support datavalue (#40)

* support datavalue

* use SkipConstructor

Author: Pietro Vertechi

src/StructArrays.jl

@@ -20,6 +20,9 @@ function __init__()
         isstringarray(::WeakRefStrings.StringArray) = true
         default_array(::Type{T}, d) where {T<:Union{AbstractString, Missing}} = WeakRefStrings.StringArray{T}(d)
     end
+    Requires.@require DataValues="e7dc6d0d-1eca-5fa6-8ad6-5aecde8b7ea5" begin
+        Base.@pure SkipConstructor(::Type{<:DataValues.DataValue}) = true
+    end
 end
 
 end # module

test/REQUIRE

@@ -1,3 +1,4 @@
 Tables
 PooledArrays
 WeakRefStrings
+DataValues

test/runtests.jl

@@ -1,6 +1,7 @@
 using StructArrays
 using StructArrays: LazyRow
 import Tables, PooledArrays, WeakRefStrings
+using DataValues: DataValue
 using Test
 
 # write your own tests here
@@ -408,3 +409,13 @@ end
     @test v.a == [i for i in 1:3, j in 1:4]
     @test v.b == [j for i in 1:3, j in 1:4]
 end
+
+@testset "datavalues" begin
+    a = DataValue(2)
+    b = DataValue{Float64}()
+    s = StructArray(i for i in (a, b))
+    @test propertynames(s) == (:hasvalue, :value)
+    @test s.hasvalue == [true, false]
+    @test s.value isa Vector{Real}
+    @test s.value[1] == 2
+end