Rouge is a pure Ruby syntax highlighter. It can highlight over 200 different languages, and output HTML or ANSI 256-color text. Its HTML output is compatible with stylesheets designed for Pygments.

In your Gemfile, add:

gem 'rouge'

or

gem install rouge

Rouge's most common uses are as a Ruby library, as part of Jekyll and as a command line tool.

Here's a quick example of using Rouge as you would any other regular Ruby library:

require 'rouge'

# make some nice lexed html
source = File.read('/etc/bashrc')
formatter = Rouge::Formatters::HTML.new
lexer = Rouge::Lexers::Shell.new
formatter.format(lexer.lex(source))

# Get some CSS
Rouge::Themes::Base16.mode(:light).render(scope: '.highlight')
# Or use Theme#find with string input
Rouge::Theme.find('base16.light').render(scope: '.highlight')

Rouge is Jekyll's default syntax highlighter. Out of the box, Rouge will be used to highlight text wrapped in the {% highlight %} template tags. The {% highlight %} tag provides minimal options: you can specify the language to use and whether to enable line numbers or not. More information is available in the Jekyll docs.

Rouge ships with a rougify command which allows you to easily highlight files in your terminal:

rougify foo.rb
rougify style monokai.sublime > syntax.css

Rouge comes with a number of formatters built-in but as of Rouge 2.0, you are encouraged to write your own formatter if you need something custom.

The built-in formatters are:

• Rouge::Formatters::HTML.new will render your code with standard class names for tokens, with no div-wrapping or other bells or whistles.

• Rouge::Formatters::HTMLInline.new(theme) will render your code with no class names, but instead inline the styling options into the style= attribute. This is good for emails and other systems where CSS support is minimal.

• Rouge::Formatters::HTMLLinewise.new(formatter, class: 'line-%i') will split your code into lines, each contained in its own div. The class option will be used to add a class name to the div, given the line number.

• Rouge::Formatters::HTMLLineHighlighter.new(formatter, highlight_lines: [3, 5]) will split your code into lines and wrap the lines specified by the highlight_lines option in a span with a class name specified by the highlight_line_class option (default: hll).

• Rouge::Formatters::HTMLLineTable.new(formatter, opts={}) will output an HTML table containing numbered lines, each contained in its own table-row. Options are:

  • start_line: 1 - the number of the first row
  • line_id: 'line-%i' - a sprintf template for id attribute with current line number
  • line_class: 'lineno' - a CSS class for each table-row
  • table_class: 'rouge-line-table' - a CSS class for the table
  • gutter_class: 'rouge-gutter' - a CSS class for the line-number cell
  • code_class: 'rouge-code' - a CSS class for the code cell

• Rouge::Formatters::HTMLPygments.new(formatter, css_class='codehilite') wraps the given formatter with div wrappers generally expected by stylesheets designed for Pygments.

• Rouge::Formatters::HTMLTable.new(formatter, opts={}) will output an HTML table containing numbered lines similar to Rouge::Formatters::HTMLLineTable, except that the table from this formatter has just a single table-row. Therefore, while the table is more DOM-friendly for JavaScript scripting, long code lines will mess with the column alignment. Options are:

  • start_line: 1 - the number of the first line
  • line_format: '%i' - a sprintf template for the line number itself
  • table_class: 'rouge-table' - a CSS class for the table
  • gutter_class: 'rouge-gutter' - a CSS class for the gutter
  • code_class: 'rouge-code' - a CSS class for the code column

• Rouge::Formatters::HTMLLegacy.new(opts={}) is a backwards-compatibility class intended for users of Rouge 1.x, with options that were supported then. Options are:

  • inline_theme: nil - use an HTMLInline formatter with the given theme
  • line_numbers: false - use an HTMLTable formatter
  • wrap: true - use an HTMLPygments wrapper
  • css_class: 'codehilite' - a CSS class to use for the Pygments wrapper

• Rouge::Formatters::Terminal256.new(theme) is a formatter for generating highlighted text for use in the terminal. theme must be an instance of Rouge::Theme, or a Hash structure with :theme entry.

