42 lines
761 B
Ruby
42 lines
761 B
Ruby
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# This file contains the Ruby code from book of
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# "Data Structures and Algorithms
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# with Object-Oriented Design Patterns in Ruby"
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# by Bruno R. Preiss.
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#
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# Copyright (c) 2004 by Bruno R. Preiss, P.Eng. All rights reserved.
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class DequeAsLinkedList < QueueAsLinkedList
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alias_method :queueHead, :head
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include DequeMethods
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def initialize
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super
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end
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alias_method :head, :queueHead
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def enqueueHead(obj)
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@list.prepend(obj)
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@count += 1
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end
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alias_method :dequeueHead, :dequeue
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def tail
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raise ContainerEmpty if @count == 0
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@list.last
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end
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alias_method :enqueueTail, :enqueue
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def dequeueTail
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raise ContainerEmpty if @count == 0
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result = @list.last
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@list.extract(result)
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@count -= 1
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result
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end
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end
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