Internal Iterators versus External Iterators : Iterator « Design Patterns « Ruby

1. Ruby
2. Design Patterns
3. Iterator

Internal Iterators versus External Iterators

class Iterator
  def initialize(array)
    @array = array
    @index = 0
  end

  def has_next?
    @index < @array.length
  end

  def item
    @array[@index]
  end
  def next_item
    value = @array[@index]
    @index += 1
    value
  end
end

def merge(array1, array2)
  merged = []

  iterator1 = Iterator.new(array1)
  iterator2 = Iterator.new(array2)

  while( iterator1.has_next? and iterator2.has_next? )
    if iterator1.item < iterator2.item
      merged << iterator1.next_item
    else
      merged << iterator2.next_item
    end
  end

  while( iterator1.has_next?)
    merged << iterator1.next_item
  end

  while( iterator2.has_next?)
    merged << iterator2.next_item
  end

  merged
end

 

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