module AttrBitwise::ClassMethods
Public Instance Methods
Usage :
attr_bitwise :payment_types, mapping: [:slots, :credits], column_name: 'payment_types_value'
# File lib/attr_bitwise.rb, line 63 def attr_bitwise(name, column_name: nil, mapping:) column_name = "#{name}_value" unless column_name.present? # build mapping bitwise_mapping = build_mapping(mapping, name) # mask to symbols helper define_method("#{name}") { send(:value_getter, column_name, bitwise_mapping) } define_method("#{name}=") do |values_or_symbols_array| send(:value_setter, column_name, Array(values_or_symbols_array), bitwise_mapping) end # masks symbol presence define_method("#{name.to_s.singularize}?") do |value_or_symbol| send(:value?, column_name, force_to_bitwise_value(value_or_symbol, bitwise_mapping)) end # add value to mask define_method("add_#{name.to_s.singularize}") do |value_or_symbol| send(:add_value, column_name, force_to_bitwise_value(value_or_symbol, bitwise_mapping)) end # remove value from mask define_method("remove_#{name.to_s.singularize}") do |value_or_symbol| send(:remove_value, column_name, force_to_bitwise_value(value_or_symbol, bitwise_mapping)) end # compute values union against mask define_method("#{name}_union") do |*mixed_array| self.class.bitwise_union(*mixed_array, name) end # compute values intersection against mask define_method("#{name}_intersection") do |*mixed_array| self.class.bitwise_intersection(*mixed_array, name) end end
given a values_arr ay array, return a possible matches
for a intersection
with PAYMENT_TYPES_MAPPING = { credits: 0b001, slots: 0b010, paypal: 0b100 } see www.calleerlandsson.com/2015/02/16/flags-bitmasks-and-unix-file-system-permissions-in-ruby/
bitwise_intersection
(:slots, :credits, ‘payment_types’) => [0b101, 0b100, 0b011, 0b111]
# File lib/attr_bitwise.rb, line 129 def bitwise_intersection(*mixed_array, name) values_array = mixed_array.map { |v| to_bitwise_values(v, name) } mapping = mapping_from_name(name) mask = [] val = values_array.reduce(&:|) mapping.values.each do |pv| mask << (pv | val) end mask.uniq end
given a payment_values array, return a possible matches
for a union
with PAYMENT_TYPES_MAPPING = { credits: 0b001, slots: 0b010, paypal: 0b100 } see www.calleerlandsson.com/2015/02/16/flags-bitmasks-and-unix-file-system-permissions-in-ruby/
bitwise_union
(:slots, :credits, ‘payment_types’) => [0b011, 0b111]
# File lib/attr_bitwise.rb, line 108 def bitwise_union(*mixed_array, name) values_array = mixed_array.map { |v| to_bitwise_values(v, name) } mapping = mapping_from_name(name) mask = [] values_array.each do |pv| mapping.values.each do |pvv| mask << (pv | pvv) end end mask.uniq end
Given a raw value (int) or a symbol, return proper raw value (int)
# File lib/attr_bitwise.rb, line 155 def force_to_bitwise_value(value_or_symbol, mapping) if value_or_symbol.is_a?(Symbol) mapping[value_or_symbol] else value_or_symbol.to_i end end
given an Object, return proper Fixnum value, depending of mapping
# File lib/attr_bitwise.rb, line 143 def to_bitwise_values(object, name) mapping = mapping_from_name(name) if object.is_a?(Array) object.map { |v| force_to_bitwise_value(v, mapping) } elsif object.is_a?(Hash) object.values.map { |v| force_to_bitwise_value(v, mapping) } else force_to_bitwise_value(object, mapping) end end
Private Instance Methods
build internal bitwise key-value mapping
it add a zero value, needed for bits operations
each sym get a power of 2 value
# File lib/attr_bitwise.rb, line 179 def build_mapping(symbols, name) mapping = {}.tap do |hash| if symbols.is_a?(Hash) validate_user_defined_values!(symbols, name) hash.merge!(symbols.sort_by{|k,v| v}.to_h) else symbols.each_with_index do |key, i| hash[key] = 2**i end end hash[:empty] = 0 end # put mapping in unique constant const_mapping_name = "#{name}_mapping".upcase const_set(const_mapping_name, mapping) end
return mapping given a bitwise name
# File lib/attr_bitwise.rb, line 171 def mapping_from_name(name) const_get("#{name}_mapping".upcase) end
# File lib/attr_bitwise.rb, line 196 def validate_user_defined_values!(hash, name) hash.select{|key,value| (Math.log2(value) % 1.0)!=0}.tap do |invalid_options| if invalid_options.any? raise(ArgumentError, "#{name} value should be a power of two number (#{invalid_options.to_s})") end end end