Hallo Users, this time a question about retaining the comments in the recursive AST. I've never seen those question before. I have a grammar that can have a comment at any point while maintaining that same grammar. I am interested in the comments to be able to parse the possibly contained pragma etc. statement later (so parsed as raw). ... auto const comment_def =        x3::lit("//")     >> raw[*(char_ - x3::eol) >> x3::eol]; ... The AST is ready, an AST node for the comment is also there. How do I change the rule now? auto const start_def =     x3::skip(x3::space)[           comment         | toplevel_rule     ]; with the actual parse function: ... x3::parse(iter, end, toplevel_parser >> x3::eoi, toplevel);  .... originally the latter looked like this: .... x3::phrase_parse(iter, end, toplevel_parser >> x3::eoi, parser::skipper, toplevel); ... The above start_def unfortunately also changes the attribute for it, ast::toplevel_node now becomes a variantast::comment_node,ast::toplevel_node. I'm also not sure how this rule affects the dependent rules, i.e. recursive and low level in terms of correctness and performance. For the AST visitor this just means another overload. Another point is the test suite. Currently I test the low level sub rules with a separate instance, where the test input can also contain comments for test case documentation purpose. With x3::phrase_parse() this was not a problem. With the new approach, for each rule to be tested, I also have to use a variant for the attribute, which is very inconvenient.... So the question, is this really the right way? Are there alternatives? Thanks in advance