3 ms·

C++ has had run-time regular expressions in its standard library since C++11, but this is about compile-time regular expressions

• burntsushi 3y ago
  I've never used cl-ppcre myself, but its docs[1] claim that it provides compile-time regexes: > CL-PPCRE uses compiler macros to pre-compile scanners at load time if possible. This happens if the compiler can determine that the regular expression (no matter if it's a string or an S-expression) is constant at compile time and is intended to save the time for creating scanners at execution time (probably creating the same scanner over and over in a loop). [1]: https://edicl.github.io/cl-ppcre/ https://edicl.github.io/cl-ppcre/
  • foota 3y ago
    I think this is more like caching the regex than creating it at compile time? Load time I think is basically runtime. I think lisp can be loaded and then rehydrated later, but I'm not sure how common that is.
    • burntsushi 3y ago
      Hard to say exactly since I don't have experience with cl-ppcre, but this line seems to suggest something is actually happening at complile time: > This happens if the compiler can determine that the regular expression (no matter if it's a string or an S-expression) is constant at compile time If this were just a run of the mill caching mechanism, then whether the pattern was a constant at compile time wouldn't matter.