Class: AMQ::BitSet

Inherits:
Object
  • Object
show all
Defined in:
lib/amq/bit_set.rb

Overview

Very minimalistic, pure Ruby implementation of bit set. Inspired by java.util.BitSet, although significantly smaller in scope.

Originally part of amqp gem. Extracted to make it possible for Bunny to use it.

Constant Summary collapse

ADDRESS_BITS_PER_WORD =

API

6
BITS_PER_WORD = 
(1 << ADDRESS_BITS_PER_WORD)
WORD_MASK = 
0xffffffffffffffff

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(nbits) ⇒ BitSet

Returns a new instance of BitSet.

Parameters:

  • Number (Integer) —

    of bits in the set



21
22
23
24
25
 
# File 'lib/amq/bit_set.rb', line 21

def initialize(nbits)
  @nbits = nbits

  self.init_words(nbits)
end

Instance Attribute Details

#words_in_use ⇒ Object (readonly)

Returns the value of attribute words_in_use.



10
11
12
 
# File 'lib/amq/bit_set.rb', line 10

def words_in_use
  @words_in_use
end

Class Method Details

.number_of_trailing_ones(num) ⇒ Object 



93
94
95
96
97
98
 
# File 'lib/amq/bit_set.rb', line 93

def self.number_of_trailing_ones(num)
  0.upto(BITS_PER_WORD) do |bit|
    return bit if num[bit] == 0
  end
  BITS_PER_WORD
end

Instance Method Details

#clear ⇒ Object

Clears all bits in the set



66
67
68
 
# File 'lib/amq/bit_set.rb', line 66

def clear
  self.init_words(@nbits)
end

#get(i) ⇒ Boolean Also known as: []

Fetches flag value for given bit.

Parameters:

  • A (Integer) —

    bit to fetch

Returns:

  • (Boolean) —

    true if given bit is set, false otherwise



43
44
45
46
47
48
 
# File 'lib/amq/bit_set.rb', line 43

def get(i)
  check_range(i)
  w = self.word_index(i)

  (@words[w] & (1 << i % BITS_PER_WORD)) != 0
end

#next_clear_bit ⇒ Object

clear



70
71
72
73
74
75
76
77
78
 
# File 'lib/amq/bit_set.rb', line 70

def next_clear_bit()
  @words.each_with_index do |word, i|
    if word == WORD_MASK
      next
    end
    return i * BITS_PER_WORD + BitSet.number_of_trailing_ones(word)
  end
  -1
end

#set(i) ⇒ Object

Sets (flags) given bit. This method allows bits to be set more than once in a row, no exception will be raised.

Parameters:

  • A (Integer) —

    bit to set



31
32
33
34
35
36
 
# File 'lib/amq/bit_set.rb', line 31

def set(i)
  check_range(i)
  w = self.word_index(i)
  result = @words[w] |= (1 << (i % BITS_PER_WORD))
  result
end

#to_s ⇒ Object

next_clear_bit



80
81
82
83
84
85
86
 
# File 'lib/amq/bit_set.rb', line 80

def to_s
  result = ""
  @words.each do |w|
    result += w.to_s(2).rjust(BITS_PER_WORD,'0') + ":"
  end
  result
end

#unset(i) ⇒ Object

Unsets (unflags) given bit. This method allows bits to be unset more than once in a row, no exception will be raised.

Parameters:

  • A (Integer) —

    bit to unset



55
56
57
58
59
60
61
62
 
# File 'lib/amq/bit_set.rb', line 55

def unset(i)
  check_range(i)
  w = self.word_index(i)
  return if w.nil?

  result = @words[w] &= ~(1 << i % BITS_PER_WORD)
  result
end

#word_index(i) ⇒ Object 



101
102
103
 
# File 'lib/amq/bit_set.rb', line 101

def word_index(i)
  i >> ADDRESS_BITS_PER_WORD
end