!15579 Add Switch Actor.

From: @gaoyong10
Reviewed-by: @wilfchen,@cristoval,@wilfchen
Signed-off-by: @wilfchen

mindspore/core/mindrt/include/actor/switch_actor.h

@@ -0,0 +1,44 @@
+/**
+ * Copyright 2021 Huawei Technologies Co., Ltd
+ *
+ * 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.
+ */
+
+#ifndef MINDSPORE_CORE_MINDRT_INCLUDE_ACTOR_SWITCH_ACTOR_H
+#define MINDSPORE_CORE_MINDRT_INCLUDE_ACTOR_SWITCH_ACTOR_H
+
+#include <string>
+#include <vector>
+#include <unordered_map>
+#include "actor/actor.h"
+#include "actor/op_actor.h"
+
+namespace mindspore {
+
+template <typename T>
+class SwitchActorBase : public OpActor<T> {
+ public:
+  explicit SwitchActorBase(std::string op_name) : ActorBase(op_name) {}
+  virtual ~SwitchActorBase() = default;
+
+  // The actor run when receive the input data.
+  void RunOpData(OpDataPtr<T> input_data, OpContext<T> *context = nullptr) override {}
+
+ protected:
+  // Different output branches according to the input.
+  std::vector<std::vector<OpArrowPtr>> output_branch_arrows_;
+};
+
+}  // namespace mindspore
+
+#endif  // MINDSPORE_CORE_MINDRT_INCLUDE_ACTOR_SWITCH_ACTOR_H