std::unique_ptr<ParsedAggregationProjection> ParsedAggregationProjection::create(
const BSONObj& spec) {
// Check for any conflicting specifications, and determine the type of the projection.
auto projectionType = ProjectSpecTypeParser::parse(spec);
// We can't use make_unique() here, since the branches have different types.
std::unique_ptr<ParsedAggregationProjection> parsedProject(
projectionType == ProjectionType::kInclusion
? static_cast<ParsedAggregationProjection*>(new ParsedInclusionProjection())
: static_cast<ParsedAggregationProjection*>(new ParsedExclusionProjection()));
// Actually parse the specification.
parsedProject->parse(spec);
return parsedProject;
}
std::unique_ptr<ParsedAggregationProjection> ParsedAggregationProjection::create(
const boost::intrusive_ptr<ExpressionContext>& expCtx, const BSONObj& spec) {
// Check that the specification was valid. Status returned is unspecific because validate()
// is used by the $addFields stage as well as $project.
// If there was an error, uassert with a $project-specific message.
ProjectionSpecValidator::uassertValid(spec, "$project");
// Check for any conflicting specifications, and determine the type of the projection.
auto projectionType = ProjectTypeParser::parse(spec);
// kComputed is a projection type reserved for $addFields, and should never be detected by the
// ProjectTypeParser.
invariant(projectionType != TransformerType::kComputedProjection);
// We can't use make_unique() here, since the branches have different types.
std::unique_ptr<ParsedAggregationProjection> parsedProject(
projectionType == TransformerType::kInclusionProjection
? static_cast<ParsedAggregationProjection*>(new ParsedInclusionProjection(expCtx))
: static_cast<ParsedAggregationProjection*>(new ParsedExclusionProjection(expCtx)));
// Actually parse the specification.
parsedProject->parse(spec);
return parsedProject;
}