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require 'delegate'
require 'forwardable'
module WillPaginate
# a module that page number exceptions are tagged with
module InvalidPage; end
# integer representing a page number
class PageNumber < DelegateClass(Integer)
# a value larger than this is not supported in SQL queries
BIGINT = 9223372036854775807
extend Forwardable
def initialize(value, name)
value = Integer(value)
if 'offset' == name ? (value < 0 or value > BIGINT) : value < 1
raise RangeError, "invalid #{name}: #{value.inspect}"
end
@name = name
super(value)
rescue ArgumentError, TypeError, RangeError => error
error.extend InvalidPage
raise error
end
alias_method :to_i, :__getobj__
def inspect
"#{@name} #{to_i}"
end
def to_offset(per_page)
PageNumber.new((to_i - 1) * per_page.to_i, 'offset')
end
def kind_of?(klass)
super || to_i.kind_of?(klass)
end
alias is_a? kind_of?
end
# Ultrahax: makes `Fixnum === current_page` checks pass
Numeric.extend Module.new {
def ===(obj)
obj.instance_of? PageNumber or super
end
}
# An idemptotent coercion method
def self.PageNumber(value, name = 'page')
case value
when PageNumber then value
else PageNumber.new(value, name)
end
end
end
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