69 lines
1.1 KiB
Ruby
69 lines
1.1 KiB
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 StackAsLinkedList < Stack
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def initialize
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super
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@list = SinglyLinkedList.new
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end
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def purge
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@list.purge
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super
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end
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def push(obj)
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@list.prepend(obj)
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@count += 1
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end
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def pop
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raise ContainerEmpty if @count == 0
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result = @list.first
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@list.extract(result)
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@count -= 1
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return result
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end
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def top
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raise ContainerEmpty if @count == 0
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return @list.first
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end
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def each(&block)
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@list.each(&block)
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end
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attr_reader :list
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class Iterator < Opus8::Iterator
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def initialize(stack)
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@position = stack.list.head
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end
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def more?
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not @position.nil?
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end
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def succ
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if more?
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result = @position.datum
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@position = @position.succ
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else
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result = nil
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end
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return result
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end
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end
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def iter
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Iterator.new(self)
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end
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end
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