presto-parser/src/main/java/io/prestosql/sql/parser/AstBuilder.java/AstBuilder/visitDereference
class AstBuilder:    @Override
    public Node visitDereference(SqlBaseParser.DereferenceContext context)
    {
        return new DereferenceExpression(
                getLocation(context),
                (Expression) visit(context.base),
                (Identifier) visit(context.fieldName));
    }