gistfile1.rb

require 'yaml'

class FrontMatter
  YAML_REGEX = /\A(---\s*\n.*?\n?)^(---\s*$\n?)/m

  attr_accessor :source, :results, :output

  def initialize(source)
    @source = source
    parse
  end

  private

  def parse(source)
    if source =~ YAML_REGEX
      front_matter = YAML.load($1)
      output       = source.sub(YAML_REGEX, "")
    end
    @results = front_matter || {}
    @output  = output || source
  end

end

gistfile2.rb

require 'yaml'

class FrontMatter
  YAML_REGEX = /\A(---\s*\n.*?\n?)^(---\s*$\n?)/m

  attr_accessor :source, :results, :output

  def initialize(source)
    @source = source
    @results, @output = parse(source).values_at :results, :output
  end

  private

  def parse(source)
    if source =~ YAML_REGEX
      front_matter = YAML.load($1)
      output       = source.sub(YAML_REGEX, "")
    end
    { results: (front_matter || {}), output: (output || source), }
  end

end