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/**
* Copyright (C) 2018-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 <set>
#include <vector>
#include "mongo/base/owned_pointer_vector.h"
#include "mongo/base/status.h"
#include "mongo/db/field_ref.h"
namespace mongo {
/**
* A FieldRefSet holds a number of unique FieldRefs - a set of dotted paths into a document.
*
* The FieldRefSet provides helpful functions for efficiently finding conflicts between field
* ref paths - field ref paths conflict if they are equal to each other or if one is a prefix.
* To maintain a FieldRefSet of non-conflicting paths, always use the insert method which
* returns conflicting FieldRefs.
*
* FieldRefSets do not own the FieldRef paths they contain.
*/
class FieldRefSet {
FieldRefSet(const FieldRefSet&) = delete;
FieldRefSet& operator=(const FieldRefSet&) = delete;
struct FieldRefPtrLessThan {
bool operator()(const FieldRef* lhs, const FieldRef* rhs) const;
};
typedef std::set<const FieldRef*, FieldRefPtrLessThan> FieldSet;
public:
using iterator = FieldSet::iterator;
using const_iterator = FieldSet::const_iterator;
FieldRefSet();
FieldRefSet(const std::vector<FieldRef*>& paths);
/** Returns 'true' if the set is empty */
bool empty() const {
return _fieldSet.empty();
}
inline const_iterator begin() const {
return _fieldSet.begin();
}
inline const_iterator end() const {
return _fieldSet.end();
}
/**
* Returns true if the path does not already exist in the set, false otherwise.
*
* Note that *no* conflict resolution occurs - any path can be inserted into a set.
*/
inline bool insert(const FieldRef* path) {
return _fieldSet.insert(path).second;
}
/**
* Returns true if the field 'toInsert' can be added in the set without
* conflicts. Otherwise returns false and fill in '*conflict' with the field 'toInsert'
* clashed with.
*
* There is no ownership transfer of 'toInsert'. The caller is responsible for
* maintaining it alive for as long as the FieldRefSet is so. By the same token
* 'conflict' can only be referred to while the FieldRefSet can.
*/
bool insert(const FieldRef* toInsert, const FieldRef** conflict);
/**
* Fills the set with the supplied FieldRef*s
*
* Note that *no* conflict resolution occurs here.
*/
void fillFrom(const std::vector<FieldRef*>& fields);
/**
* Replace any existing conflicting FieldRef with the shortest (closest to root) one.
*/
void keepShortest(const FieldRef* toInsert);
/**
* Find all inserted fields which conflict with the FieldRef 'toCheck' by the semantics
* of 'insert', and add those fields to the 'conflicts' set.
*
* Return true if conflicts were found.
*/
bool findConflicts(const FieldRef* toCheck, FieldRefSet* conflicts) const;
void clear() {
_fieldSet.clear();
}
void erase(const FieldRef* item) {
_fieldSet.erase(item);
}
/**
* A debug/log-able string
*/
const std::string toString() const;
private:
// A set of field_ref pointers, none of which is owned here.
FieldSet _fieldSet;
};
/**
* A wrapper class for FieldRefSet which owns the storage of the underlying FieldRef objects.
*/
class FieldRefSetWithStorage {
public:
/**
* Inserts the given FieldRef into the set. In the case of a conflict with an existing element,
* only the shortest path is kept in the set.
*/
void keepShortest(const FieldRef& toInsert) {
const FieldRef* inserted = &(*_ownedFieldRefs.insert(toInsert).first);
_fieldRefSet.keepShortest(inserted);
}
std::vector<std::string> serialize() const {
std::vector<std::string> ret;
for (const auto fieldRef : _fieldRefSet) {
ret.push_back(fieldRef->dottedField().toString());
}
return ret;
}
bool empty() const {
return _fieldRefSet.empty();
}
void clear() {
_ownedFieldRefs.clear();
_fieldRefSet.clear();
}
std::string toString() const {
return _fieldRefSet.toString();
}
private:
// Holds the storage for FieldRef's inserted into the set. This may become out of sync with
// '_fieldRefSet' since we don't attempt to remove conflicts from the backing set, which can
// leave '_ownedFieldRefs' holding storage for a superset of the field refs that are actually
// contained in '_fieldRefSet'.
std::set<FieldRef> _ownedFieldRefs;
FieldRefSet _fieldRefSet;
};
} // namespace mongo
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