If the above formatters are not sufficient, and you wish to customize the layout of the HTML document, we suggest writing your own HTML formatter. This can be accomplished by subclassing Rouge::Formatters::HTML and overriding specific methods:

class MyFormatter < Rouge::Formatters::HTML

  # this is the main entry method. override this to customize the behavior of
  # the HTML blob as a whole. it should receive an Enumerable of (token, value)
  # pairs and yield out fragments of the resulting html string. see the docs
  # for the methods available on Token.
  def stream(tokens, &block)
    yield "<div class='my-outer-div'>"

    tokens.each do |token, value|
      # for every token in the output, we render a span
      yield span(token, value)
    end

    yield "</div>"
  end

  # or, if you need linewise processing, try:
  def stream(tokens, &block)
    token_lines(tokens).each do |line_tokens|
      yield "<div class='my-cool-line'>"
      line_tokens.each do |token, value|
        yield span(token, value)
      end
      yield "</div>"
    end
  end

  # Override this method to control how individual spans are rendered.
  # The value `safe_value` will already be HTML-escaped.
  def safe_span(token, safe_value)
    # in this case, "text" tokens don't get surrounded by a span
    if token == Token::Tokens::Text
      safe_value
    else
      "<span class=\"#{token.shortname}\">#{safe_value}</span>"
    end
  end
end

• debug: false will print a trace of the lex on stdout.

• parent: '' allows you to specify which language the template is inside.

• scope: '.highlight' sets the CSS selector to which styles are applied, e.g.:

  Rouge::Themes::MonokaiSublime.render(scope: 'code')

Rouge's documentation is available at rouge-ruby.github.io/docs/.

Rouge is compatible with all versions of Ruby from 2.0.0 onwards. It has no external dependencies.

Rouge only supports UTF-8 strings. If you'd like to highlight a string with a different encoding, please convert it to UTF-8 first.

• Middleman:
  • middleman-syntax (@bhollis)
  • middleman-rouge (@Linuus)
• RDoc: rdoc-rouge (@zzak)
• Rails: Rouge::Rails (@jacobsimeon)

We're always excited to welcome new contributors to Rouge. By it's nature, a syntax highlighter relies for its success on submissions from users of the languages being highlighted. You can help Rouge by filing bug reports or developing new lexers.

Everyone interacting in Rouge and its sub-projects' code bases is expected to follow the Rouge Code of Conduct.

Rouge uses GitHub's Issues to report bugs. You can choose from one of our templates or create a custom issue. Issues that have not been active for a year are automatically closed by GitHub's Probot.

NOTE: Please don't submit lexers that are copy-pasted from other files. These submission will be rejected and we don't want you to waste your time.

We want to make it as easy as we can for anyone to contribute a lexer to Rouge. To help get you started, we have a shiny new guide on lexer development in the documentation. The best place is to start there.

If you get stuck and need help, submit a pull request with what you have and make it clear in your submission that the lexer isn't finished yet. We'll do our best to answer any questions you have and sometimes the best way to do that is with actual code.

Once you've cloned the repository from GitHub, you can test the core of Rouge simply by running rake (no bundle exec required). You can also run a single test file by setting the TEST environment variable to the path of the desired test. For example, to test just the ruby lexer (located at path spec/lexers/ruby_spec.rb) simply run the following:

TEST=spec/lexers/ruby_spec.rb rake

To test a lexer visually, run rackup from the top-level working directory and you should have a web server running and ready to go. Visit https://localhost:9292 to see the full list of Rouge's lexers.

Once you've selected a particular lexer, you can add ?debug=1 to your URL string to see a lot of helpful debugging info printed on stdout.

Rouge uses Semantic Versioning 2.0.0.

Rouge is largely the result of the hard work of unpaid volunteers. It was originally developed by Jeanine Adkisson (@jneen) and is currently maintained by Jeanine Adkisson, Drew Blessing (@dblessing), Goro Fuji (@gfx) and Tan Le (@tancnle).

Rouge is released under the MIT license. Please see the LICENSE file for more information.