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/**
* Copyright (C) 2020-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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 <vector>
#include "mongo/db/field_ref.h"
namespace mongo {
/**
* This class represents a path which can be taken through a specific document. In addition to the
* path components, which are stored as a FieldRef, RuntimeUpdatePath also stores the "type" of
* each component, which can be either kFieldName or kArrayIndex. Non-numeric components are always
* of type kFieldName. Numeric components may either be field names (in the case of an object like
* {"123": "foo"}) or array indexes.
*
* Unlike other path representations in our codebase, RuntimeUpdatePath is tied to a particular
* document. It does not represent a path that a user provides as part of an update.
*
* Example:
* Document: {a: {0: {b: ["foo", "bar"]}}}.
*
* The path to "bar" would be represented as "a.0.b.1" where "a" "0" and "b" are of type kFieldName
* while "1" is of type kArrayIndex.
*/
class RuntimeUpdatePath {
public:
enum ComponentType { kFieldName, kArrayIndex };
using ComponentTypeVector = std::vector<ComponentType>;
RuntimeUpdatePath() = default;
RuntimeUpdatePath(FieldRef fr, ComponentTypeVector types)
: _fieldRef(std::move(fr)), _types(std::move(types)) {
invariant(good());
}
/**
* Returns the underlying FieldRef.
*/
const FieldRef& fieldRef() const {
invariant(good());
return _fieldRef;
}
/**
* Returns the type array, which is guaranteed to be the same length as the backing FieldRef.
*/
const ComponentTypeVector& types() const {
invariant(good());
return _types;
}
bool empty() const {
invariant(good());
return _fieldRef.empty();
}
size_t size() const {
invariant(good());
return _fieldRef.numParts();
}
void append(StringData fieldName, ComponentType type) {
invariant(good());
_fieldRef.appendPart(fieldName);
_types.push_back(type);
}
void popBack() {
invariant(good());
invariant(_fieldRef.numParts() > 0);
_fieldRef.removeLastPart();
_types.pop_back();
}
private:
// Returns whether the RuntimeUpdatePath is in a valid state.
bool good() const {
return _fieldRef.numParts() == _types.size();
}
// There is an invariant that the number of components in field ref is equal to the number of
// types in _types.
FieldRef _fieldRef;
ComponentTypeVector _types;
};
/**
* RAII class for temporarily appending to a RuntimeUpdatePath.
*/
class RuntimeUpdatePathTempAppend {
public:
RuntimeUpdatePathTempAppend(RuntimeUpdatePath& typedFieldRef,
StringData part,
RuntimeUpdatePath::ComponentType type)
: _typedFieldRef(typedFieldRef) {
_typedFieldRef.append(part, type);
}
~RuntimeUpdatePathTempAppend() {
_typedFieldRef.popBack();
}
private:
RuntimeUpdatePath& _typedFieldRef;
};
} // namespace mongo
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