text: // Licensed to the Apache Software Foundation (ASF) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The ASF licenses this file
  // to you 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 "runtime/tuple_row.h"
  #include "util/runtime_profile.h"
  #include "exprs/expr_context.h"
  #include "exprs/expr.h"
  #include "common/object_pool.h"
  #include "common/status.h"
  #include "runtime/exec_env.h"
  #include "gen_cpp/internal_service.pb.h"
  #include "gen_cpp/PaloInternalService_types.h"
  
  namespace doris {
  
  class TFoldConstantParams;
  class TExpr;
  class TQueryGlobals;
  
  // This class used to fold constant expr from fe
  class FoldConstantMgr {
  public:
      FoldConstantMgr(ExecEnv* exec_env);
      // fold constant expr 
      Status fold_constant_expr(const TFoldConstantParams& params, PConstantExprResult* response);
      // init runtime_state and mem_tracker
      Status init(TQueryGlobals query_globals);
      // prepare expr
      Status prepare_and_open(ExprContext* ctx);
  
      std::string get_result(void* src, PrimitiveType slot_type);
  
  private:
      std::unique_ptr<RuntimeState> _runtime_state;
      std::shared_ptr<MemTracker> _mem_tracker;
      RuntimeProfile* _runtime_profile;
      std::unique_ptr<MemPool> _mem_pool;
      ExecEnv* _exec_env;
      ObjectPool _pool;
      static TUniqueId _dummy_id;
  };
  }
  
  