/**
 * Copyright (C) 2016 MongoDB Inc.
 *
 * This program is free software: you can redistribute it and/or  modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * 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
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * 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 GNU Affero General 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/pipeline/document_source_single_document_transformation.h"

namespace mongo {

/*
 * $replaceRoot takes an object containing only an expression in the newRoot field, and replaces
 * each incoming document with the result of evaluating that expression. Throws an error if the
 * given expression is not an object or if the expression evaluates to the "missing" Value. This
 * is implemented as an extension of DocumentSourceSingleDocumentTransformation.
 */
class DocumentSourceReplaceRoot final {
public:
    /**
     * Creates a new replaceRoot DocumentSource from the BSON specification of the $replaceRoot
     * stage.
     */
    static boost::intrusive_ptr<DocumentSource> createFromBson(
        BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& pExpCtx);

private:
    // It is illegal to construct a DocumentSourceReplaceRoot directly, use createFromBson()
    // instead.
    DocumentSourceReplaceRoot() = default;
};

}  // namespace mongo