1 files changed, 71 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/number_helper/number_to_human.rb b/activesupport/lib/active_support/number_helper/number_to_human.rb
new file mode 100644
index 0000000000..2b57c75720
--- /dev/null
+++ b/activesupport/lib/active_support/number_helper/number_to_human.rb
@@ -0,0 +1,71 @@
+require 'active_support/number_helper/number_converter'
+require 'active_support/number_helper/number_to_rounded'
+
+module ActiveSupport
+  module NumberHelper
+    class NumberToHumanConverter < NumberConverter # :nodoc:
+
+      DECIMAL_UNITS = { 0 => :unit, 1 => :ten, 2 => :hundred, 3 => :thousand, 6 => :million, 9 => :billion, 12 => :trillion, 15 => :quadrillion,
+        -1 => :deci, -2 => :centi, -3 => :mili, -6 => :micro, -9 => :nano, -12 => :pico, -15 => :femto }
+
+      self.namespace        = :human
+      self.need_valid_float = true
+
+      def convert # :nodoc:
+        @number = Float(@number)
+
+        # for backwards compatibility with those that didn't add strip_insignificant_zeros to their locale files
+        unless options.key?(:strip_insignificant_zeros)
+          options[:strip_insignificant_zeros] = true
+        end
+
+        units = opts[:units]
+        exponent = calculate_exponent(units)
+        @number = @number / (10 ** exponent)
+
+        unit = determine_unit(units, exponent)
+
+        rounded_number = NumberToRoundedConverter.new(@number, options).execute
+        format.gsub(/%n/, rounded_number).gsub(/%u/, unit).strip
+      end
+
+      private
+
+        def format
+          options[:format] || translate_in_locale('human.decimal_units.format')
+        end
+
+        def determine_unit(units, exponent)
+          exp = DECIMAL_UNITS[exponent]
+          case units
+          when Hash
+            units[exp] || ''
+          when String, Symbol
+            I18n.translate("#{units}.#{exp}", :locale => options[:locale], :count => number.to_i)
+          else
+            translate_in_locale("human.decimal_units.units.#{exp}", count: number.to_i)
+          end
+        end
+
+        def calculate_exponent(units)
+          exponent = number != 0 ? Math.log10(number.abs).floor : 0
+          unit_exponents(units).find { |e| exponent >= e } || 0
+        end
+
+        def unit_exponents(units)
+          inverted_decimal_units = DECIMAL_UNITS.invert
+          case units
+          when Hash
+            units
+          when String, Symbol
+            I18n.translate(units.to_s, :locale => options[:locale], :raise => true)
+          when nil
+            translate_in_locale("human.decimal_units.units", raise: true)
+          else
+            raise ArgumentError, ":units must be a Hash or String translation scope."
+          end.keys.map { |e_name| inverted_decimal_units[e_name] }.sort_by{ |e| -e }
+        end
+
+    end
+  end
+end