Class: FastExists::BitArray

Inherits:
Object
  • Object
show all
Defined in:
lib/fast_exists/bit_array.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(size) ⇒ BitArray

Returns a new instance of BitArray.

Raises:



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# File 'lib/fast_exists/bit_array.rb', line 9

def initialize(size)
  raise InvalidArgumentError, "BitArray size must be positive" if size <= 0

  @size = size
  @bytesize = (size + 7) / 8
  @bytes = ("\x00" * @bytesize).b
  @mutex = Mutex.new
end

Instance Attribute Details

#size ⇒ Object (readonly)

Returns the value of attribute size.



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# File 'lib/fast_exists/bit_array.rb', line 7

def size
  @size
end

Class Method Details

.from_s(raw_bytes, size) ⇒ Object 



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# File 'lib/fast_exists/bit_array.rb', line 71

def self.from_s(raw_bytes, size)
  bit_array = new(size)
  bit_array.to_s_load(raw_bytes)
  bit_array
end

Instance Method Details

#bytesize ⇒ Object 



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# File 'lib/fast_exists/bit_array.rb', line 63

def bytesize
  @bytesize
end

#clear ⇒ Object 



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# File 'lib/fast_exists/bit_array.rb', line 42

def clear
  @mutex.synchronize do
    @bytes = ("\x00" * @bytesize).b
  end
  true
end

#count_ones ⇒ Object Also known as: popcount 



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# File 'lib/fast_exists/bit_array.rb', line 49

def count_ones
  count = 0
  @bytes.each_byte do |b|
    # Kernighan's popcount per byte
    while b > 0
      count += 1
      b &= (b - 1)
    end
  end
  count
end

#set(index) ⇒ Object 



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# File 'lib/fast_exists/bit_array.rb', line 18

def set(index)
  validate_index!(index)
  byte_idx = index / 8
  bit_idx = index % 8

  @mutex.synchronize do
    current_byte = @bytes.getbyte(byte_idx)
    new_byte = current_byte | (1 << bit_idx)
    @bytes.setbyte(byte_idx, new_byte)
  end
  true
end

#set?(index) ⇒ Boolean Also known as: get

Returns:

  • (Boolean) 


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# File 'lib/fast_exists/bit_array.rb', line 31

def set?(index)
  validate_index!(index)
  byte_idx = index / 8
  bit_idx = index % 8

  byte = @bytes.getbyte(byte_idx)
  (byte & (1 << bit_idx)) != 0
end

#to_s ⇒ Object 



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# File 'lib/fast_exists/bit_array.rb', line 67

def to_s
  @mutex.synchronize { @bytes.dup }
end

#to_s_load(raw_bytes) ⇒ Object 



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# File 'lib/fast_exists/bit_array.rb', line 77

def to_s_load(raw_bytes)
  @mutex.synchronize do
    raise InvalidArgumentError, "Byte length mismatch" if raw_bytes.bytesize != @bytesize
    @bytes = raw_bytes.dup.b
  end
end