Convert human readable number to float in Ruby

string_decoder.rb

# Convert human entered string into number
class StringDecoder
  # Hash with powers of 10 by names
  POWERS = {
    'trillion' => 10**12,
    'trillions' => 10**12,
    'billion' => 10**9,
    'billions' => 10**9,
    'million' => 10**6,
    'millions' => 10**6,
    'thousand' => 10**3,
    'thousands' => 10**3,
  }.freeze

  # Only one public method for service object: #call
  def call(input)
    # Return if input is numeric (and don't forget to strip spaces and commas)
    return input.gsub(/[\s,]/, '').to_f if float? input.gsub(/[\s,]/, '')

    result = 0

    # First line: insert spacebar if there is no one between integer and word
    # Second line: split array by space
    # Third line: convert each word to its numeric format
    # Fourth line: slice array by 2 elements
    # Fifth line: multiply each chunk and sum everything
    input.gsub(/(?<=[\d])(?=[а-яА-Я])/, ' ')
         .split(' ')
         .map { |i| POWERS[i] ? POWERS[i].to_f : i.to_f }
         .each_slice(2) do |slice|
      result += slice.inject(:*)
    end

    result
  end

  private

  # Check if given string may be converted to float
  def float?(input)
    input[/\A[\d]+[\.]?[\d]*\z/] == input
  end
end