add irb option for the cli script

bin/gollum

@@ -14,9 +14,7 @@ Options:
 HELP
 
 require 'optparse'
-
 require 'rubygems'
-require 'gollum/frontend/app'
 
 exec = {}
 options = {}
@@ -31,11 +29,47 @@ opts = OptionParser.new do |opts|
     puts "Gollum " + Gollum::VERSION
     exit 0
   end
+
+  opts.on("--irb", "Start an irb process with gollum loaded for the current wiki.") do
+    options['irb'] = true
+  end
 end
 
 # Read command line options into `options` hash
 opts.parse!
 
 $path = ARGV[0] || Dir.pwd
 
-Precious::App.run!(options)
+if options['irb']
+  require 'irb'
+  # http://jameskilton.com/2009/04/02/embedding-irb-into-your-ruby-application/
+  module IRB # :nodoc:
+    def self.start_session(binding)
+      unless @__initialized
+        args = ARGV
+        ARGV.replace(ARGV.dup)
+        IRB.setup(nil)
+        ARGV.replace(args)
+        @__initialized = true
+      end
+
+      workspace = WorkSpace.new(binding)
+
+      irb = Irb.new(workspace)
+
+      @CONF[:IRB_RC].call(irb.context) if @CONF[:IRB_RC]
+      @CONF[:MAIN_CONTEXT] = irb.context
+
+      catch(:IRB_EXIT) do
+        irb.eval_input
+      end
+    end
+  end
+
+  require 'gollum'
+  wiki = Gollum::Wiki.new $path
+  IRB.start_session binding
+else
+  require 'gollum/frontend/app'
+  Precious::App.run!(options)
+end