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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 "mongo/db/jsobj.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/query/projection.h"
#include "mongo/db/query/query_solution.h"
namespace mongo {
/**
* Methods used by several parts of the planning process.
*/
class QueryPlannerCommon {
public:
/**
* Does the tree rooted at 'root' have a node with matchType 'type'?
*
* If 'out' is not NULL, sets 'out' to the first node of type 'type' encountered.
*/
static bool hasNode(const MatchExpression* root,
MatchExpression::MatchType type,
const MatchExpression** out = nullptr) {
if (type == root->matchType()) {
if (nullptr != out) {
*out = root;
}
return true;
}
for (size_t i = 0; i < root->numChildren(); ++i) {
if (hasNode(root->getChild(i), type, out)) {
return true;
}
}
return false;
}
/**
* Assumes the provided BSONObj is of the form {field1: -+1, ..., field2: -+1}
* Returns a BSONObj with the values negated.
*/
static BSONObj reverseSortObj(const BSONObj& sortObj) {
BSONObjBuilder reverseBob;
BSONObjIterator it(sortObj);
while (it.more()) {
BSONElement elt = it.next();
reverseBob.append(elt.fieldName(), elt.numberInt() * -1);
}
return reverseBob.obj();
}
/**
* Traverses the tree rooted at 'node'. Tests scan directions recursively to see if they are
* equal to the given direction argument. Returns true if they are and false otherwise.
*/
static bool scanDirectionsEqual(QuerySolutionNode* node, int direction);
/**
* Traverses the tree rooted at 'node'. For every STAGE_IXSCAN encountered, reverse
* the scan direction and index bounds, unless reverseCollScans equals true, in which case
* STAGE_COLLSCAN is reversed as well.
*/
static void reverseScans(QuerySolutionNode* node, bool reverseCollScans = false);
/**
* Extracts all field names for the sortKey meta-projection and stores them in the returned
* array. Returns an empty array if there were no sortKey meta-projection specified in the
* given projection 'proj'. For example, given a projection {a:1, b: {$meta: "sortKey"},
* c: {$meta: "sortKey"}}, the returned vector will contain two elements ["b", "c"].
*/
static std::vector<FieldPath> extractSortKeyMetaFieldsFromProjection(
const projection_ast::Projection& proj);
};
} // namespace mongo
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