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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.
*/
#include "mongo/platform/basic.h"
#include <string>
#include "mongo/db/pipeline/accumulation_statement.h"
#include "mongo/db/pipeline/accumulator.h"
#include "mongo/db/pipeline/value.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/mongoutils/str.h"
#include "mongo/util/string_map.h"
namespace mongo {
using boost::intrusive_ptr;
using std::string;
namespace {
// Used to keep track of which Accumulators are registered under which name.
static StringMap<Accumulator::Factory> factoryMap;
} // namespace
void AccumulationStatement::registerAccumulator(std::string name, Accumulator::Factory factory) {
auto it = factoryMap.find(name);
massert(28722,
str::stream() << "Duplicate accumulator (" << name << ") registered.",
it == factoryMap.end());
factoryMap[name] = factory;
}
Accumulator::Factory AccumulationStatement::getFactory(StringData name) {
auto it = factoryMap.find(name);
uassert(
15952, str::stream() << "unknown group operator '" << name << "'", it != factoryMap.end());
return it->second;
}
boost::intrusive_ptr<Accumulator> AccumulationStatement::makeAccumulator(
const boost::intrusive_ptr<ExpressionContext>& expCtx) const {
return _factory(expCtx);
}
AccumulationStatement AccumulationStatement::parseAccumulationStatement(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
const BSONElement& elem,
const VariablesParseState& vps) {
auto fieldName = elem.fieldNameStringData();
uassert(40234,
str::stream() << "The field '" << fieldName << "' must be an accumulator object",
elem.type() == BSONType::Object &&
elem.embeddedObject().firstElementFieldName()[0] == '$');
uassert(40235,
str::stream() << "The field name '" << fieldName << "' cannot contain '.'",
fieldName.find('.') == string::npos);
uassert(40236,
str::stream() << "The field name '" << fieldName << "' cannot be an operator name",
fieldName[0] != '$');
uassert(40238,
str::stream() << "The field '" << fieldName << "' must specify one accumulator",
elem.Obj().nFields() == 1);
auto specElem = elem.Obj().firstElement();
auto accName = specElem.fieldNameStringData();
uassert(40237,
str::stream() << "The " << accName << " accumulator is a unary operator",
specElem.type() != BSONType::Array);
return {fieldName.toString(),
Expression::parseOperand(expCtx, specElem, vps),
AccumulationStatement::getFactory(accName)};
}
} // namespace mongo
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