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/**
* Copyright (C) 2017 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 <memory>
#include "mongo/bson/bsonelement.h"
#include "mongo/bson/mutable/element.h"
#include "mongo/db/field_ref_set.h"
#include "mongo/db/update/log_builder.h"
#include "mongo/db/update_index_data.h"
#include "mongo/util/assert_util.h"
namespace mongo {
class CollatorInterface;
class FieldRef;
/**
* Update modifier expressions are stored as a prefix tree of UpdateNodes, where two modifiers that
* share a field path prefix share a path prefix in the tree. The prefix tree is used to enforce
* that no update modifier's field path is a prefix of (or equal to) another update modifier's field
* path. The root of the UpdateNode tree is always an UpdateObjectNode. The leaves are always
* UpdateLeafNodes.
*
* Example: {$set: {'a.b': 5, c: 6}, $inc: {'a.c': 1}}
*
* UpdateObjectNode
* a / \ c
* UpdateObjectNode SetNode: _val = 6
* b / \ c
* SetNode: _val = 5 IncNode: _val = 1
*/
class UpdateNode {
public:
enum class Context { kAll, kInsertOnly };
enum class Type { Object, Array, Leaf, Replacement };
explicit UpdateNode(Type type, Context context = Context::kAll)
: context(context), type(type) {}
virtual ~UpdateNode() = default;
virtual std::unique_ptr<UpdateNode> clone() const = 0;
/**
* Set the collation on the node and all descendants. This is a noop if no leaf nodes require a
* collator. If setCollator() is called, it is required that the current collator of all leaf
* nodes is the simple collator (nullptr). The collator must outlive the modifier interface.
* This is used to override the collation after obtaining a collection lock if the update did
* not specify a collation and the collection has a non-simple default collation.
*/
virtual void setCollator(const CollatorInterface* collator) = 0;
/**
* The parameters required by UpdateNode::apply.
*/
struct ApplyParams {
ApplyParams(mutablebson::Element element, const FieldRefSet& immutablePaths)
: element(element), immutablePaths(immutablePaths) {}
// The element to update.
mutablebson::Element element;
// UpdateNode::apply uasserts if it modifies an immutable path.
const FieldRefSet& immutablePaths;
// The path taken through the UpdateNode tree beyond where the path existed in the document.
// For example, if the update is {$set: {'a.b.c': 5}}, and the document is {a: {}}, then at
// the leaf node, 'pathToCreate'="b.c".
std::shared_ptr<FieldRef> pathToCreate = std::make_shared<FieldRef>();
// The path through the root document to 'element', ending with the field name of 'element'.
// For example, if the update is {$set: {'a.b.c': 5}}, and the document is {a: {}}, then at
// the leaf node, 'pathTaken'="a".
std::shared_ptr<FieldRef> pathTaken = std::make_shared<FieldRef>();
// If there was a positional ($) element in the update expression, 'matchedField' is the
// index of the array element that caused the query to match the document.
StringData matchedField;
// True if the update is being applied to a document to be inserted. $setOnInsert behaves as
// a no-op when this flag is false.
bool insert = false;
// This is provided because some modifiers may ignore certain errors when the update is from
// replication.
bool fromReplication = false;
// If true, UpdateNode::apply ensures that modified elements do not violate depth or DBRef
// constraints.
bool validateForStorage = true;
// Used to determine whether indexes are affected.
const UpdateIndexData* indexData = nullptr;
// If provided, UpdateNode::apply will log the update here.
LogBuilder* logBuilder = nullptr;
};
/**
* The outputs of apply().
*/
struct ApplyResult {
static ApplyResult noopResult() {
ApplyResult applyResult;
applyResult.indexesAffected = false;
applyResult.noop = true;
return applyResult;
}
bool indexesAffected = true;
bool noop = false;
};
/**
* Applies the update node to 'applyParams.element', creating the fields in
* 'applyParams.pathToCreate' if required by the leaves (i.e. the leaves are not all $unset).
* Returns an ApplyResult specifying whether the operation was a no-op and whether indexes are
* affected.
*/
virtual ApplyResult apply(ApplyParams applyParams) const = 0;
/**
* Creates a new node by merging the contents of two input nodes. The semantics of the merge
* operation depend on the types of the input nodes. When the nodes have the same type, this
* function dispatches the merge to a createUpdateNodeByMerging implementation defined for that
* subtype. Throws AssertionException with a ConflictingUpdateOperators code when the types of
* the input nodes differ or when any of the child nodes fail to merge.
*/
static std::unique_ptr<UpdateNode> createUpdateNodeByMerging(const UpdateNode& leftNode,
const UpdateNode& rightNode,
FieldRef* pathTaken);
const Context context;
const Type type;
};
} // namespace mongo
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