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/**
* Copyright (C) 2019-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/query/sort_pattern.h"
namespace mongo {
SortPattern::SortPattern(const BSONObj& obj,
const boost::intrusive_ptr<ExpressionContext>& pExpCtx) {
for (auto&& keyField : obj) {
auto fieldName = keyField.fieldNameStringData();
SortPatternPart patternPart;
if (keyField.type() == Object) {
BSONObj metaDoc = keyField.Obj();
// this restriction is due to needing to figure out sort direction
uassert(17312,
"$meta is the only expression supported by $sort right now",
metaDoc.firstElement().fieldNameStringData() == "$meta");
uassert(ErrorCodes::FailedToParse,
"Cannot have additional keys in a $meta sort specification",
metaDoc.nFields() == 1);
VariablesParseState vps = pExpCtx->variablesParseState;
BSONElement metaElem = metaDoc.firstElement();
if (metaElem.valueStringDataSafe() == "textScore"_sd) {
// Valid meta sort. Just fall through.
} else if (metaElem.valueStringDataSafe() == "randVal"_sd) {
// Valid meta sort. Just fall through.
} else if (metaElem.valueStringDataSafe() == "searchScore"_sd) {
uasserted(31218, "$meta sort by 'searchScore' metadata is not supported");
} else if (metaElem.valueStringDataSafe() == "searchHighlights"_sd) {
uasserted(31219, "$meta sort by 'searchHighlights' metadata is not supported");
} else {
uasserted(31138, str::stream() << "Illegal $meta sort: " << metaElem);
}
patternPart.expression =
static_cast<ExpressionMeta*>(ExpressionMeta::parse(pExpCtx, metaElem, vps).get());
// If sorting by textScore, sort highest scores first. If sorting by randVal, order
// doesn't matter, so just always use descending.
patternPart.isAscending = false;
_sortPattern.push_back(std::move(patternPart));
continue;
}
uassert(15974,
str::stream() << "Illegal key in $sort specification: " << keyField,
keyField.isNumber());
int sortOrder = keyField.numberInt();
uassert(15975,
"$sort key ordering must be 1 (for ascending) or -1 (for descending)",
((sortOrder == 1) || (sortOrder == -1)));
patternPart.fieldPath = FieldPath{fieldName};
patternPart.isAscending = (sortOrder > 0);
_paths.insert(patternPart.fieldPath->fullPath());
_sortPattern.push_back(std::move(patternPart));
}
}
Document SortPattern::serialize(SortKeySerialization serializationMode) const {
MutableDocument keyObj;
const size_t n = _sortPattern.size();
for (size_t i = 0; i < n; ++i) {
if (_sortPattern[i].fieldPath) {
// Append a named integer based on whether the sort is ascending/descending.
keyObj.setField(_sortPattern[i].fieldPath->fullPath(),
Value(_sortPattern[i].isAscending ? 1 : -1));
} else {
// Sorting by an expression, use a made up field name.
auto computedFieldName = std::string(str::stream() << "$computed" << i);
switch (serializationMode) {
case SortKeySerialization::kForExplain:
case SortKeySerialization::kForPipelineSerialization: {
const bool isExplain = (serializationMode == SortKeySerialization::kForExplain);
keyObj[computedFieldName] = _sortPattern[i].expression->serialize(isExplain);
break;
}
case SortKeySerialization::kForSortKeyMerging: {
// We need to be able to tell which direction the sort is. Expression sorts are
// always descending.
keyObj[computedFieldName] = Value(-1);
break;
}
}
}
}
return keyObj.freeze();
}
} // namespace mongo
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