Class: Json::Streamer::JsonStreamer

Inherits:
Object
  • Object
show all
Defined in:
lib/json/streamer.rb

Instance Method Summary collapse

Constructor Details

#initialize(file_io, chunk_size = 1000) ⇒ JsonStreamer

Returns a new instance of JsonStreamer.



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# File 'lib/json/streamer.rb', line 7

def initialize(file_io, chunk_size = 1000)
  @parser = JSON::Stream::Parser.new

  @file_io = file_io
  @chunk_size = chunk_size

  @object_nesting_level = 0
  @current_key = nil
  @aggregator = {}
  @temp_aggregator_keys = {}

  @parser.start_object {start_object}
  @parser.start_array {start_array}
  @parser.key {|k| key(k)}
  @parser.value {|v| value(v)}

end

Instance Method Details

#get_objects_from_level(yield_nesting_level) ⇒ Object 



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# File 'lib/json/streamer.rb', line 25

def get_objects_from_level(yield_nesting_level)
  @yield_nesting_level = yield_nesting_level

  # Callback containing yield has be defined in the method called via block
  @parser.end_object do
    if @object_nesting_level.eql? @yield_nesting_level
      yield @aggregator[@object_nesting_level].clone
      # TODO probably can be faster than reject!{true}
      @aggregator[@object_nesting_level].reject!{true}
    else
      merge_up
    end

    @object_nesting_level -= 1
  end

  @parser.end_array do
    if @object_nesting_level.eql? @yield_nesting_level
      yield @aggregator[@object_nesting_level].clone
      # TODO probably can be faster than reject!{true}
      @aggregator[@object_nesting_level].reject!{true}
    else
      merge_up
    end

    @object_nesting_level -= 1
  end

  @file_io.each(@chunk_size) do |chunk|
    @parser << chunk
  end
end

#key(k) ⇒ Object 



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# File 'lib/json/streamer.rb', line 70

def key k
  @current_key = k
end

#merge_up ⇒ Object 



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# File 'lib/json/streamer.rb', line 82

def merge_up
  return if @object_nesting_level == 1
  previous_object_nesting_level = @object_nesting_level - 1
  if @aggregator[previous_object_nesting_level].kind_of? Array
    @aggregator[previous_object_nesting_level] << @aggregator[@object_nesting_level]
  else
    @aggregator[previous_object_nesting_level][@temp_aggregator_keys[previous_object_nesting_level]] = @aggregator[@object_nesting_level]
  end

  @aggregator.delete(@object_nesting_level)
  @aggregator
end

#start_array ⇒ Object 



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# File 'lib/json/streamer.rb', line 64

def start_array
  @temp_aggregator_keys[@object_nesting_level] = @current_key
  @object_nesting_level += 1
  @aggregator[@object_nesting_level] = []
end

#start_object ⇒ Object 



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# File 'lib/json/streamer.rb', line 58

def start_object
  @temp_aggregator_keys[@object_nesting_level] = @current_key
  @object_nesting_level += 1
  @aggregator[@object_nesting_level] = {}
end

#value(v) ⇒ Object 



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# File 'lib/json/streamer.rb', line 74

def value v
  if @aggregator[@object_nesting_level].kind_of? Array
    @aggregator[@object_nesting_level] << v
  else
    @aggregator[@object_nesting_level][@current_key] = v
  end
end