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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.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/field_ref_set.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/str.h"
namespace mongo {
using std::vector;
using std::string;
namespace {
// For legacy purposes, we must handle empty fieldnames, which FieldRef clearly
// prohibits. It is preferrable to have FieldRef keep that constraint and relax it here
// -- stricly in update code. The rationale is that, if we want to ban data with no
// field names, we must allow that data to be updated.
StringData safeFirstPart(const FieldRef* fieldRef) {
if (fieldRef->numParts() == 0) {
return StringData();
} else {
return fieldRef->getPart(0);
}
}
}
bool FieldRefSet::FieldRefPtrLessThan::operator()(const FieldRef* l, const FieldRef* r) const {
return *l < *r;
}
FieldRefSet::FieldRefSet() {}
FieldRefSet::FieldRefSet(const vector<FieldRef*>& paths) {
fillFrom(paths);
}
bool FieldRefSet::findConflicts(const FieldRef* toCheck, FieldRefSet* conflicts) const {
bool foundConflict = false;
// If the set is empty, there is no work to do.
if (_fieldSet.empty())
return foundConflict;
StringData prefixStr = safeFirstPart(toCheck);
FieldRef prefixField(prefixStr);
FieldSet::iterator it = _fieldSet.lower_bound(&prefixField);
// Now, iterate over all the present fields in the set that have the same prefix.
while (it != _fieldSet.end() && safeFirstPart(*it) == prefixStr) {
size_t common = (*it)->commonPrefixSize(*toCheck);
if ((*it)->numParts() == common || toCheck->numParts() == common) {
if (!conflicts)
return true;
conflicts->_fieldSet.insert(*it);
foundConflict = true;
}
++it;
}
return foundConflict;
}
void FieldRefSet::keepShortest(const FieldRef* toInsert) {
const FieldRef* conflict;
if (!insert(toInsert, &conflict) && (toInsert->numParts() < (conflict->numParts()))) {
_fieldSet.erase(conflict);
keepShortest(toInsert);
}
}
void FieldRefSet::fillFrom(const std::vector<FieldRef*>& fields) {
dassert(_fieldSet.empty());
_fieldSet.insert(fields.begin(), fields.end());
}
bool FieldRefSet::insert(const FieldRef* toInsert, const FieldRef** conflict) {
// We can determine if two fields conflict by checking their common prefix.
//
// If each field is exactly of the size of the common prefix, this means the fields are
// the same. If one of the fields is greater than the common prefix and the other
// isn't, the latter is a prefix of the former. And vice-versa.
//
// Example:
//
// inserted > | a a.c
// exiting v | (0) (+1)
// ----------------|------------------------
// a (0) | equal prefix <
// a.b (+1) | prefix ^ *
//
// * Disjoint sub-trees
// At each insertion, we only need to bother checking the fields in the set that have
// at least some common prefix with the 'toInsert' field.
StringData prefixStr = safeFirstPart(toInsert);
FieldRef prefixField(prefixStr);
FieldSet::iterator it = _fieldSet.lower_bound(&prefixField);
// Now, iterate over all the present fields in the set that have the same prefix.
while (it != _fieldSet.end() && safeFirstPart(*it) == prefixStr) {
size_t common = (*it)->commonPrefixSize(*toInsert);
if ((*it)->numParts() == common || toInsert->numParts() == common) {
*conflict = *it;
return false;
}
++it;
}
_fieldSet.insert(it, toInsert);
*conflict = NULL;
return true;
}
const std::string FieldRefSet::toString() const {
str::stream ss;
ss << "{";
const auto last = _fieldSet.rbegin();
for (auto path : _fieldSet) {
ss << path->dottedField();
if (path != *last)
ss << ", ";
}
ss << "}";
return ss;
}
} // namespace mongo
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