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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
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
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