Class: Amazon::Util::PaginatedIterator

Inherits:
Object
  • Object
show all
Defined in:
lib/amazon/util/paginated_iterator.rb

Overview

PaginatedIterator provides an iterator interface to a paginated dataset, buffering the current page. It can be used to stream large result sets which would not fit into memory or only need to be processed in a single pass.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(&feeder) ⇒ PaginatedIterator

feeder should be a block that accepts a pagenumber and returns an array containing the corresponding page worth of results. It should return an empty array when there are no more results in the dataset.



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# File 'lib/amazon/util/paginated_iterator.rb', line 17

def initialize( &feeder )
  @feeder = feeder
  restart
end

Instance Attribute Details

#done ⇒ Object (readonly)

Returns the value of attribute done.



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# File 'lib/amazon/util/paginated_iterator.rb', line 49

def done
  @done
end

Instance Method Details

#each(&block) ⇒ Object

iterates over the remaining items



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# File 'lib/amazon/util/paginated_iterator.rb', line 42

def each( &block ) # :yields: item
  until @done
    item = self.next
    yield item unless item.nil?
  end
end

#hasNext ⇒ Object

checks if we have another item available



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# File 'lib/amazon/util/paginated_iterator.rb', line 36

def hasNext
  fetchpage if @buffer.empty?
  return !@buffer.empty?
end

#next ⇒ Object

returns the next item, or nil if there are no more items



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# File 'lib/amazon/util/paginated_iterator.rb', line 30

def next
  fetchpage if @buffer.empty?
  @buffer.shift
end

#restart ⇒ Object

resets the iterator to start pulling from the first page



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# File 'lib/amazon/util/paginated_iterator.rb', line 23

def restart
  @buffer = []
  @page = 1
  @done = false
end