lib/unitwise/compatible.rb
module Unitwise
# Compatible is used to establish compatibility between units, terms, or
# measurements. This is done by determining the objects atomic composition
# represented as a Signed Multiset.
module Compatible
# @api private
def self.included(base)
base.send :include, Comparable
base.send :include, Memoizable unless base < Memoizable
base.send :memoize, :composition, :composition_string
end
def initialize(*args)
super(*args)
freeze
end
# A representation of a unit based on the atoms it's derived from.
# @return [SignedMultiset]
# @api public
def composition
root_terms.reduce(SignedMultiset.new) do |s, t|
s.increment(t.atom.dim, t.exponent) if t.atom
s
end
end
# Define a default #dim for included classes.
# @return [String]
# @api public
def dim
composition_string
end
# A string representation of a unit based on the atoms it's derived from
# @return [String]
# @api public
def composition_string
composition.sort.map do |k, v|
v == 1 ? k.to_s : "#{k}#{v}"
end.join('.')
end
# Determine if this instance is similar to or compatible with other
# @return [true false]
# @api public
def compatible_with?(other)
composition == other.composition
end
# Compare whether the instance is greater, less than or equal to other.
# @return [-1 0 1]
# @api public
def <=>(other)
if other.respond_to?(:composition) && compatible_with?(other)
scalar <=> other.scalar
end
end
end
end