class BanditMask

Maps name to value in the global list of defined bits.

class MyMask < BanditMask
  bit :read, 0b001
  bit :write, 0b010
  bit :execute, 0b100
end

# File lib/banditmask.rb, line 35
def self.bit(name, value)
  bits.update name => value
end

Returns a Hash mapping all defined names to their respective bits.

class MyMask < BanditMask
  bit :read, 0b01
  bit :write, 0b10
end

MyMask.bits # => { :read => 1, :write => 2 }

# File lib/banditmask.rb, line 23
def self.bits
  @bits ||= {}
end

Enables the bit named bit. Returns self, so calls to << can be chained. (Think Array#<<.) Raises ArgumentError if bit does not correspond to a bit that was previously defined with BanditMask.bit.

class MyMask < BanditMask
  bit :read, 0b01
  bit :write, 0b10
end

mask = MyMask.new       # => #<MyMask:0x007f9ebd44ae40 @bitmask=0>
mask << :read << :write # => #<MyMask:0x007f9ebd44ae40 @bitmask=3>

# File lib/banditmask.rb, line 72
def <<(bit)
  @bitmask |= bit_value(bit)
  self
end

Returns true if other is an instance of the same class as self and they have the same bitmask.

class MyMask < BanditMask
  bit :read, 0b01
  bit :write, 0b10
end

class MyOtherMask < BanditMask
  bit :chocolate, 0b01
  bit :vanilla, 0b10
end

a = MyMask.new 0b1
b = MyMask.new 0b1
c = MyMask.new 0b0
d = MyOtherMask.new 0b1

a == b # => true
a == c # => false
a == d # => false

# File lib/banditmask.rb, line 115
def ==(other)
  other.class == self.class && other.bitmask == bitmask
end

Returns an array of names of the currently enabled bits.

class MyMask < BanditMask
  bit :read, 0b01
  bit :write, 0b10
end

mask = MyMask.new 0b01
mask.bits # => [:read]

# File lib/banditmask.rb, line 55
def bits
  self.class.bits.select { |bit, _| include? bit }.keys
end

Returns an object hash. Two BanditMask objects have identical hashes if they have identical bitmasks and are instances of the same class.

# File lib/banditmask.rb, line 124
def hash
  [bitmask, self.class].hash
end

Returns true if every bit in bits is enabled and false otherwise. Raises ArgumentError if bits is empty or if any element in bits does not correspond to a bit that was previously defined with BanditMask.bit.

class MyMask < BanditMask
  bit :read, 0b001
  bit :write, 0b010
  bit :execute, 0b100
end

mask = MyMask.new 0b101

mask.include? :read           # => true
mask.include? :write          # => false
mask.include? :execute        # => true

mask.include? :read, :write   # => false
mask.include? :read, :execute # => true

# File lib/banditmask.rb, line 147
def include?(*bits)
  raise ArgumentError, 'wrong number of arguments (0 for 1+)' if bits.empty?
  bits.all? { |bit| bitmask & bit_value(bit) != 0 }
end

Returns integer value of current bitmask.

# File lib/banditmask.rb, line 41
def to_i
  bitmask
end

Returns a new instance with the current bitmask plus bit. Raises ArgumentError if bit does not correspond to a bit that was previously defined by BanditMask.bit.

class MyMask < BanditMask
  bit :read, 0b01
  bit :write, 0b10
end

mask = MyMask.new 0b01
mask | :write # => #<MyMask:0x007f9e0bcf5d90 @bitmask=3>

# File lib/banditmask.rb, line 89
def |(bit)
  self.class.new bitmask | bit_value(bit)
end

Returns the integer value for the bit named bit. Raises ArgumentError if bit has not been previously defined with BanditMask.bit.

# File lib/banditmask.rb, line 157
def bit_value(bit)
  self.class.bits.fetch(bit) do
    raise ArgumentError, "undefined bit: #{bit.inspect}"
  end
end