text: /*
   * Copyright (c) 2018 Samsung Electronics Co., Ltd. All Rights Reserved
   *
   * 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 __NEST_EXPR_NODE_H__
  #define __NEST_EXPR_NODE_H__
  
  #include "nest/expr/Macro.h"
  #include "nest/expr/Forward.h"
  #include "nest/expr/Visitor.h"
  
  #include <stdexcept>
  
  namespace nest
  {
  namespace expr
  {
  
  struct Node
  {
    virtual ~Node() = default;
  
  #define EXPR(Tag)                                                                       \
    virtual const NEST_EXPR_CLASS_NAME(Tag) * NEST_EXPR_CAST_METHOD_NAME(Tag)(void) const \
    {                                                                                     \
      return nullptr;                                                                     \
    }
  #include "nest/expr/Node.def"
  #undef EXPR
  
    template <typename T> T accept(Visitor<T> *v)
    {
  #define EXPR(Tag)                                 \
    if (auto e = NEST_EXPR_CAST_METHOD_NAME(Tag)()) \
    {                                               \
      return v->visit(e);                           \
    }
  #include "nest/expr/Node.def"
  #undef EXPR
  
      throw std::runtime_error{"unreachable"};
    }
  
    template <typename T> T accept(Visitor<T> &v) { return accept(&v); }
  };
  
  } // namespace expr
  } // namespace nest
  
  #endif // __NEST_EXPR_NODE_H__
  