add op_desc.proto (#2736)

* add op_desc.proto

In Operator design, we need a proto message to describe an Operator.
Third-party language such as python can build this proto message and use
AddOp(const OpDesc& op_desc) of Paddle core to construct an Op in the
Network.

paddle/framework/CMakeLists.txt

@@ -8,3 +8,6 @@ cc_test(enforce_test SRCS enforce_test.cc)
 proto_library(attr_type SRCS attr_type.proto)
 proto_library(op_proto SRCS op_proto.proto DEPS attr_type)
 cc_test(op_proto_test SRCS op_proto_test.cc DEPS op_proto protobuf)
+
+proto_library(op_desc SRCS op_desc.proto DEPS attr_type)
+cc_test(op_desc_test SRCS op_desc_test.cc DEPS op_desc protobuf)

paddle/framework/op_desc.proto

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+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. */
+
+syntax="proto2";
+package paddle.framework;
+
+import "attr_type.proto";
+
+// AttrDesc is used to describe Attributes of an Operator. It contain's
+// name, type, and value of Attribute.
+//
+// e.g, for scale=3.0: name=scala, type=AttrType.FLOAT, value=3.0
+message AttrDesc {
+    required string name = 1;
+    required AttrType type = 2;
+    optional int32 i = 3;
+    optional float f = 4;
+    optional string s = 5;
+    repeated int32 ints = 6;
+    repeated float floats = 7;
+    repeated string strings = 8;
+};
+
+// Protocol Message to describe an Operator.
+//
+// In PaddlePaddle, Operator is used to do a certain computation such
+// as "add", "sub", "cosine", etc.
+//  (1) Operator needs to know the input and output variable names.
+//  (2) Some ops may have special attributes such as "scale" in "CosineOp".
+//
+// 3rd-party language can build this proto message and call
+// AddOp(const OpDesc& op_desc) of Paddle core to create an Operator.
+message OpDesc {
+    // input names of this Operator.
+    repeated string inputs = 1;
+
+    // output names of this Operator.
+    repeated string outputs = 2;
+
+    // type of this Operator, such as "add", "sub", "fc".
+    required string type = 3;
+
+    // Attributes of this Operator. e.g., scale=3.0 in cosine op.
+    repeated AttrDesc attrs = 4;
+};
\ No newline at end of file

paddle/framework/op_desc_test.cc

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+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. */
+
+#include <gtest/gtest.h>
+#include <paddle/framework/op_desc.pb.h>
+
+TEST(OpDesc, Create) {
+  paddle::framework::OpDesc op_desc;
+  op_desc.set_type("add");
+  op_desc.add_inputs("X");
+  op_desc.add_inputs("Y");
+  op_desc.add_outputs("Z");
+
+  auto attr = op_desc.mutable_attrs()->Add();
+  attr->set_type(paddle::framework::AttrType::FLOAT);
+  attr->set_f(3.14);
+
+  // required field name is not set, so IsInitialized should be false.
+  ASSERT_FALSE(op_desc.IsInitialized());
+
+  attr->set_name("add");
+  // after all required fields are set, IsInitialized should be true now.
+  ASSERT_TRUE(op_desc.IsInitialized());
+}
\ No newline at end of file