Add built-in support to write compound data types

src/HDF5.jl

@@ -28,6 +28,7 @@ export @read,
     open_dataset,
     read_dataset,
     write_dataset,
+    write_compound_dataset,
     create_group,
     open_group,
     copy_object,

src/typeconversions.jl

@@ -60,6 +60,15 @@ function datatype(str::VLen{C}) where {C<:CharType}
     Datatype(API.h5t_vlen_create(type_id))
 end
 
+# Compound types
+function datatype(A::AbstractArray{T}) where {T}
+    dtype = API.h5t_create(API.H5T_COMPOUND, sizeof(T))
+    for (idx, fn) in enumerate(fieldnames(T))
+        API.h5t_insert(dtype, fn, fieldoffset(T, idx), datatype(fieldtype(T, idx)))
+    end
+    Datatype(dtype)
+end
+
 # Opaque types
 struct Opaque
     data

test/compound.jl

@@ -146,3 +146,36 @@ end
     @test HDF5.do_reclaim(TTTT) == false
     @test HDF5.do_normalize(TTTT) == true
 end
+
+struct Bar
+    a::Int32
+    b::Float64
+    c::Bool
+end
+
+@testset "write_compound" begin
+    bars = [
+        [Bar(1, 1.1, true) Bar(2, 2.1, false) Bar(3, 3.1, true)]
+        [Bar(4, 4.1, false) Bar(5, 5.1, true) Bar(6, 6.1, false)]
+    ]
+
+    fn = tempname()
+    h5open(fn, "w") do h5f
+        write_dataset(h5f, "the/bar", bars)
+    end
+
+    thebars = h5open(fn, "r") do h5f
+        read(h5f, "the/bar")
+    end
+
+    @test (2, 3) == size(thebars)
+    @test thebars[1, 2].b ≈ 2.1
+    @test thebars[2, 1].a == 4
+    @test thebars[1, 3].c
+
+    thebars_r = reinterpret(Bar, thebars)
+    @test (2, 3) == size(thebars_r)
+    @test thebars_r[1, 2].b ≈ 2.1
+    @test thebars_r[2, 1].a == 4
+    @test thebars_r[1, 3].c
+end