Class: HDF5::Attribute

Inherits:
Object
  • Object
show all
Defined in:
lib/hdf5/attribute.rb

Instance Method Summary collapse

Constructor Details

#initialize(dataset_id, attr_name) ⇒ Attribute

Returns a new instance of Attribute.

Raises:



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# File 'lib/hdf5/attribute.rb', line 3

def initialize(dataset_id, attr_name)
  @dataset_id = dataset_id
  @attr_name = attr_name
  @attr_id = HDF5::FFI.H5Aopen(@dataset_id, @attr_name, HDF5::DEFAULT_PROPERTY_LIST)
  raise HDF5::Error, 'Failed to open attribute' if @attr_id < 0
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/hdf5/attribute.rb', line 46

def close
  return if @attr_id.nil?

  HDF5::FFI.H5Aclose(@attr_id)
  @attr_id = nil
end

#read ⇒ Object 



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# File 'lib/hdf5/attribute.rb', line 10

def read
  type_id = HDF5::FFI.H5Aget_type(@attr_id)
  space_id = HDF5::FFI.H5Aget_space(@attr_id)

  size = HDF5::FFI.H5Sget_simple_extent_npoints(space_id)

  buffer = \
    case HDF5::FFI.H5Tget_class(type_id)
    when :H5T_INTEGER
      ::FFI::MemoryPointer.new(:int, size)
    when :H5T_FLOAT
      ::FFI::MemoryPointer.new(:double, size)
    when :H5T_STRING
      ::FFI::MemoryPointer.new(:pointer, size)
    else
      raise HDF5::Error, 'Unsupported data type'
    end

  status = HDF5::FFI.H5Aread(@attr_id, type_id, buffer)
  raise HDF5::Error, 'Failed to read attribute' if status < 0

  case HDF5::FFI.H5Tget_class(type_id)
  when :H5T_INTEGER
    buffer.read_array_of_int(size)
  when :H5T_FLOAT
    buffer.read_array_of_double(size)
  when :H5T_STRING
    buffer.read_pointer.read_string
  else
    raise HDF5::Error, 'Unsupported data type'
  end
ensure
  HDF5::FFI.H5Tclose(type_id) if type_id && type_id >= 0
  HDF5::FFI.H5Sclose(space_id) if space_id && space_id >= 0
end