boost::spirit X3 -- Why can it not be found from the list of libraries?

Question

Why is this library not listed in the directory of the matching boost version? What are the differences compared to v2.*? What are the required/supported C++ standards?

Answer 1

X3 is not a boost library. It's a component of the Boost Spirit library.

The documentation is here: https://www.boost.org/doc/libs/1_82_0/libs/spirit/doc/x3/html/index.html

It requires c++14, but there are deprecation warning that in the future they will only support c++17. In fact I just found (on that page) they already do:

WARNING*: C++14 compilers support will be dropped soon. Spirit X3 in Boost 1.81 (scheduled to November 2022) will use C++17 features.

The differences are legion, but you can find them by reading the docs.

I guess besides that, you can find some of that info on this site:

1. Maturity

   - https://stackoverflow.com/questions/48237777/is-boost-spirit-x3-production-ready/48239766#48239766
   - https://stackoverflow.com/questions/45014216/how-future-safe-is-it-to-write-a-parser-with-boost-spirit-x3/45015809#45015809
   - https://stackoverflow.com/questions/52990661/getting-into-boost-spirit-qi-or-x3/52991170#52991170
   

2. Differences

   • Statefulness of Spirit V2 and X3
   • What are contexts in boost spirit X3?

3. Overcoming differences/missing bits:

   • Spirit X3: parser with internal state
   • Boost Spirit X3 cannot compile repeat directive with variable factor
   • Boost spirit x3 - lazy parser

4. Advanced Use

   • Spirit X3, Is this error handling approach useful?
   • Is it possible to use "boost::spirit::qi::as_string" in a loop? If so, can someone help me find the solution?

5. Common Pitfalls

   • Spirit X3, How to get attribute type to match rule type?
   • boost::spirit::x3 attribute compatibility rules, intuition or code?
   • Boost.Spirit X3 compile time explodes with recursive rule
   • Unresolved symbols due to varying contexts https://stackoverflow.com/search?q=user%3A85371+x3+unresolved

I could go on, but it's probably better to search/ask targeted questions if you run into more.

TL/DR

As I happen to have recommended someone else yesteday:

@sehe. Since I'm using the latest boost version (1.82,0), do you recommend using QI or X3 for this project? They both new for me to learn anyway. I just don't want to spend time upgrading this to X3 in the future. – Dylan 6 hours ago

I think Qi is more mature and has fewer surprises (especially surrounding automatic propagation). However, X3 is a lot quicker to compile. If you are prepared to do a lot manual massaging with semantic actions anyways, X3 might be easier, since they're bit more natural now. – sehe 5 hours ago