Support empty components (#162)

* no reduce

* primitivetype

* some changes

* treat dict like nt

* abstractdict

* delete comment

* simpler recursive_eltype

* Update componentarray.jl

* empty components

* more tests

Author: Shambles

src/componentarray.jl

@@ -143,14 +143,11 @@ end
 make_carray_args(::Type{T}, nt) where {T} = make_carray_args(Vector{T}, nt)
 function make_carray_args(A::Type{<:AbstractArray}, nt)
     T = recursive_eltype(nt)
-    init = _isbitstype(T) ? T[] : []
+    init = isbitstype(T) ? T[] : []
     data, idx = make_idx(init, nt, 0)
     return (A(data), Axis(idx))
 end
 
-_isbitstype(::Type{<:Union{T, Nothing, Missing}}) where {T} = isbitstype(T)
-_isbitstype(T) = isbitstype(T)
-
 # Builds up data vector and returns appropriate AbstractAxis type for each input type
 function make_idx(data, nt::Union{NamedTuple, AbstractDict}, last_val)
     len = recursive_length(nt)
@@ -238,6 +235,11 @@ end
 last_index(x) = last(x)
 last_index(x::ViewAxis) = last_index(viewindex(x))
 last_index(x::AbstractAxis) = last_index(last(indexmap(x)))
+function last_index(f::FlatAxis)
+    nt = indexmap(f)
+    length(nt) == 0 && return 0
+    return last_index(last(nt))
+end
 
 # Reduce singleton dimensions
 remove_nulls() = ()

src/utils.jl

@@ -42,10 +42,11 @@ recursive_length(a::AbstractArray{T,N}) where {T<:Number,N} = length(a)
 recursive_length(a::AbstractArray) = recursive_length.(a) |> sum
 recursive_length(nt::NamedTuple) = values(nt) .|> recursive_length |> sum
 recursive_length(::Union{Nothing, Missing}) = 1
+recursive_length(nt::NamedTuple{(), Tuple{}}) = 0
 
 # Find the highest element type
-recursive_eltype(nt::NamedTuple) = mapreduce(recursive_eltype, promote_type, nt)
-recursive_eltype(x::Vector) = mapreduce(recursive_eltype, promote_type, x)
-recursive_eltype(x::Dict) = mapreduce(recursive_eltype, promote_type, values(x))
-recursive_eltype(::AbstractArray{T,N})  where {T<:Number, N}= T
+recursive_eltype(nt::NamedTuple) = isempty(nt) ? Base.Bottom : mapreduce(recursive_eltype, promote_type, nt)
+recursive_eltype(x::Vector{Any}) = isempty(x) ? Base.Bottom : mapreduce(recursive_eltype, promote_type, x)
+recursive_eltype(x::Dict) = isempty(x) ? Base.Bottom : mapreduce(recursive_eltype, promote_type, values(x))
+recursive_eltype(::AbstractArray{T,N}) where {T<:Number, N} = T
 recursive_eltype(x) = typeof(x)

test/runtests.jl

@@ -112,6 +112,16 @@ end
     # Issue #116
     # Part 2: Arrays of arrays
     @test_throws Exception ComponentVector(a = [[3], [4, 5]], b = 1)
+
+    # empty components
+    for T in [Int64, Int32, Float64, Float32, ComplexF64, ComplexF32]
+        @test ComponentArray(a = T[]) == ComponentVector{T}(a = T[])
+        @test ComponentArray(a = T[], b = T[]) == ComponentVector{T}(a = T[], b = T[])
+        @test ComponentArray(a = T[], b = (;)) == ComponentVector{T}(a = T[], b = T[])
+        @test ComponentArray(a = Any[one(Int32)], b=T[]) == ComponentVector{T}(a = [one(T)], b = T[])
+    end
+    @test ComponentArray(NamedTuple()) == ComponentVector{Any}()
+    @test_broken  ComponentArray(a=[])
 end
 
 @testset "Attributes" begin
@@ -612,4 +622,4 @@ end
 
 @testset "GPU" begin
     include("gpu_tests.jl")
-end
+end