Function queryToPredicate

src/ExtMsg.actor.cpp:126–159

* Converts a mongo-like query document (query in the above grammar) into a corresponding * QL predicate. */

 *  QL predicate.
 */
Reference<IPredicate> queryToPredicate(bson::BSONObj const& query, bool toplevel) {
	std::vector<Reference<IPredicate>> terms;

	for (auto i = query.begin(); i.more();) {
		auto el = i.next();

		if (el.type() == bson::BSONType::RegEx) {
			terms.push_back(re_predicate(el, el.fieldName()));
		} else if (el.fieldName()[0] == '$') {
			if (el.isABSONObj()) {
				try {
					terms.push_back(ExtBoolOperator::toPredicate(el.fieldName(), el.Obj()));
				} catch (Error& e) {
					if (e.code() == error_code_bad_dispatch)
						throw fieldname_with_dollar();
					else
						throw;
				}
			} else {
				throw fieldname_with_dollar();
			}
		} else if (el.isABSONObj() && !is_literal_match(el.Obj())) {
			// If this is a top-level _id path then force use of elemMatch because _id can NOT be an array.
			if (toplevel && strcmp(el.fieldName(), DocLayerConstants::ID_FIELD) == 0)
				terms.push_back(ExtValueOperator::toPredicate("$elemMatch", el.fieldName(), el));
			else
				valueQueryToPredicates(el.Obj(), el.fieldName(), terms);
		} else {
			terms.push_back(eq_predicate(el, el.fieldName()));
		}
	}

	return Reference<IPredicate>(new AndPredicate(terms));
}

Reference<Plan> planQuery(Reference<UnboundCollectionContext> cx, bson::BSONObj const& query) {
	auto predicate = queryToPredicate(query, true);