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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.
*/
#pragma once
#include "mongo/db/pipeline/expression.h"
#include "mongo/db/pipeline/javascript_execution.h"
namespace mongo {
/**
* This expression takes in a JavaScript function and a "this" reference, and returns an array of
* key/value objects which are the results of calling emit() from the provided JS function.
*/
class ExpressionInternalJsEmit final : public Expression {
public:
static constexpr auto kExpressionName = "$_internalJsEmit"_sd;
static boost::intrusive_ptr<Expression> parse(ExpressionContext* expCtx,
BSONElement expr,
const VariablesParseState& vps);
static boost::intrusive_ptr<ExpressionInternalJsEmit> create(
ExpressionContext* const expCtx,
boost::intrusive_ptr<Expression> thisRef,
std::string funcSourceString) {
return new ExpressionInternalJsEmit{expCtx, thisRef, std::move(funcSourceString)};
}
Value evaluate(const Document& root, Variables* variables) const final;
Value serialize(bool explain) const final;
void acceptVisitor(ExpressionMutableVisitor* visitor) final {
return visitor->visit(this);
}
void acceptVisitor(ExpressionConstVisitor* visitor) const final {
return visitor->visit(this);
}
// For a given invocation of the user-defined function, this struct holds the results of each
// call to emit(). Mark as mutable since it needs to be modified for each call to evaluate().
mutable struct EmitState {
void emit(Document&& doc) {
bytesUsed += doc.getApproximateSize();
uassert(31292,
str::stream() << "Size of emitted values exceeds the set size limit of "
<< byteLimit << " bytes",
bytesUsed < byteLimit);
emittedObjects.emplace_back(std::move(doc));
}
auto reset() {
emittedObjects.clear();
bytesUsed = 0;
}
std::vector<Value> emittedObjects;
int byteLimit;
int bytesUsed;
} _emitState;
private:
ExpressionInternalJsEmit(ExpressionContext* expCtx,
boost::intrusive_ptr<Expression> thisRef,
std::string funcSourceString);
const boost::intrusive_ptr<Expression>& _thisRef;
std::string _funcSource;
};
} // namespace mongo
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