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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 <limits>
#include <string>
#include <vector>
#include "mongo/base/string_data.h"
#include "mongo/bson/bson_depth.h"
#include "mongo/db/exec/document_value/document_internal.h"
#include "mongo/util/assert_util.h"
namespace mongo {
/**
* Utility class which represents a field path with nested paths separated by dots.
*/
class FieldPath {
public:
/**
* Throws a AssertionException if a field name does not pass validation.
*/
static void uassertValidFieldName(StringData fieldName);
/**
* Concatenates 'prefix' and 'suffix' using dotted path notation. 'prefix' is allowed to be
* empty.
*/
static std::string getFullyQualifiedPath(StringData prefix, StringData suffix);
/**
* Returns the substring of 'path' until the first '.', or the entire string if there is no '.'.
*/
static StringData extractFirstFieldFromDottedPath(StringData path) {
return path.substr(0, path.find('.'));
}
/**
* Throws a AssertionException if the string is empty or if any of the field names fail
* validation.
*
* Field names are validated using uassertValidFieldName().
*/
/* implicit */ FieldPath(std::string inputPath, bool precomputeHashes = false);
/* implicit */ FieldPath(StringData inputPath, bool precomputeHashes = false)
: FieldPath(inputPath.toString(), precomputeHashes) {}
/* implicit */ FieldPath(const char* inputPath, bool precomputeHashes = false)
: FieldPath(std::string(inputPath), precomputeHashes) {}
/**
* Returns the number of path elements in the field path.
*/
size_t getPathLength() const {
return _fieldPathDotPosition.size() - 1;
}
/**
* Get the subpath including path elements [0, n].
*/
StringData getSubpath(size_t n) const {
invariant(n + 1 < _fieldPathDotPosition.size());
return StringData(_fieldPath.c_str(), _fieldPathDotPosition[n + 1]);
}
/**
* Return the first path component.
*/
StringData front() const {
return getFieldName(0);
}
/**
* Return the last path component.
*/
StringData back() const {
return getFieldName(getPathLength() - 1);
}
/**
* Return the ith field name from this path using zero-based indexes.
*/
StringData getFieldName(size_t i) const {
dassert(i < getPathLength());
const auto begin = _fieldPathDotPosition[i] + 1;
const auto end = _fieldPathDotPosition[i + 1];
return StringData(&_fieldPath[begin], end - begin);
}
/**
* Return the ith field name from this path using zero-based indexes, with pre-computed hash.
*/
HashedFieldName getFieldNameHashed(size_t i) const {
dassert(i < getPathLength());
invariant(_fieldHash[i] != kHashUninitialized);
return HashedFieldName{getFieldName(i), _fieldHash[i]};
}
/**
* Returns the full path, not including the prefix 'FieldPath::prefix'.
*/
const std::string& fullPath() const {
return _fieldPath;
}
/**
* Returns the full path, including the prefix 'FieldPath::prefix'.
*/
std::string fullPathWithPrefix() const {
return prefix + _fieldPath;
}
/**
* A FieldPath like this but missing the first element (useful for recursion).
* Precondition getPathLength() > 1.
*/
FieldPath tail() const {
massert(16409, "FieldPath::tail() called on single element path", getPathLength() > 1);
return {_fieldPath.substr(_fieldPathDotPosition[1] + 1)};
}
/**
* Returns a FieldPath like this, but missing the last element.
*/
FieldPath withoutLastElement() const {
return FieldPath(getSubpath(getPathLength() - 2));
}
FieldPath concat(const FieldPath& tail) const;
private:
FieldPath(std::string string, std::vector<size_t> dots, std::vector<size_t> hashes)
: _fieldPath(std::move(string)),
_fieldPathDotPosition(std::move(dots)),
_fieldHash(std::move(hashes)) {
uassert(ErrorCodes::Overflow,
"FieldPath is too long",
_fieldPathDotPosition.size() <= BSONDepth::getMaxAllowableDepth());
}
static const char prefix = '$';
// Contains the full field path, with each field delimited by a '.' character.
std::string _fieldPath;
// Contains the position of field delimiter dots in '_fieldPath'. The first element contains
// string::npos (which evaluates to -1) and the last contains _fieldPath.size() to facilitate
// lookup.
std::vector<size_t> _fieldPathDotPosition;
// Contains the hash value for the field names if it was requested when creating this path.
// Otherwise all elements are set to 'kHashUninitialized'.
std::vector<size_t> _fieldHash;
static constexpr std::size_t kHashUninitialized = std::numeric_limits<std::size_t>::max();
};
inline bool operator<(const FieldPath& lhs, const FieldPath& rhs) {
return lhs.fullPath() < rhs.fullPath();
}
inline bool operator==(const FieldPath& lhs, const FieldPath& rhs) {
return lhs.fullPath() == rhs.fullPath();
}
} // namespace mongo
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