currency.rb

# @author Fernando Vieira do http://simplesideias.com.br
module Brcobranca #:nodoc:[all]
  module Currency #:nodoc:[all]
    # Implementação feita por Fernando Vieira do http://simplesideias.com.br
    # post http://simplesideias.com.br/usando-number_to_currency-em-modelos-no-rails
    BRL = {:delimiter => ".", :separator => ",", :unit => "R$", :precision => 2, :position => "before"}
    USD = {:delimiter => ',', :separator => ".", :unit => "US$", :precision => 2, :position => "before"}
    DEFAULT = BRL.merge(:unit => "")

    module String #:nodoc:[all]
      def to_number(options={})
        return self.gsub(/,/, '.').to_f if self.numeric?
        nil
      end

      def numeric?
        self =~ /^(\+|-)?[0-9]+((\.|,)[0-9]+)?$/ ? true : false
      end
    end

    module Number #:nodoc:[all]
      def to_currency(options = {})
        number = self
        default   = Brcobranca::Currency::DEFAULT
        options   = default.merge(options)
        precision = options[:precision] || default[:precision]
        unit      = options[:unit] || default[:unit]
        position  = options[:position] || default[:position]
        separator = precision > 0 ? options[:separator] || default[:separator] : ""
        delimiter = options[:delimiter] || default[:delimiter]

        begin
          parts = number.with_precision(precision).split('.')
          number = parts[0].to_i.with_delimiter(delimiter) + separator + parts[1].to_s
          position == "before" ? unit + number : number + unit
        rescue
          number
        end
      end

      def with_delimiter(delimiter=",", separator=".")
        number = self
        begin
          parts = number.to_s.split(separator)
          parts[0].gsub!(/(\d)(?=(\d\d\d)+(?!\d))/, "\\1#{delimiter}")
          parts.join separator
        rescue
          self
        end
      end

      def with_precision(precision=3)
        number = self
        "%01.#{precision}f" % number
      end
    end
  end
end

[ Numeric, String].each do |klass|
  klass.class_eval { include Brcobranca::Currency::Number }
end

[ String ].each do |klass|
  klass.class_eval { include Brcobranca::Currency::String }
end