Handle empty inner range (#40)

When the inner range is empty, all points in the outer range are part
of the edge. Previously, however, the iterator would hang, causing
timeouts for ImageFiltering's test suite.

Project.toml

@@ -1,7 +1,7 @@
 name = "TiledIteration"
 uuid = "06e1c1a7-607b-532d-9fad-de7d9aa2abac"
 author = ["Tim Holy <[email protected]>"]
-version = "0.4.1"
+version = "0.4.2"
 
 [deps]
 ArrayInterface = "4fba245c-0d91-5ea0-9b3e-6abc04ee57a9"

src/TiledIteration.jl

@@ -80,7 +80,7 @@ Find the next index in `outer` that is not in `inner` if `I` is not an edge site
     # If all of (I2, ..., IN) are in inner, then we can skip iterating I1 ∈ inner1
     # and jump ahead to I1 = last(inner1). On the other hand if any of (I2, ..., IN)
     # are not in inner we keep iterating over I1 ∈ inner1.
-    while I.I[1] == first(iter.inner)[1] && all(map(in, tail(I.I), tail(iter.inner.indices)))
+    while I.I[1] ∈ iter.inner.indices[1] && all(map(in, tail(I.I), tail(iter.inner.indices)))
         state = (last(iter.inner)[1], tail(I.I)...)
         I = CartesianIndex(_inc(state, iter.outer))
     end

test/runtests.jl

@@ -174,6 +174,14 @@ end
     for it in iter
         @test it ∈ iter.outer
     end
+
+    # empty inner
+    iter = EdgeIterator((1:4,), (3:2,))
+    @test collect(iter) == [CartesianIndex(1),
+                            CartesianIndex(2),
+                            CartesianIndex(3),
+                            CartesianIndex(4),
+                            ]
 end
 
 @testset "padded sizes" begin