Add addmeta() for HDF5 structures

docs/src/api.md

@@ -38,6 +38,7 @@ SummaryFrame
 ```@docs
 H5File
 H5CompoundDataset
+addmeta
 create_dataset
 flush
 ```

src/KM3io.jl

@@ -18,7 +18,7 @@ import UnROOT
 using HDF5
 
 export ROOTFile
-export H5File, H5CompoundDataset, create_dataset
+export H5File, H5CompoundDataset, create_dataset, addmeta
 
 export Direction, Position, UTMPosition, Location, Quaternion, Track, AbstractCalibratedHit
 export Detector, DetectorModule, PMT, Tripod, Hydrophone, center, isbasemodule

src/hdf5/hdf5.jl

@@ -16,6 +16,7 @@ struct H5CompoundDataset{T}
 end
 Base.length(c::H5CompoundDatasetCache) = length(c.buffer)
 isfull(c::H5CompoundDatasetCache) = length(c) >= c.size
+HDF5.read_attribute(cdset::H5CompoundDataset, name::AbstractString) = HDF5.read_attribute(cdset.dset, name)
 
 """
 
@@ -66,6 +67,7 @@ function Base.write(f::H5File, path::AbstractString, data)
     write_dataset(f._h5f, path, data)
 end
 Base.getindex(f::H5File, args...) = getindex(f._h5f, args...)
+HDF5.read_attribute(f::H5File, name::AbstractString) = HDF5.read_attribute(f._h5f, name)
 
 """
 
@@ -88,3 +90,17 @@ function Base.push!(d::H5CompoundDataset{T}, element::T) where T
     push!(d.cache.buffer, element)
     isfull(d.cache) && flush(d)
 end
+
+"""
+
+Attaches key-value-pair meta entries to an HDF5 instance for each field of the
+given object.
+
+"""
+function addmeta(dset::Union{HDF5.Dataset, HDF5.File, HDF5.Group, HDF5.Datatype}, object::T) where T
+    for fieldname in fieldnames(T)
+        attributes(dset)[string(fieldname)] = getfield(object, fieldname)
+    end
+end
+addmeta(cdset::H5CompoundDataset, object) = addmeta(cdset.dset, object)
+addmeta(f::H5File, object) = addmeta(f._h5f, object)

test/hdf5.jl

@@ -39,5 +39,18 @@ end
     write(f, "directly_written_bars", bars)
     @test bars == reinterpret(Bar, f["directly_written_bars"][:])
 
+    addmeta(d, Bar(1, 2.3))
+    @test read_attribute(d, "a") == 1
+    @test read_attribute(d, "b") == 2.3
+
+    d2 = create_dataset(f, "foo", Int32; cache_size=1000)
+    addmeta(d2.dset, Bar(3, 4.5))
+    @test read_attribute(d2, "a") == 3
+    @test read_attribute(d2, "b") == 4.5
+
+    addmeta(f, Bar(6, 7.8))
+    @test read_attribute(f, "a") == 6
+    @test read_attribute(f, "b") == 7.8
+
     close(f)
 end