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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.
*/
#include "mongo/db/pipeline/expression_function.h"
namespace mongo {
REGISTER_STABLE_EXPRESSION(function, ExpressionFunction::parse);
ExpressionFunction::ExpressionFunction(ExpressionContext* const expCtx,
boost::intrusive_ptr<Expression> passedArgs,
bool assignFirstArgToThis,
std::string funcSource,
std::string lang)
: Expression(expCtx, {std::move(passedArgs)}),
_passedArgs(_children[0]),
_assignFirstArgToThis(assignFirstArgToThis),
_funcSource(std::move(funcSource)),
_lang(std::move(lang)) {
expCtx->sbeCompatibility = SbeCompatibility::notCompatible;
}
Value ExpressionFunction::serialize(SerializationOptions options) const {
MutableDocument innerOpts(Document{{"body"_sd, options.serializeLiteral(_funcSource)},
{"args"_sd, _passedArgs->serialize(options)},
// "lang" is purposefully not treated as a literal since it
// is more of a selection of an enum
{"lang"_sd, _lang}});
// This field will only be seralized when desugaring $where in $expr + $_internalJs
if (_assignFirstArgToThis) {
innerOpts["_internalSetObjToThis"] = options.serializeLiteral(_assignFirstArgToThis);
}
return Value(Document{{kExpressionName, innerOpts.freezeToValue()}});
}
boost::intrusive_ptr<Expression> ExpressionFunction::parse(ExpressionContext* const expCtx,
BSONElement expr,
const VariablesParseState& vps) {
uassert(4660800,
str::stream() << kExpressionName << " cannot be used inside a validator.",
!expCtx->isParsingCollectionValidator);
uassert(31260,
str::stream() << kExpressionName
<< " requires an object as an argument, found: " << expr.type(),
expr.type() == BSONType::Object);
BSONElement bodyField = expr["body"];
uassert(31261, "The body function must be specified.", bodyField);
boost::intrusive_ptr<Expression> bodyExpr = Expression::parseOperand(expCtx, bodyField, vps);
auto bodyConst = dynamic_cast<ExpressionConstant*>(bodyExpr.get());
uassert(31432, "The body function must be a constant expression", bodyConst);
auto bodyValue = bodyConst->getValue();
uassert(31262,
"The body function must evaluate to type string or code",
bodyValue.getType() == BSONType::String || bodyValue.getType() == BSONType::Code);
BSONElement argsField = expr["args"];
uassert(31263, "The args field must be specified.", argsField);
boost::intrusive_ptr<Expression> argsExpr = parseOperand(expCtx, argsField, vps);
// This element will be present when desugaring $where, only.
BSONElement assignFirstArgToThis = expr["_internalSetObjToThis"];
BSONElement langField = expr["lang"];
uassert(31418, "The lang field must be specified.", langField);
uassert(31419,
"Currently the only supported language specifier is 'js'.",
langField.type() == BSONType::String && langField.str() == kJavaScript);
return new ExpressionFunction(expCtx,
argsExpr,
assignFirstArgToThis.trueValue(),
bodyValue.coerceToString(),
langField.str());
}
Value ExpressionFunction::evaluate(const Document& root, Variables* variables) const {
auto jsExec = getExpressionContext()->getJsExecWithScope(_assignFirstArgToThis);
auto scope = jsExec->getScope();
// createFunction is memoized in MozJSImplScope, so it's ok to call this for each
// eval call.
ScriptingFunction func = jsExec->getScope()->createFunction(_funcSource.c_str());
uassert(31265, "The body function did not evaluate", func);
auto argValue = _passedArgs->evaluate(root, variables);
uassert(31266, "The args field must be of type array", argValue.getType() == BSONType::Array);
// This logic exists to desugar $where into $expr + $function. In this case set the global obj
// to this, to handle cases where the $where function references the current document through
// obj.
BSONObjBuilder bob;
if (_assignFirstArgToThis) {
// For defense-in-depth, The $where case will pass a field path expr carrying $$CURRENT as
// the only element of the array.
auto args = argValue.getArray();
uassert(31422,
"field path $$CURRENT must be the only element in args",
argValue.getArrayLength() == 1);
BSONObj thisBSON = args[0].getDocument().toBson();
scope->setObject("obj", thisBSON);
return jsExec->callFunction(func, bob.done(), thisBSON);
}
int argNum = 0;
for (const auto& arg : argValue.getArray()) {
arg.addToBsonObj(&bob, "arg" + std::to_string(argNum++));
}
return jsExec->callFunction(func, bob.done(), {});
};
} // namespace mongo
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