Basic 'rbx docs' command support.

This is preliminary and only supports automatic invocation of the
browser on Darwin and Linux. This can be extended to other platforms
very simply.

lib/bin/docs.rb

@@ -0,0 +1,3 @@
+require 'rubinius/documentation'
+
+Rubinius::Documentation.main

lib/rubinius/.gitignore

@@ -1 +1,4 @@
 build_config.rb
+
+# generated static documentation site
+documentation/site

lib/rubinius/documentation.rb

@@ -0,0 +1,123 @@
+# Built-in documentation site, server, and browser launcher.
+#
+# A static documentation site is generated from documentation
+# source files. The static site is served by Rubinius using
+# the WEBrick server in the Ruby standard library. Code from
+# the launchy gem has been adapted to launch a web browser to
+# view the documentation.
+
+require 'rbconfig'
+require 'webrick'
+
+module Rubinius
+  class Documentation
+    def self.main
+      docs = new
+      docs.options
+      docs.show
+    end
+
+    def initialize
+      @server_only = false
+      @port = nil
+      @browser = nil
+      @running = false
+      @documents = nil
+      @url = nil
+    end
+
+    def port
+      @port ||= 35421
+    end
+
+    def documents
+      @documents ||= File.expand_path("../documentation/site", __FILE__)
+    end
+
+    def url
+      @url ||= "http://localhost:#{port}"
+    end
+
+    def browser
+      return if @server_only
+
+      sleep 0.1 until @running
+
+      unless @browser
+        case RbConfig::CONFIG['host_os']
+        when /darwin/
+          @browser = "open"
+        when /linux/
+          browsers = %w[ xdg-open exo-open gnome-open kfmclient htmlview
+                         firefox opera mozilla galeon seamonkey ]
+          @browser = browsers.find { |x| `which #{x}`; x if $?.success? }
+        else
+          STDERR.puts "Unknown system #{RbConfig::CONFIG['host_os']}"
+          STDERR.puts "Use --browser option to specify the browser to run"
+        end
+      end
+
+      return unless @browser
+
+      Thread.new do
+        command = "#{@browser} #{url}"
+        system command
+
+        unless $?.success?
+          STDERR.puts "\nUnable to start browser: #{command}"
+          STDERR.puts "You can view the documentation by visiting #{url} in your browser"
+        end
+      end
+    end
+
+    def start_hook
+      lambda { @running = true }
+    end
+
+    def server
+      Thread.new do
+        puts "Starting Rubinius Documentation Server..."
+        puts "Type ^C to exit\n\n"
+
+        server = WEBrick::HTTPServer.new(:Port => port,
+                                         :DocumentRoot => documents,
+                                         :StartCallback => start_hook)
+
+        [:INT, :TERM].each do |signal|
+          trap(signal) { server.shutdown }
+        end
+
+        server.start
+      end
+    end
+
+    def options(argv=ARGV)
+      options = Rubinius::Options.new "Usage: rbx docs [options]", 23
+
+      options.on "-p", "--port", "NUM", "Listen on port NUM" do |port|
+        @port = port
+      end
+
+      options.on "-s", "--server", "Only start server, not browser" do
+        @server_only = true
+      end
+
+      options.on("-b", "--browser", "CMD",
+                 "Start browser using CMD passing the URL") do |browser|
+        @browser = browser
+      end
+
+      options.help
+      options.doc ""
+
+      options.parse argv
+    end
+
+    def show
+      s = server
+      b = browser
+      b.join if b
+      s.join
+    end
+  end
+end