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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"
#include "mongo/db/ops/modifier_push_sorter.h"
namespace mongo {
class LogBuilder;
class ModifierPush : public ModifierInterface {
MONGO_DISALLOW_COPYING(ModifierPush);
public:
enum ModifierPushMode { PUSH_NORMAL, PUSH_ALL };
explicit ModifierPush(ModifierPushMode mode= PUSH_NORMAL);
//
// Modifier interface implementation
//
virtual ~ModifierPush();
/**
* A 'modExpr' here is a BSONElement {<fieldname>: <each clause>, <slice clause>, <sort
* clause>} coming from a $push mod such as {$set: {x: $each[{a:1}], $slice:3,
* $sort{b:1}}}. init() extracts and validates the field name and the clauses. It
* returns OK if successful or a status describing the error.
*
* There are currently a few restrictions concerning the clauses (but all can be
* lifted):
* + $slice can be negative only (ie, slicing from the recent end)
* + $sort requires $slice to be present
* + $sort can only sort objects (as opposed to basic types), so it only takes
* object as patterns
* + Because of the previous, $sort requires that the array being pushed to be made
* of objects
*/
virtual Status init(const BSONElement& modExpr, const Options& opts);
/**
* Locates the array to be pushed into in the 'root', if it exists, and fills in
* execInfo accordingly. Returns true if $push would succeed in 'root', otherwise
* return a status describing the error.
*
* Note that a $push is never in-place. The cost of checking if it is a no-op makes it
* so that we don't do such check either. As such, execInfo is always filled with
* 'false' for those two options.
*/
virtual Status prepare(mutablebson::Element root,
const StringData& matchedField,
ExecInfo* execInfo);
/**
* Pushes the array into the prepared position and "sort/slice"s the resulting array
* according to that call's instructions.
*/
virtual Status apply() const;
/**
* $push currently logs the entire resulting array as a $set.
*
* TODO Log a positional $set in the array, whenever possible.
*/
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;
// Clauses for the $push that are filled when the $each variation of the command is used.
bool _eachMode;
BSONElement _eachElem;
bool _slicePresent;
int64_t _slice;
bool _sortPresent;
PatternElementCmp _sort;
// Whether this mod is supposed to be parsed as a $pushAll.
const ModifierPushMode _pushMode;
// Simple (old style) push value when the $each variation of the command is not
// used. The _eachMode flag would be off if we're this mode.
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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