add get_expected_field, get_optional_field

lib/protocol_buffers/runtime/message.rb

@@ -426,6 +426,47 @@ def value_for_tag?(tag)
  @set_fields[tag] || false
  end
 
+ def get_expected_field(*nested_field_names)
+ if nested_field_names.size == 1
+ field_name = nested_field_names.first
+ field = self.class.field_for_name(field_name)
+ raise ArgumentError.new unless field
+ raise ArgumentError.new unless self.value_for_tag?(field.tag)
+ return self.value_for_tag(field.tag)
+ end
+ last_proto = nested_field_names[0..-2].inject(self) do |sub_proto, ifield_name|
+ sub_field = sub_proto.class.field_for_name(ifield_name)
+ raise ArgumentError.new unless sub_field
+ raise ArgumentError.new unless sub_field.is_a?(ProtocolBuffers::Field::MessageField)
+ raise ArgumentError.new unless sub_proto.value_for_tag?(sub_field.tag)
+ sub_proto.value_for_tag(sub_field.tag)
+ end
+ last_field_name = nested_field_names.last
+ last_field = last_proto.class.field_for_name(last_field_name)
+ raise ArgumentError.new unless last_field
+ raise ArgumentError.new unless last_proto.value_for_tag?(last_field.tag)
+ last_proto.value_for_tag(last_field.tag)
+ end
+
+ def get_optional_field(*nested_field_names)
+ if nested_field_names.size == 1
+ field_name = nested_field_names.first
+ field = self.class.field_for_name(field_name)
+ raise ArgumentError.new unless field
+ return self.value_for_tag?(field.tag) ? self.value_for_tag(field.tag) : nil
+ end
+ last_proto = nested_field_names[0..-2].inject(self) do |sub_proto, ifield_name|
+ sub_field = sub_proto.class.field_for_name(ifield_name)
+ raise ArgumentError.new unless sub_field
+ raise ArgumentError.new unless sub_field.is_a?(ProtocolBuffers::Field::MessageField)
+ return nil unless sub_proto.value_for_tag?(sub_field.tag)
+ sub_proto.value_for_tag(sub_field.tag)
+ end
+ last_field_name = nested_field_names.last
+ last_field = last_proto.class.field_for_name(last_field_name)
+ last_proto.value_for_tag?(last_field.tag) ? last_proto.value_for_tag(last_field.tag) : nil
+ end
+
  def inspect
  ret = ProtocolBuffers.bin_sio
  ret << "#<#{self.class.name}"

spec/message_spec.rb

@@ -116,4 +116,26 @@
 
  c.value_for_tag?(1).should == true
  end
+
+ it "correctly handles get_expected_field" do
+ f = Featureful::A.new
+ f.i3 = 4
+ f.sub3.subsub1.subsub_payload = "sub3subsubpayload"
+
+ f.get_expected_field(:sub3, :subsub1, :subsub_payload).should == "sub3subsubpayload"
+ f.get_expected_field(:i3).should == 4
+ proc { f.get_expected_field(:i2) }.should raise_error(ArgumentError)
+ proc { f.get_expected_field(:sub2) }.should raise_error(ArgumentError)
+ end
+
+ it "correctly handles get_optional_field" do
+ f = Featureful::A.new
+ f.i3 = 4
+ f.sub3.subsub1.subsub_payload = "sub3subsubpayload"
+
+ f.get_optional_field(:sub3, :subsub1, :subsub_payload).should == "sub3subsubpayload"
+ f.get_optional_field(:i3).should == 4
+ f.get_optional_field(:i2).should == nil
+ f.get_optional_field(:sub2).should == nil
+ end
 end