Class: ArrowFormat::Bitmap

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/arrow-format/bitmap.rb

Instance Method Summary collapse

Constructor Details

#initialize(buffer, offset, n_values) ⇒ Bitmap

Returns a new instance of Bitmap.



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# File 'lib/arrow-format/bitmap.rb', line 21

def initialize(buffer, offset, n_values)
  @buffer = buffer
  @offset = offset
  @n_values = n_values
end

Instance Method Details

#[](i) ⇒ Object 



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# File 'lib/arrow-format/bitmap.rb', line 27

def [](i)
  i += @offset
  (@buffer.get_value(:U8, i / 8) & (1 << (i % 8))) > 0
end

#each ⇒ Object 



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# File 'lib/arrow-format/bitmap.rb', line 32

def each
  return to_enum(__method__) unless block_given?

  # TODO: Optimize
  current = -1
  n_bytes = (@offset + @n_values) / 8
  @buffer.each(:U8, 0, n_bytes) do |offset, value|
    8.times do |i|
      current += 1
      next if current < @offset
      yield((value & (1 << (i % 8))) > 0)
    end
  end
  remained_bits = (@offset + @n_values) % 8
  unless remained_bits.zero?
    value = @buffer.get_value(:U8, n_bytes)
    remained_bits.times do |i|
      current += 1
      next if current < @offset
      yield((value & (1 << (i % 8))) > 0)
    end
  end
end

#popcount ⇒ Object 



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# File 'lib/arrow-format/bitmap.rb', line 56

def popcount
  # TODO: Optimize
  count do |flaged|
    flaged
  end
end