text: /**
   *    Copyright (C) 2013 10gen 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/bson/mutable/document.h"
  #include "mongo/db/field_ref.h"
  #include "mongo/db/ops/modifier_interface.h"
  
  namespace mongo {
  
  class CollatorInterface;
  class MatchExpression;
  
  class ModifierPull : public ModifierInterface {
      MONGO_DISALLOW_COPYING(ModifierPull);
  
  public:
      ModifierPull();
      virtual ~ModifierPull();
  
      /** Evaluates the array items to be removed and the match expression. */
      virtual Status init(const BSONElement& modExpr, const Options& opts, bool* positional = NULL);
  
      /** Decides which portion of the array items will be removed from the provided element */
      virtual Status prepare(mutablebson::Element root, StringData matchedField, ExecInfo* execInfo);
  
      /** Updates the Element used in prepare with the effects of the $pull operation. */
      virtual Status apply() const;
  
      /** Converts the effects of this $pull into one or more equivalent $unset operations. */
      virtual Status log(LogBuilder* logBuilder) const;
  
  private:
      bool isMatch(mutablebson::ConstElement element);
  
      // Access to each component of fieldName that's the target of this mod.
      FieldRef _fieldRef;
  
      // 0 or index for $-positional in _fieldRef.
      size_t _posDollar;
  
      // If we aren't using a matcher, we just keep modExpr as _exprElt and use that to match
      // with woCompare.
      BSONElement _exprElt;
  
      // If we are using a matcher, we need to keep around a BSONObj for it.
      BSONObj _exprObj;
  
      // If we are using the matcher, this is the match expression we built around _exprObj.
      std::unique_ptr<MatchExpression> _matchExpr;
      bool _matcherOnPrimitive;
  
      // The collator which must be used for matching strings. Null if we should use a simple binary
      // comparison.
      const CollatorInterface* _collator = nullptr;
  
      struct PreparedState;
      std::unique_ptr<PreparedState> _preparedState;
  };
  
  }  // namespace mongo
  