text: /**
   *    Copyright (C) 2014 MongoDB Inc.
   *
   *    This program is free software: you can redistribute it and/or  modify
   *    it under the terms of the GNU Affero General Public License, version 3,
   *    as published by the Free Software Foundation.
   *
   *    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
   *    GNU Affero General Public License for more details.
   *
   *    You should have received a copy of the GNU Affero General Public License
   *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *    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 GNU Affero General 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/base/disallow_copying.h"
  #include "mongo/base/status.h"
  #include "mongo/db/query/plan_executor.h"
  
  namespace mongo {
  
  class CanonicalQuery;
  class Database;
  class DeleteRequest;
  class OperationContext;
  
  /**
   * This class takes a pointer to a DeleteRequest, and converts that request into a parsed form
   * via the parseRequest() method. A ParsedDelete can then be used to retrieve a PlanExecutor
   * capable of executing the delete.
   *
   * It is invalid to request that the DeleteStage return the deleted document during a
   * multi-remove. It is also invalid to request that a ProjectionStage be applied to the
   * DeleteStage if the DeleteStage would not return the deleted document.
   *
   * A delete request is parsed to a CanonicalQuery, so this class is a thin, delete-specific
   * wrapper around canonicalization.
   *
   * No locks need to be held during parsing.
   */
  class ParsedDelete {
      MONGO_DISALLOW_COPYING(ParsedDelete);
  
  public:
      /**
       * Constructs a parsed delete.
       *
       * The object pointed to by "request" must stay in scope for the life of the constructed
       * ParsedDelete.
       */
      ParsedDelete(OperationContext* txn, const DeleteRequest* request);
  
      /**
       * Parses the delete request to a canonical query. On success, the parsed delete can be
       * used to create a PlanExecutor capable of executing this delete.
       */
      Status parseRequest();
  
      /**
       * As an optimization, we do not create a canonical query if the predicate is a simple
       * _id equality. This method can be used to force full parsing to a canonical query,
       * as a fallback if the idhack path is not available (e.g. no _id index).
       */
      Status parseQueryToCQ();
  
      /**
       * Get the raw request.
       */
      const DeleteRequest* getRequest() const;
  
      /**
       * Is this delete allowed to yield?
       */
      bool canYield() const;
  
      /**
       * Is this update supposed to be isolated?
       */
      bool isIsolated() const;
  
      /**
       * As an optimization, we don't create a canonical query for updates with simple _id
       * queries. Use this method to determine whether or not we actually parsed the query.
       */
      bool hasParsedQuery() const;
  
      /**
       * Releases ownership of the canonical query to the caller.
       */
      std::unique_ptr<CanonicalQuery> releaseParsedQuery();
  
  private:
      // Transactional context.  Not owned by us.
      OperationContext* _txn;
  
      // Unowned pointer to the request object that this executor will process.
      const DeleteRequest* const _request;
  
      // Parsed query object, or NULL if the query proves to be an id hack query.
      std::unique_ptr<CanonicalQuery> _canonicalQuery;
  };
  
  }  // namespace mongo
  