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/**
* 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/>.
*/
#pragma once
#include <boost/scoped_ptr.hpp>
#include <string>
#include "mongo/base/disallow_copying.h"
#include "mongo/bson/mutable/element.h"
#include "mongo/db/field_ref.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/ops/modifier_interface.h"
namespace mongo {
class LogBuilder;
class ModifierUnset : public ModifierInterface {
MONGO_DISALLOW_COPYING(ModifierUnset);
public:
ModifierUnset();
//
// Modifier interface implementation
//
virtual ~ModifierUnset();
/**
* A 'modExpr' is a BSONElement {<fieldname>: <value>} coming from a $set mod such as
* {$unset: {<fieldname: <value>}}. init() extracts the field name and the value to be
* assigned to it from 'modExpr'. It returns OK if successful or a status describing
* the error.
*/
virtual Status init(const BSONElement& modExpr, const Options& opts);
/**
* Locates the field to be removed under the 'root' element, if it exist, and fills in
* 'execInfo' accordingly. Return OK if successful or a status describing the error.
*/
virtual Status prepare(mutablebson::Element root,
const StringData& matchedField,
ExecInfo* execInfo);
/**
* Removes the found element from the document. If such element was inside an array,
* removal means setting that array position to 'null'.
*/
virtual Status apply() const;
/**
* Adds the exact $unset mod to the log.
*/
virtual Status log(LogBuilder* logBuilder) const;
private:
// 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;
// Element of the $set expression.
BSONElement _val;
// The instance of the field in the provided doc. This state is valid after a
// prepare() was issued and until a log() is issued. The document this mod is
// being prepared against must be live throughout all the calls.
struct PreparedState;
scoped_ptr<PreparedState> _preparedState;
};
} // namespace mongo
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