query_optimizer/OptimizerContext.hpp

/**
 * 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.
 **/

#ifndef QUICKSTEP_QUERY_OPTIMIZER_OPTIMIZER_CONTEXT_HPP_
#define QUICKSTEP_QUERY_OPTIMIZER_OPTIMIZER_CONTEXT_HPP_

#include "query_optimizer/expressions/ExprId.hpp"
#include "utility/Macros.hpp"

namespace quickstep {

namespace optimizer {

/** \addtogroup QueryOptimizer
 *  @{
 */

/**
 * @brief Stores stateful or common info used throughout the optimization of a
 *        query.
 */
class OptimizerContext {
 public:
  static const char *kInternalTemporaryRelationNamePrefix;

  /**
   * @brief Constructor.
   */
  OptimizerContext()
      : current_expr_id_(-1),
        has_nested_queries_(false),
        is_catalog_changed_(false) {}

  /**
   * @brief Destructor.
   */
  ~OptimizerContext() {}

  /**
   * @brief Gets the next ExprId.
   *
   * @return A new ExprId.
   */
  expressions::ExprId nextExprId() {
    return ++current_expr_id_;
  }

  /**
   * @brief Indicate that the query has a nested subquery.
   */
  void set_has_nested_queries() {
    has_nested_queries_ = true;
  }

  /**
   * @return True if the query has a nested subquery.
   */
  bool has_nested_queries() const {
    return has_nested_queries_;
  }

  /**
   * @brief Sets <is_catalog_changed_> to be true to indicate the query will
   *        modify the catalog permanently.
   */
  void set_is_catalog_changed() { is_catalog_changed_ = true; }

  /**
   * @return True if the catalog will be permanently changed after the query.
   */
  bool is_catalog_changed() const { return is_catalog_changed_; }

 private:
  expressions::ExprId current_expr_id_;

  bool has_nested_queries_;

  bool is_catalog_changed_;

  DISALLOW_COPY_AND_ASSIGN(OptimizerContext);
};

/** @} */

}  // namespace optimizer
}  // namespace quickstep

#endif /* QUICKSTEP_QUERY_OPTIMIZER_OPTIMIZER_CONTEXT_HPP_ */