module ActiveSupport # Provides accurate date and time measurements using Date#advance and # Time#advance, respectively. It mainly supports the methods on Numeric, # such as in this example: # # 1.month.ago # equivalent to Time.now.advance(:months => -1) class Duration < BasicObject attr_accessor :value, :parts def initialize(value, parts) #:nodoc: @value, @parts = value, parts end # Adds another Duration or a Numeric to this Duration. Numeric values # are treated as seconds. def +(other) if Duration === other Duration.new(value + other.value, @parts + other.parts) else Duration.new(value + other, @parts + [[:seconds, other]]) end end # Subtracts another Duration or a Numeric from this Duration. Numeric # values are treated as seconds. def -(other) self + (-other) end def -@ #:nodoc: Duration.new(-value, parts.map { |type,number| [type, -number] }) end def is_a?(klass) #:nodoc: klass == Duration || super end # Returns true if other is also a Duration instance with the # same value, or if other == value. def ==(other) if Duration === other other.value == value else other == value end end def self.===(other) #:nodoc: other.is_a?(Duration) rescue super end # Calculates a new Time or Date that is as far in the future # as this Duration represents. def since(time = ::Time.now) sum(1, time) end alias :from_now :since # Calculates a new Time or Date that is as far in the past # as this Duration represents. def ago(time = ::Time.now) sum(-1, time) end alias :until :ago def inspect #:nodoc: consolidated = parts.inject(::Hash.new(0)) { |h,part| h[part.first] += part.last; h } [:years, :months, :days, :minutes, :seconds].map do |length| n = consolidated[length] "#{n} #{n == 1 ? length.to_s.singularize : length.to_s}" if n.nonzero? end.compact.to_sentence end protected def sum(sign, time = ::Time.now) #:nodoc: parts.inject(time) do |t,(type,number)| if t.acts_like?(:time) || t.acts_like?(:date) if type == :seconds t.since(sign * number) else t.advance(type => sign * number) end else raise ::ArgumentError, "expected a time or date, got #{time.inspect}" end end end private def method_missing(method, *args, &block) #:nodoc: value.send(method, *args) end end end