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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/db/matcher/expression.h"
#include "mongo/bson/bsonmisc.h"
#include "mongo/bson/bsonobj.h"
namespace mongo {
/**
* Enabling the disableMatchExpressionOptimization fail point will stop match expressions from
* being optimized.
*/
MONGO_FAIL_POINT_DEFINE(disableMatchExpressionOptimization);
namespace {
/**
* Comparator for MatchExpression nodes. Returns an integer less than, equal to, or greater
* than zero if 'lhs' is less than, equal to, or greater than 'rhs', respectively.
*
* Sorts by:
* 1) operator type (MatchExpression::MatchType)
* 2) path name (MatchExpression::path())
* 3) sort order of children
* 4) number of children (MatchExpression::numChildren())
*
* The third item is needed to ensure that match expression trees which should have the same
* cache key always sort the same way. If you're wondering when the tuple (operator type, path
* name) could ever be equal, consider this query:
*
* {$and:[{$or:[{a:1},{a:2}]},{$or:[{a:1},{b:2}]}]}
*
* The two OR nodes would compare as equal in this case were it not for tuple item #3 (sort
* order of children).
*/
int matchExpressionComparator(const MatchExpression* lhs, const MatchExpression* rhs) {
MatchExpression::MatchType lhsMatchType = lhs->matchType();
MatchExpression::MatchType rhsMatchType = rhs->matchType();
if (lhsMatchType != rhsMatchType) {
return lhsMatchType < rhsMatchType ? -1 : 1;
}
StringData lhsPath = lhs->path();
StringData rhsPath = rhs->path();
int pathsCompare = lhsPath.compare(rhsPath);
if (pathsCompare != 0) {
return pathsCompare;
}
const size_t numChildren = std::min(lhs->numChildren(), rhs->numChildren());
for (size_t childIdx = 0; childIdx < numChildren; ++childIdx) {
int childCompare =
matchExpressionComparator(lhs->getChild(childIdx), rhs->getChild(childIdx));
if (childCompare != 0) {
return childCompare;
}
}
if (lhs->numChildren() != rhs->numChildren()) {
return lhs->numChildren() < rhs->numChildren() ? -1 : 1;
}
// They're equal!
return 0;
}
bool matchExpressionLessThan(const MatchExpression* lhs, const MatchExpression* rhs) {
return matchExpressionComparator(lhs, rhs) < 0;
}
} // namespace
MatchExpression::MatchExpression(MatchType type, clonable_ptr<ErrorAnnotation> annotation)
: _errorAnnotation(std::move(annotation)), _matchType(type) {}
// static
void MatchExpression::sortTree(MatchExpression* tree) {
for (size_t i = 0; i < tree->numChildren(); ++i) {
sortTree(tree->getChild(i));
}
if (auto&& children = tree->getChildVector()) {
std::stable_sort(children->begin(), children->end(), matchExpressionLessThan);
}
}
std::string MatchExpression::toString() const {
return serialize().toString();
}
std::string MatchExpression::debugString() const {
StringBuilder builder;
debugString(builder, 0);
return builder.str();
}
void MatchExpression::_debugAddSpace(StringBuilder& debug, int indentationLevel) const {
for (int i = 0; i < indentationLevel; i++)
debug << " ";
}
bool MatchExpression::matchesBSON(const BSONObj& doc, MatchDetails* details) const {
BSONMatchableDocument mydoc(doc);
return matches(&mydoc, details);
}
bool MatchExpression::matchesBSONElement(BSONElement elem, MatchDetails* details) const {
BSONElementViewMatchableDocument matchableDoc(elem);
return matches(&matchableDoc, details);
}
void MatchExpression::setCollator(const CollatorInterface* collator) {
for (size_t i = 0; i < numChildren(); ++i) {
getChild(i)->setCollator(collator);
}
_doSetCollator(collator);
}
void MatchExpression::addDependencies(DepsTracker* deps) const {
for (size_t i = 0; i < numChildren(); ++i) {
// Don't recurse through MatchExpression nodes which require an entire array or entire
// subobject for matching.
const auto type = matchType();
switch (type) {
case MatchExpression::ELEM_MATCH_VALUE:
case MatchExpression::ELEM_MATCH_OBJECT:
case MatchExpression::INTERNAL_SCHEMA_OBJECT_MATCH:
continue;
default:
getChild(i)->addDependencies(deps);
}
}
_doAddDependencies(deps);
}
} // namespace mongo
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