Adds support for proto2 syntax for Ruby gem.

This change only adds basic proto2 support without advanced features
like extensions, custom options, maps, etc.

The protoc binary now generates ruby code for proto2 syntax.
However, for now, it is restricted to proto2 files without advanced features
like extensions, in which case it still errors out.

This change also modifies the DSL to add proto messages to the DescriptorPool.
There is a new DSL Builder#add_file to create a new FileDescriptor. With this,
the generated ruby DSL looks something like:

Google::Protobuf::DescriptorPool.generated_pool.build do
  add_file "test.proto" do
    add_message "foo" do
      optional :val, :int32, 1
    end
  end
end

1 files changed, 46 insertions, 2 deletions

diff --git a/ruby/tests/gc_test.rb b/ruby/tests/gc_test.rb
index f3470cca..55b96289 100644
--- a/ruby/tests/gc_test.rb
+++ b/ruby/tests/gc_test.rb
@@ -6,12 +6,13 @@ $LOAD_PATH.unshift(File.expand_path(File.dirname(__FILE__)))
 old_gc = GC.stress
 GC.stress = 0x01 | 0x04
 require 'generated_code_pb'
+require 'generated_code_proto2_pb'
 GC.stress = old_gc
 
 require 'test/unit'
 
 class GCTest < Test::Unit::TestCase
-  def get_msg
+  def get_msg_proto3
     A::B::C::TestMessage.new(
         :optional_int32 => 1,
         :optional_int64 => 1,
@@ -46,12 +47,55 @@ class GCTest < Test::Unit::TestCase
         :map_string_bool => {"a" => true},
     )
   end
+
+  def get_msg_proto2
+    A::B::Proto2::TestMessage.new(
+        :optional_int32 => 1,
+        :optional_int64 => 1,
+        :optional_uint32 => 1,
+        :optional_uint64 => 1,
+        :optional_bool => true,
+        :optional_double => 1.0,
+        :optional_float => 1.0,
+        :optional_string => "a",
+        :optional_bytes => "b",
+        :optional_enum => A::B::Proto2::TestEnum::A,
+        :optional_msg => A::B::Proto2::TestMessage.new(),
+        :repeated_int32 => [1],
+        :repeated_int64 => [1],
+        :repeated_uint32 => [1],
+        :repeated_uint64 => [1],
+        :repeated_bool => [true],
+        :repeated_double => [1.0],
+        :repeated_float => [1.0],
+        :repeated_string => ["a"],
+        :repeated_bytes => ["b"],
+        :repeated_enum => [A::B::Proto2::TestEnum::A],
+        :repeated_msg => [A::B::Proto2::TestMessage.new()],
+        :required_int32 => 1,
+        :required_int64 => 1,
+        :required_uint32 => 1,
+        :required_uint64 => 1,
+        :required_bool => true,
+        :required_double => 1.0,
+        :required_float => 1.0,
+        :required_string => "a",
+        :required_bytes => "b",
+        :required_enum => A::B::Proto2::TestEnum::A,
+        :required_msg => A::B::Proto2::TestMessage.new(),
+    )
+  end
+
   def test_generated_msg
     old_gc = GC.stress
     GC.stress = 0x01 | 0x04
-    from = get_msg
+    from = get_msg_proto3
     data = A::B::C::TestMessage.encode(from)
     to = A::B::C::TestMessage.decode(data)
+
+    from = get_msg_proto2
+    data = A::B::Proto2::TestMessage.encode(from)
+    to = A::B::Proto2::TestMessage.decode(data)
     GC.stress = old_gc
     puts "passed"
   end