Broadcast improvements.

src/custom_collections/CatVector.jl

@@ -95,18 +95,22 @@ end
     return dest
 end
 
-Base.@propagate_inbounds catvec_broadcast_vec(x::CatVector, k::Int) = x.vecs[k]
-Base.@propagate_inbounds catvec_broadcast_vec(x::Number, k::Int) = x
+Base.@propagate_inbounds catvec_broadcast_vec(arg::CatVector, range::UnitRange, k::Int) = arg.vecs[k]
+Base.@propagate_inbounds catvec_broadcast_vec(arg::AbstractVector, range::UnitRange, k::Int) = view(arg, range)
+Base.@propagate_inbounds catvec_broadcast_vec(arg::Number, range::UnitRange, k::Int) = arg
 
 @inline function Base.copyto!(dest::CatVector, bc::Broadcast.Broadcasted{Nothing})
     flat = Broadcast.flatten(bc)
     @boundscheck check_cat_vectors_line_up(dest, flat.args...)
+    offset = 1
     @inbounds for i in eachindex(dest.vecs)
         let i = i, f = flat.f, args = flat.args
-            dest′ = catvec_broadcast_vec(dest, i)
-            args′ = map(arg -> catvec_broadcast_vec(arg, i), args)
+            dest′ = dest.vecs[i]
+            range = offset : offset + length(dest′) - 1
+            args′ = map(arg -> catvec_broadcast_vec(arg, range, i), args)
             axes′ = (eachindex(dest′),)
             copyto!(dest′, Broadcast.Broadcasted{Nothing}(f, args′, axes′))
+            offset = last(range) + 1
         end
     end
     return dest

test/test_custom_collections.jl

@@ -175,13 +175,13 @@ Base.axes(m::NonOneBasedMatrix) = ((1:m.m) .- 2, (1:m.n) .+ 1)
         for i in eachindex(x)
             @test x[i] == y[i]
         end
-
-        x .= 0
-        for i in eachindex(y)
-            x[i] = y[i]
-        end
         @test x == y
 
+        y .= 0
+        rand!(x)
+        y .= x .+ y .+ 1
+        @test x .+ 1 == y
+
         allocs = let x=x, vecs=vecs
             @allocated copyto!(x, RigidBodyDynamics.CatVector(vecs))
         end