Contents

class Measured::Unit
  include Comparable

  attr_reader :name, :names, :conversion_amount, :conversion_unit, :unit_system

  def initialize(name, aliases: [], value: nil, unit_system: nil)
    @name = name.to_s
    @names = ([@name] + aliases.map(&:to_s)).sort
    @conversion_amount, @conversion_unit = parse_value(value) if value
    @unit_system = unit_system
  end

  def with_unit_system(unit_system)
    self.class.new(
      name,
      aliases: names - [name],
      value: conversion_string,
      unit_system: unit_system
    )
  end

  def to_s
    if conversion_string
      "#{ @name } (#{ conversion_string })"
    else
      @name
    end
  end

  def inspect
    "#<Measured::Unit: #{ @name } (#{ @names.join(", ") }) #{ conversion_string }>"
  end

  def <=>(other)
    if self.class == other.class
      names_comparison = @names <=> other.names
      if names_comparison != 0
        names_comparison
      else
        @conversion_amount <=> other.conversion_amount
      end
    else
      @name <=> other
    end
  end

  def inverse_conversion_amount
    1 / conversion_amount.to_r
  end

  private

  def conversion_string
    "#{ conversion_amount } #{ conversion_unit }" if @conversion_amount || @conversion_unit
  end

  def parse_value(tokens)
    tokens = tokens.split(" ") if tokens.is_a?(String)

    raise Measured::UnitError, "Cannot parse 'number unit' or [number, unit] formatted tokens from #{tokens}." unless tokens.size == 2

    [tokens[0].to_r, tokens[1]]
  end
end

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
measured-2.0.0.pre2	lib/measured/unit.rb