text: /**
   *    Copyright (C) 2019-present MongoDB, Inc.
   *
   *    This program is free software: you can redistribute it and/or modify
   *    it under the terms of the Server Side Public License, version 1,
   *    as published by MongoDB, Inc.
   *
   *    This program is distributed in the hope that it will be useful,
   *    but WITHOUT ANY WARRANTY; without even the implied warranty of
   *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *    Server Side Public License for more details.
   *
   *    You should have received a copy of the Server Side Public License
   *    along with this program. If not, see
   *    <http://www.mongodb.com/licensing/server-side-public-license>.
   *
   *    As a special exception, the copyright holders give permission to link the
   *    code of portions of this program with the OpenSSL library under certain
   *    conditions as described in each individual source file and distribute
   *    linked combinations including the program with the OpenSSL library. You
   *    must comply with the Server Side Public License in all respects for
   *    all of the code used other than as permitted herein. If you modify file(s)
   *    with this exception, you may extend this exception to your version of the
   *    file(s), but you are not obligated to do so. If you do not wish to do so,
   *    delete this exception statement from your version. If you delete this
   *    exception statement from all source files in the program, then also delete
   *    it in the license file.
   */
  
  #pragma once
  
  #include "mongo/db/exec/sbe/stages/stages.h"
  #include "mongo/db/exec/sbe/values/bson.h"
  
  namespace mongo {
  namespace sbe {
  /**
   * Scans a buffer of contiguous BSON documents, with the start of the buffer indicated by
   * 'bsonBegin' and the end indicated by 'bsonEnd'. The resulting BSON documents are placed into the
   * given 'recordSlot', if provided.
   *
   * The caller can also optionally provide a vector of top-level field names, 'fields', to extract
   * from each BSON object. The resulting values are placed into the slots indicated by the 'vars'
   * slot vector each time this stage advances. The provided 'fields' and 'vars' vectors must be of
   * equal length.
   */
  class BSONScanStage final : public PlanStage {
  public:
      BSONScanStage(const char* bsonBegin,
                    const char* bsonEnd,
                    boost::optional<value::SlotId> recordSlot,
                    std::vector<std::string> fields,
                    value::SlotVector vars,
                    PlanNodeId planNodeId);
  
      std::unique_ptr<PlanStage> clone() const final;
  
      void prepare(CompileCtx& ctx) final;
      value::SlotAccessor* getAccessor(CompileCtx& ctx, value::SlotId slot) final;
      void open(bool reOpen) final;
      PlanState getNext() final;
      void close() final;
  
      std::unique_ptr<PlanStageStats> getStats(bool includeDebugInfo) const final;
      const SpecificStats* getSpecificStats() const final;
  
      std::vector<DebugPrinter::Block> debugPrint() const final;
      size_t estimateCompileTimeSize() const final;
  
  private:
      const char* const _bsonBegin;
      const char* const _bsonEnd;
  
      const boost::optional<value::SlotId> _recordSlot;
      const std::vector<std::string> _fields;
      const value::SlotVector _vars;
  
      std::unique_ptr<value::ViewOfValueAccessor> _recordAccessor;
  
      value::FieldViewAccessorMap _fieldAccessors;
      value::SlotAccessorMap _varAccessors;
  
      const char* _bsonCurrent;
  
      ScanStats _specificStats;
  };
  }  // namespace sbe
  }  // namespace mongo
  