test/traversals/bfs.jl

@@ -13,7 +13,7 @@ import LightGraphs: tree
     for g in testgraphs(g6)
         @test @inferred(gdistances(g, 2)) == [1, 0, 2, 1, 2]
         @test @inferred(gdistances(g, [1, 2])) == [0, 0, 1, 1, 2]
-        @test @inferred(gdistances(g, [])) == [-1, -1, -1, -1, -1]
+        @test @inferred(gdistances(g, [])) == fill(typemax(eltype(g)), 5)
     end
 
     gx = Graph(5)