88 lines
1.3 KiB
Ruby
88 lines
1.3 KiB
Ruby
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# Provide a way to access the elements of an aggregate object sequentially
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# without exposing its underlying representation.
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# Iteration entity
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class Account
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attr_reader :balance
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def initialize(balance)
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@balance = balance
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end
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end
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# Collection class
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class Bank
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include Enumerable
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def initialize
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@accounts = []
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end
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def each(&block)
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@accounts.each(&block)
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end
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def add(account)
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@accounts << account
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end
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end
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# Usage
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bank = Bank.new
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bank.add Account.new(100)
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bank.add Account.new(150)
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bank.add Account.new(175)
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puts bank.map { |account| account.balance }
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# Internal iterator
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class Collection
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def initialize(array)
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@array = array
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@index = 0
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end
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def has_next?
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@index < @array.length
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end
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def next_item
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value = @array[@index]
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@index += 1
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value
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end
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def iterate(&block)
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while has_next?
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block.call(next_item) if block_given?
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end
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end
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end
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# Usage
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collection = Collection.new([1, 2, 3, 4, 5])
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collection.iterate { |elem| puts elem }
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# External iterator
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class Collection
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def initialize(array)
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@array = array
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@index = 0
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end
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def has_next?
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@index < @array.length
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end
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def next_item
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value = @array[@index]
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@index += 1
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value
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end
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end
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# Usage
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collection = Collection.new([1, 2, 3, 4, 5])
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puts "Item: #{collection.next_item}" while collection.has_next?
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