#207 Syntax Highlighting (revised)

May 11, 2012 | 8 minutes | Views, Plugins

Here I compare several syntax highlighting solutions and show how to use Pygments in a Rails app. I also show how to integrate it with Markdown and add caching.

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          terminal
        
gem install coderay pygments.rb uv
ruby syntax_benchmark.rb

          Gemfile
        
gem 'pygments.rb'
gem 'redcarpet'

          snippets/show.html.erb
        
<%= raw Pygments.highlight(@snippet.code, lexer: @snippet.language) %>

          app/assets/stylesheets/pygments.css.erb
        
<%= Pygments.css(style: "colorful") %>

          articles/show.html.erb
        
<%= markdown @article.content %>

          application_helper.rb
        
module ApplicationHelper
  class HTMLwithPygments < Redcarpet::Render::HTML
    def block_code(code, language)
      sha = Digest::SHA1.hexdigest(code)
      Rails.cache.fetch ["code", language, sha].join('-') do
        Pygments.highlight(code, lexer: language)
      end
    end
  end

  def markdown(text)
    renderer = HTMLwithPygments.new(hard_wrap: true, filter_html: true)
    options = {
      autolink: true,
      no_intra_emphasis: true,
      fenced_code_blocks: true,
      lax_html_blocks: true,
      strikethrough: true,
      superscript: true
    }
    Redcarpet::Markdown.new(renderer, options).render(text).html_safe
  end
end

          syntax_benchmark.rb
        
require "rubygems"
require "benchmark"
require "coderay"
require "pygments"
require "uv"

repeat = 50
content = File.read(__FILE__)

# run it once to initialize
CodeRay.scan(content, "ruby").div(css: :class)
Pygments.highlight(content, lexer: "ruby")
Uv.parse(content, "xhtml", "ruby", true, "amy")

Benchmark.bm(11) do |b|
  b.report("coderay") do
    repeat.times { CodeRay.scan(content, "ruby").div(css: :class) }
  end

  b.report("pygments") do
    repeat.times { Pygments.highlight(content, lexer: "ruby") }
  end
  
  b.report("ultraviolet") do
    repeat.times { Uv.parse(content, "xhtml", "ruby", true, "amy") }
  end
end