class Flagpole

Public: Initialize the set of flags.

value - An Integer with the initial value of the set. flags - The name of the flags you’re using.

# File lib/flagpole.rb, line 6
def initialize(value = 0, flags)
  @flags = flags.zip(bitmap(value, flags.size)).to_h
end

Public: Get a specific flag by name.

key - One of the flag names passed to the initializer.

Returns Boolean.

# File lib/flagpole.rb, line 15
def [](key)
  @flags.fetch(key)
end

Public: Set a specific flag by name.

flag - One of the flag names passed to the initializer. value - A Boolean.

Returns nothing. Raises ArgumentError if passed a flag that isn’t in the set.

# File lib/flagpole.rb, line 26
def []=(flag, val)
  fail ArgumentError, "#{flag} isn't a valid flag" unless @flags.key?(flag)
  @flags[flag] = val
end

Public: Returns a Hash with all the flags and their current values.

# File lib/flagpole.rb, line 39
def to_h
  @flags
end

Public: Returns the current value of the flag set as an Integer.

# File lib/flagpole.rb, line 32
def to_i
  @flags.each_value.with_index.inject(0) do |flag, (bit, power)|
    flag | (bit ? 1 : 0) * 2**power
  end
end

Public: Find the integer value of a single flag, regardless of whether it is set or not. This value can then be added/substracted from the integer value of this set for low-level manipulation of the flag set.

flag - The name of a flag.

Returns an Integer. Raises ArgumentError if passed a flag that isn’t in the set.

# File lib/flagpole.rb, line 51
def value_of(flag)
  fail ArgumentError, "#{flag} isn't a valid flag" unless @flags.key?(flag)
  2 ** @flags.keys.index(flag)
end

Internal: Generate the list of bits that make a given number. Each index of the array corresponds to the bit for 2**index.

Returns an Array of Booleans.

# File lib/flagpole.rb, line 60
def bitmap(num, size)
  Array.new(size).map.with_index { |_, i| num[i] == 1 }
end