Class: Properb::Generators::ArrayGenerator

Inherits:
Properb::Generator show all
Defined in:
lib/properb/generators/array_generator.rb

Instance Method Summary collapse

Methods inherited from Properb::Generator

#map, #or, #reject, #select, #sized, #to_properb_generator

Constructor Details

#initialize(generator, length: 0) ⇒ ArrayGenerator 



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# File 'lib/properb/generators/array_generator.rb', line 4

def initialize(generator, length: 0...)
  @generator = generator
  @length = length
end

Instance Method Details

#generate_value(random, size) ⇒ Object 



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# File 'lib/properb/generators/array_generator.rb', line 9

def generate_value(random, size)
  if @length.is_a?(Range)
    length = random.random_number(@length.min..(@length.end || (@length.min + size)))
    min_length = @length.min
  else
    length = min_length = @length
  end
  values = (0...length).map { @generator.generate_value(random, size) }
  ShrinkTree.new(
    values.map(&:value),
    shrink(values, min_length)
  )
end

#shrink(values, min_length) ⇒ Object 



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# File 'lib/properb/generators/array_generator.rb', line 23

def shrink(values, min_length)
  Enumerator.new do |out|
    cutoff = (values.length / 2).ceil
    if cutoff > min_length
      out << ShrinkTree.new(
        values[cutoff..].map(&:value),
        shrink(values[cutoff..], min_length)
      )
      out << ShrinkTree.new(
        values[...-cutoff].map(&:value),
        shrink(values[...-cutoff], min_length)
      )
    end
    if values.length > min_length
      # Try removing individual items in the vector
      (0...values.length).each do |i|
        new_values = values[0...i] + values[i + 1...]
        out << ShrinkTree.new(
          new_values.map(&:value),
          shrink(new_values, min_length)
        )
      end
    end
    # Try shrinking the individual items in the vector
    (0...values.length).each do |i|
      values[i].children.each do |value|
        new_values = values[0...i] + [value] + values[i + 1...]
        out << ShrinkTree.new(
          new_values.map(&:value),
          shrink(new_values, min_length)
        )
      end
    end
    # Try shrinking pairs of items in the vector
    (0...values.length).each do |i| # rubocop:disable Style/CombinableLoops
      values[i].children.each do |first_value|
        new_values = values[0...i] + [first_value] + values[i + 1...]
        (0...values.length).each do |j|
          new_values[j].children.each do |second_value|
            newer_values = new_values[0...j] + [second_value] + new_values[j + 1...]
            out << ShrinkTree.new(
              newer_values.map(&:value),
              shrink(newer_values, min_length)
            )
          end
        end
      end
    end
  end
end