Prototype of the Rouge syntax highighter integration for Asciidoctor. Now bundled with Asciidoctor. See https://github.com/asciidoctor/asciidoctor/blob/master/lib/asciidoctor/syntax_highlighter/rouge.rb

syntax-highlighter-rouge.rb

class RougeSyntaxHighlighter < Asciidoctor::SyntaxHighlighter::Base
  register_for 'rouge'

  def initialize *args
    super
    @requires_stylesheet = nil
    @style = nil
  end

  def highlight?
    library_available?
  end

  def highlight node, source, lang, opts
    lexer = (::Rouge::Lexer.find lang) || ::Rouge::Lexer::PlainText
    lexer_opts = {}
    lexer_opts[:start_inline] = true if lexer.tag == 'php' && !(node.option? 'mixed')
    style = @style = opts[:style]
    style = @style = DEFAULT_STYLE unless style_available? style
    if opts[:css_mode] == :class
      @requires_stylesheet = true
      formatter = ::Rouge::Formatters::HTML.new style
    else
      node.set_option 'inline-css'
      formatter = ::Rouge::Formatters::HTMLInline.new style
    end
    if opts[:line_numbers]
      formatter = ::Rouge::Formatters::HTMLTable.new formatter, code_class: 'code', gutter_class: 'linenos', start_line: opts[:start_line_number]
      if opts[:callouts] && (highlighted = (formatter.format lexer.lex source, lexer_opts).gsub PreRx, '\1')
        return [highlighted, (idx = highlighted.index CodeCellStartTagCs) ? idx + CodeCellStartTagCs.length : nil]
      end
    end
    formatter.format lexer.lex source, lexer_opts
  end

  def format node, lang, opts
    content = super
    if (node.option? 'inline-css') && (pre_style_attr_val = block_style @style)
      content.sub %r/<pre[^>]*/, %(\\& style="#{pre_style_attr_val}")
    else
      content
    end
  end

  def docinfo? location
    @requires_stylesheet && location == :footer
  end

  def docinfo location, doc, opts
    if opts[:linkcss]
      %(<link rel="stylesheet" href="#{doc.normalize_web_path (stylesheet_basename @style), (doc.attr 'stylesdir', ''), false}"#{opts[:self_closing_tag_slash]}>)
    else
      %(<style>
#{read_stylesheet @style}
</style>)
    end
  end

  def write_stylesheet? doc
    @requires_stylesheet
  end

  def write_stylesheet doc, to_dir
    ::File.write (::File.join to_dir, (stylesheet_basename @style)), (read_stylesheet @style)
  end

  module Loader
    private

    def library_available?
      (@@library_status ||= load_library) == :loaded
    end

    def load_library
      (defined? ::Rouge::Lexer) ? :loaded : (Asciidoctor::Helpers.require_library 'rouge', true, :warn).nil? ? :unavailable : :loaded
    end
  end

  module Styles
    include Loader

    def read_stylesheet style
      if library_available?
        @@stylesheet_cache[style ||= DEFAULT_STYLE] ||= (::Rouge::Theme.find style).render scope: BASE_SELECTOR
      else
        '/* Rouge CSS disabled because Rouge is not available. */'
      end
    end

    def stylesheet_basename style
      %(rouge-#{style || DEFAULT_STYLE}.css)
    end

    private

    def block_style style
      @@block_style_cache[style ||= DEFAULT_STYLE] ||= begin
        base_style = (theme = ::Rouge::Theme.find style).base_style
        style = []
        { fg: 'color', bg: 'background-color' }.each do |mode, property_name|
          (val = base_style[mode]) && (style << %(#{property_name}: #{theme.palette val}))
        end
        style.empty? ? nil : (style.join ';')
      end
    end

    def style_available? style
      (::Rouge::Theme.find style) ? true : nil
    end

    @@block_style_cache = {}
    @@stylesheet_cache = {}

    DEFAULT_STYLE = 'github'
    BASE_SELECTOR = '.listingblock .rouge'

    private_constant :BASE_SELECTOR
  end

  include Loader, Styles # adds methods to instance

  CodeCellStartTagCs = '<td class="code">'
  PreRx = %r(<pre\b[^>]*?>(.*?)</pre>)m

  private_constant :CodeCellStartTagCs, :PreRx
end