in src/table.jl [846:872]
function build(f::Meta.Field, L::Meta.Union, batch, rb, de, nodeidx, bufferidx, convert)
@debugv 2 "building array: L = $L"
buffer = rb.buffers[bufferidx]
bytes, typeIds = reinterp(UInt8, batch, buffer, rb.compression)
bufferidx += 1
if L.mode == Meta.UnionMode.Dense
buffer = rb.buffers[bufferidx]
bytes2, offsets = reinterp(Int32, batch, buffer, rb.compression)
bufferidx += 1
end
vecs = []
nodeidx += 1
for child in f.children
A, nodeidx, bufferidx = build(child, batch, rb, de, nodeidx, bufferidx, convert)
push!(vecs, A)
end
data = Tuple(vecs)
meta = buildmetadata(f.custom_metadata)
T = juliaeltype(f, meta, convert)
UT = UnionT(f, convert)
if L.mode == Meta.UnionMode.Dense
B = DenseUnion{T,UT,typeof(data)}(bytes, bytes2, typeIds, offsets, data, meta)
else
B = SparseUnion{T,UT,typeof(data)}(bytes, typeIds, data, meta)
end
return B, nodeidx, bufferidx
end