Rakefile

require "bundler/gem_tasks"
require "jekyll"
require "listen"

def listen_ignore_paths(base, options)
 [
 /_config\.ya?ml/,
 /_site/,
 /\.jekyll-metadata/
 ]
end

def listen_handler(base, options)
 site = Jekyll::Site.new(options)
 Jekyll::Command.process_site(site)
 proc do |modified, added, removed|
 t = Time.now
 c = modified + added + removed
 n = c.length
 relative_paths = c.map{ |p| Pathname.new(p).relative_path_from(base).to_s }
 print Jekyll.logger.message("Regenerating:", "#{relative_paths.join(", ")} changed... ")
 begin
 Jekyll::Command.process_site(site)
 puts "regenerated in #{Time.now - t} seconds."
 rescue => e
 puts "error:"
 Jekyll.logger.warn "Error:", e.message
 Jekyll.logger.warn "Error:", "Run jekyll build --trace for more information."
 end
 end
end

task :preview do
 base = Pathname.new('.').expand_path
 options = {
 "source" => base.join('test').to_s,
 "destination" => base.join('test/_site').to_s,
 "force_polling" => false,
 "serving" => true,
 "theme" => "minimal-mistakes-jekyll"
 }

 options = Jekyll.configuration(options)

 ENV["LISTEN_GEM_DEBUGGING"] = "1"
 listener = Listen.to(
 base.join("_data"),
 base.join("_includes"),
 base.join("_layouts"),
 base.join("_sass"),
 base.join("assets"),
 options["source"],
 :ignore => listen_ignore_paths(base, options),
 :force_polling => options['force_polling'],
 &(listen_handler(base, options))
 )

 begin
 listener.start
 Jekyll.logger.info "Auto-regeneration:", "enabled for '#{options["source"]}'"

 unless options['serving']
 trap("INT") do
 listener.stop
 puts " Halting auto-regeneration."
 exit 0
 end

 loop { sleep 1000 }
 end
 rescue ThreadError
 # You pressed Ctrl-C, oh my!
 end

 Jekyll::Commands::Serve.process(options)
end