Split the BSON logic out to a separate gem

- changed the BSON constant to BSON_CODER and scoped it inside
  of a module

- changed the directory layout for all of the BSON related files

- updated the C extension to find the BSON files at their new
  directory locations

- updated the C extension to use better/safer macros for accessing
  the C API; extension now compiles cleanly under rubinius/rbx

- changed directory layout for BSON related tests

- modified the Rakefile to understand the new layout

lib/mongo_bson.rb

@@ -0,0 +1,40 @@
+$:.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
+
+module Mongo
+  module BSON
+    VERSION = "0.19.2"
+  end
+end
+
+begin
+  # Need this for running test with and without c ext in Ruby 1.9.
+  raise LoadError if ENV['TEST_MODE'] && !ENV['C_EXT']
+  require 'mongo_ext/cbson'
+  raise LoadError unless defined?(CBson::VERSION) && CBson::VERSION == Mongo::BSON::VERSION
+  require 'mongo_bson/bson_c'
+  module Mongo
+    BSON_CODER = BSON_C
+  end
+rescue LoadError
+  require 'mongo_bson/bson_ruby'
+  module Mongo
+    BSON_CODER = BSON_RUBY
+  end
+  warn "\n**Notice: C extension not loaded. This is required for optimum MongoDB Ruby driver performance."
+  warn "  You can install the extension as follows:\n  gem install mongo_ext\n"
+  warn "  If you continue to receive this message after installing, make sure that the"
+  warn "  mongo_ext gem is in your load path and that the mongo_ext and mongo gems are of the same version.\n"
+end
+
+require 'mongo_bson/types/binary'
+require 'mongo_bson/types/code'
+require 'mongo_bson/types/dbref'
+require 'mongo_bson/types/objectid'
+require 'mongo_bson/types/regexp_of_holding'
+require 'mongo_bson/types/min_max_keys'
+
+require 'base64'
+require 'mongo_bson/ordered_hash'
+require 'mongo_bson/byte_buffer'
+require 'mongo_bson/bson_ruby'
+require 'mongo_bson/exceptions'

lib/mongo_bson/exceptions.rb

@@ -0,0 +1,36 @@
+# --
+# Copyright (C) 2008-2010 10gen Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ++
+
+module Mongo
+  # Generic Mongo Ruby Driver exception class.
+  class MongoRubyError < StandardError; end
+
+  # Raised when MongoDB itself has returned an error.
+  class MongoDBError < RuntimeError; end
+
+  # Raised when given a string is not valid utf-8 (Ruby 1.8 only).
+  class InvalidStringEncoding < MongoRubyError; end
+
+  # Raised when attempting to initialize an invalid ObjectID.
+  class InvalidObjectID < MongoRubyError; end
+
+  # Raised when trying to insert a document that exceeds the 4MB limit or
+  # when the document contains objects that can't be serialized as BSON.
+  class InvalidDocument < MongoDBError; end
+
+  # Raised when an invalid name is used.
+  class InvalidName < RuntimeError; end
+end

mongo-bson.gemspec

@@ -0,0 +1,23 @@
+require "lib/mongo_bson"
+
+Gem::Specification.new do |s|
+  s.name = 'mongo_bson'
+
+  s.version = Mongo::BSON::VERSION
+
+  s.platform = Gem::Platform::RUBY
+  s.summary = 'Ruby implementation of BSON'
+  s.description = 'A Ruby BSON implementation for MongoDB. For more information about Mongo, see http://www.mongodb.org. For more information on BSON, see http://www.bsonspec.org.'
+
+  s.require_paths = ['lib']
+
+  s.files  = ['Rakefile', 'mongo-bson.gemspec', 'LICENSE.txt']
+  s.files += ['lib/mongo_bson.rb'] + Dir['lib/mongo_bson/**/*.rb']
+  s.test_files = Dir['test/mongo_bson/*.rb']
+
+  s.has_rdoc = true
+
+  s.authors = ['Jim Menard', 'Mike Dirolf', 'Kyle Banker']
+  s.email = 'mongodb-dev@googlegroups.com'
+  s.homepage = 'http://www.mongodb.org'
+end