Module: HDF5::StringCodec

Defined in:
lib/hdf5/string_codec.rb

Constant Summary collapse

UTF8 = 
1
VARIABLE_SIZE = 
(1 << (::FFI.type_size(:size_t) * 8)) - 1

Class Method Summary collapse

Class Method Details

.array_shape(value) ⇒ Object

Raises:



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# File 'lib/hdf5/string_codec.rb', line 66

def array_shape(value)
  return [] unless value.is_a?(Array)
  raise HDF5::Error, 'String data must not be empty' if value.empty?

  child_shapes = value.map { |item| array_shape(item) }
  raise HDF5::ShapeError, 'String data must be rectangular' unless child_shapes.uniq.length == 1

  [value.length, *child_shapes.first]
end

.buffer_for(value) ⇒ Object 



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# File 'lib/hdf5/string_codec.rb', line 20

def buffer_for(value)
  buffer_for_values([normalize(value)])
end

.buffer_for_values(values) ⇒ Object 



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# File 'lib/hdf5/string_codec.rb', line 24

def buffer_for_values(values)
  pointers = values.map { |value| ::FFI::MemoryPointer.from_string(normalize(value)) }
  buffer = ::FFI::MemoryPointer.new(:pointer, pointers.length)
  buffer.write_array_of_pointer(pointers)
  [buffer, pointers]
end

.check(status, operation) ⇒ Object

Raises:



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# File 'lib/hdf5/string_codec.rb', line 89

def check(status, operation)
  raise HDF5::Error, "Failed to #{operation}" if status < 0
end

.datatype_id ⇒ Object 



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# File 'lib/hdf5/string_codec.rb', line 8

def datatype_id
  type_id = HDF5::FFI.H5Tcopy(HDF5::FFI.H5T_C_S1)
  raise HDF5::Error, 'Failed to create string datatype' if type_id < 0

  check(HDF5::FFI.H5Tset_size(type_id, VARIABLE_SIZE), 'set variable string size')
  check(HDF5::FFI.H5Tset_cset(type_id, UTF8), 'set UTF-8 string encoding')
  type_id
rescue StandardError
  HDF5::FFI.H5Tclose(type_id) if type_id && type_id >= 0
  raise
end

.normalize(value) ⇒ Object 



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# File 'lib/hdf5/string_codec.rb', line 80

def normalize(value)
  raise HDF5::Error, 'String dataset data must be a String' unless value.is_a?(String)
  raise HDF5::Error, 'Variable-length strings cannot contain NUL bytes' if value.include?("\0")

  value.encode(Encoding::UTF_8)
rescue EncodingError
  raise HDF5::Error, 'String dataset data must be valid UTF-8'
end

.normalize_data(value) ⇒ Object 



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# File 'lib/hdf5/string_codec.rb', line 58

def normalize_data(value)
  return [[normalize(value)], []] if value.is_a?(String)
  return [value.to_a.flatten.map { |item| normalize(item) }, value.shape] if value.is_a?(Numo::RObject)

  shape = array_shape(value)
  [value.flatten.map { |item| normalize(item) }, shape]
end

.read(buffer) ⇒ Object 



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# File 'lib/hdf5/string_codec.rb', line 31

def read(buffer)
  pointer = buffer.read_pointer
  pointer.null? ? nil : pointer.read_string.force_encoding(Encoding::UTF_8)
end

.read_values(buffer, count, shape) ⇒ Object 



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# File 'lib/hdf5/string_codec.rb', line 36

def read_values(buffer, count, shape)
  values = buffer.read_array_of_pointer(count).map do |pointer|
    pointer.null? ? nil : pointer.read_string.force_encoding(Encoding::UTF_8)
  end
  return values.first if shape.empty?

  Numo::RObject.cast(values).reshape(*shape)
end

.string_data?(value) ⇒ Boolean

Returns:



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# File 'lib/hdf5/string_codec.rb', line 45

def string_data?(value)
  return true if value.is_a?(String)

  values = if value.is_a?(Numo::RObject)
             value.to_a.flatten
           elsif value.is_a?(Array)
             value.flatten
           else
             []
           end
  !values.empty? && values.all? { |item| item.is_a?(String) }
end

.variable?(type_id) ⇒ Boolean

Returns:



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# File 'lib/hdf5/string_codec.rb', line 76

def variable?(type_id)
  HDF5::FFI.H5Tis_variable_str(type_id).positive?
end