This is almost standard C++, except for the use of clang++/g++ computed labels extension. At the time of writing (Aug 2020), it is the fastest non-JIT interpreter for the commonly referenced mandelbrot and hanoi BF programs.
For a clear explanation of the computed labels, see the slower but more lucid code in https://github.com/JohnCGriffin/BF-computed-goto.
Step 1 - The Makefile is set to use clang++. Change to g++ if you prefer.
Step 2 - On a Unix machine, use make.
Step 3 - make test to try it on the included mandelbrot.bf,
a common exercise in BF land.