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/**
* Copyright (C) 2021-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/pipeline/window_function/window_function_count.h"
#include "mongo/db/pipeline/window_function/window_function_sum.h"
namespace mongo::window_function {
boost::intrusive_ptr<window_function::Expression> parseCountWindowFunction(
BSONObj obj, const boost::optional<SortPattern>& sortBy, ExpressionContext* expCtx) {
// 'obj' should be something like '{$count: {}}, window: {...}}'.
boost::optional<StringData> accumulatorName;
WindowBounds bounds = WindowBounds::defaultBounds();
for (const auto& arg : obj) {
auto argName = arg.fieldNameStringData();
if (argName == Expression::kWindowArg) {
uassert(ErrorCodes::FailedToParse,
"'window' field must be an object",
arg.type() == BSONType::Object);
bounds = WindowBounds::parse(arg.embeddedObject(), sortBy, expCtx);
} else if (Expression::isFunction(argName)) {
uassert(ErrorCodes::FailedToParse,
"Cannot specify multiple functions in window function spec",
!accumulatorName);
uassert(ErrorCodes::FailedToParse,
"$count only accepts an empty object as input",
arg.type() == BSONType::Object && arg.Obj().isEmpty());
accumulatorName = argName;
} else {
uasserted(ErrorCodes::FailedToParse,
str::stream() << "Window function found an unknown argument: " << argName);
}
}
uassert(ErrorCodes::FailedToParse,
"Must specify a window function in output field",
accumulatorName);
// Returns an expression representing "{ $sum: 1, window: bounds }".
return make_intrusive<ExpressionRemovable<AccumulatorSum, WindowFunctionSum>>(
expCtx, "$sum", ExpressionConstant::create(expCtx, Value(1)), std::move(bounds));
}
} // namespace mongo::window_function
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