There are several ways đŸ™‚ Custom attribute traits The same using semantic actions Everything in semantic actions, at detail level 1. Custom attribute traits The cleanest, IMO would to replace the Fusion Sequence Adaptation (BOOST_FUSION_ADAPT_STRUCT) by custom container attribute traits for Spirit: namespace boost { namespace spirit { namespace traits { template<> struct is_container<ElemParseData, void> … Read more
I have given things a quick scan. My profiler quickly told me that constructing the grammar and (especially) the lexer object took quite some resources. Indeed, just changing a single line in SpiritParser.cpp saved 40% of execution time1 (~28s down to ~17s): lexer::Lexer lexer; into static const lexer::Lexer lexer; Now, making the grammar static involves … Read more
It seems I am so close, i.e. just a few changes to the double_ parser and I’d be done. This would probably be a lot more maintainable than adding a new grammar, since all the other parsing is done that way. – toting 7 hours ago Even more maintainable would be to not write another … Read more
For a background on parsing (optionally) quoted delimited fields, including different quoting characters (‘, “), see here: Parse quoted strings with boost::spirit For a very, very, very complete example complete with support for partially quoted values and a splitInto(input, output, ‘ ‘); method that takes ‘arbitrary’ output containers and delimiter expressions, see here: How to … Read more
It’s not the string matcher per se. It’s [attribute propagation] + [backtracking] in action. A string attribute is a container attribute and many elements could be assigned into it by different parser subexpressions. Now for efficiency reasons, Spirit doesn’t rollback the values of emitted attributes on backtracking. Often this is no problem at all, but … Read more
Your example I don’t see how your sample requires any of this. Just reorder your branches, then realize that the short branch is just a special case of the qualified case with n=1: Live On Coliru¹ (or using X3 version if you prefer). The generic case Now, having mentioned x3, it has the capacity to … Read more
Update X3 version added First off, you fallen into a deep trap here: Qi rules don’t work with auto. Use qi::copy or just used qi::rule<>. Your program has undefined behaviour and indeed it crashed for me (valgrind pointed out where the dangling references originated). So, first off: const auto rule = qi::copy(qi::int_ >> ‘:’ >> … Read more
It’s a bug in your code, nothing wrong with the compiler or the optimization levels. The cinch is with expression templates (like the ones used by Boost Proto, and hence by Boost Spirit). They are only valid to the end of their enclosing full expression [1] The canonical workaound is: BOOST_SPIRIT_AUTO(ana, *~qi::char_(‘*’) > +qi::char_(‘*’)); You … Read more
The reference to qq becomes dangling after leaving the constructor, so that is indeed a problem. qi::locals is the canonical way to keep local state inside parser expressions. Your other option would be to extend the lifetime of qq (by making it a member of the grammar class, e.g.). Lastly, you might be interested in … Read more
This is a quite infamous edge-case in Spirit. The problem is, special-case handling of single-element Fusion Sequences in Spirit breaks some abstractions. The usual workaround is to adapt the exposed-attribute side to be less-trivial: rule<It, single_member_struct()> r = eps >> XXX; // the `eps` is there to break the spell However, here that won’t work, … Read more