Class: Json::Streamer::JsonStreamer

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(file_io = nil, chunk_size = 1000) ⇒ JsonStreamer

Returns a new instance of JsonStreamer.



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# File 'lib/json/streamer/json_streamer.rb', line 10

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

  @file_io = file_io
  @chunk_size = chunk_size

  @current_level = -1
  @aggregator = {}
  @aggregator_keys = {}

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

Instance Attribute Details

#aggregator ⇒ Object (readonly)

Returns the value of attribute aggregator.



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

def aggregator
  @aggregator
end

#parser ⇒ Object (readonly)

Returns the value of attribute parser.



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# File 'lib/json/streamer/json_streamer.rb', line 8

def parser
  @parser
end

Instance Method Details

#<<(data) ⇒ Object 



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

def <<(data)
  @parser << data
end

#add_value(value) ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 69

def add_value(value)
  if array_level?(@current_level)
    @aggregator[@current_level] << value
  else
    @aggregator[@current_level][@current_key] = value
  end
end

#array_level?(nesting_level) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/json/streamer/json_streamer.rb', line 115

def array_level?(nesting_level)
  @aggregator[nesting_level].is_a?(Array)
end

#end_level(type) ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 77

def end_level(type)
  if yield_object?
    yield @aggregator[@current_level].clone
    reset_current_level(type)
  else
    merge_up
  end

  @current_level -= 1
end

#get(nesting_level: -1,, key: nil, yield_values: true, symbolize_keys: false) ⇒ Object

Callbacks containing ‘yield` have to be defined in the method called via block otherwise yield won’t work



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# File 'lib/json/streamer/json_streamer.rb', line 30

def get(nesting_level: -1, key: nil, yield_values: true, symbolize_keys: false)
  @yield_level = nesting_level
  @yield_key = key
  @yield_values = yield_values
  @symbolize_keys = symbolize_keys

  @parser.value do |v|
    value(v) { |desired_object| yield desired_object }
  end

  @parser.end_object do
    end_level(Hash.new) { |desired_object| yield desired_object }
  end

  @parser.end_array do
    end_level(Array.new) { |desired_object| yield desired_object }
  end

  @file_io.each(@chunk_size) { |chunk| @parser << chunk } if @file_io
end

#key(k) ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 59

def key(k)
  @current_key = @symbolize_keys ? k.to_sym : k
end

#merge_up ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 119

def merge_up
  return if @current_level.zero?

  if array_level?(previous_level)
    @aggregator[previous_level] << @aggregator[@current_level]
  else
    @aggregator[previous_level][previous_key] = @aggregator[@current_level]
  end

  @aggregator.delete(@current_level)
end

#new_level(type) ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 96

def new_level(type)
  reset_current_key if array_level?(@current_level)
  set_aggregator_key
  @current_level += 1
  reset_current_level(type)
end

#next_level ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 135

def next_level
  @current_level + 1
end

#previous_key ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 139

def previous_key
  @aggregator_keys[previous_level]
end

#previous_level ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 131

def previous_level
  @current_level - 1
end

#reset_current_key ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 111

def reset_current_key
  @current_key = nil
end

#reset_current_level(type) ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 103

def reset_current_level(type)
  @aggregator[@current_level] = type
end

#set_aggregator_key ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 107

def set_aggregator_key
  @aggregator_keys[@current_level] = @current_key
end

#start_array ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 55

def start_array
  new_level(Array.new)
end

#start_object ⇒ Object 



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# File 'lib/json/streamer/json_streamer.rb', line 51

def start_object
  new_level(Hash.new)
end

#value(value) {|value| ... } ⇒ Object

Yields:



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# File 'lib/json/streamer/json_streamer.rb', line 63

def value(value)
  reset_current_key if array_level?(@current_level)
  yield value if yield_value?
  add_value(value)
end

#yield_object? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/json/streamer/json_streamer.rb', line 88

def yield_object?
  @current_level.eql?(@yield_level) or (not @yield_key.nil? and @yield_key == previous_key)
end

#yield_value? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/json/streamer/json_streamer.rb', line 92

def yield_value?
  @yield_values and ((next_level).eql?(@yield_level) or (not @yield_key.nil? and @yield_key == @current_key))
end