Add brainfuck interpreter

[vinc]

I'm working on MOROS Shell 2.0 and I'll need a parser to handle the new language features. I don't like how hard it is with the nom crate to display good error messages with context for MOROS Lisp (which complicate a lot writing big programs inside MOROS), so I've been looking into the chumsky crate instead. That's the only issue I have with nom because it's a really good library otherwise.

When I learned how to use nom 4 years ago I added a small calc tool with a simple grammar (#263), so I'm now using the Brainfuck interpreter from the examples of the chumsky crate with the goal to extend it a bit and see if I like the crate.

I'm not sur if I'll merge this because I'm more interested in writing my own Brainfuck interpreter in MOROS Lisp, but I'm very interested in having a Brainfuck interpreter! Maybe I'll have both to compare the performance, like I did with the undocumented pi command (that I just remembered now).

[vinc]

Hello world example:

~
> read hello.bf
++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.++
+.------.--------.>>+.>++.

~
> brainfuck hello.bf
Hello World!

Default error message:

~
> brainfuck error.bf
Error: found 'X' expected '<', '>', '+', '-', ',', '.', '[', or end of input

[vinc]

Improved error message:

~
> brainfuck error.bf
Error: Unexpected token at error.bf:1:6

+++++X+++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++>
     ^ found 'X' expected '<', '>', '+', '-', ',', '.', '[', or end of input

[vinc]

The hello world example has been taken from Wikipedia and the 400 bytes quine from Daniel B Cristofani.

TODO: Add comment support for example attribution

[vinc]

~
> read hello.bf
+++++
               +++[>++
     ++[>+
+>+
++>+
++>
+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.++
+.---X--.--------.>>+.>++.

~
> brainfuck hello.bf
Error: Unexpected token at hello.bf:8:6

+.---X--.--------.>>+.>++.
     ^ unexpected token

[vinc]

Screenshot:

[viktorpopp]

Why is the X an unexpected token? Shouldn't all text just be ignored?

[vinc]

Why is the X an unexpected token? Shouldn't all text just be ignored?

All tokens that are not instructions are now ignored but that was not the case with the example parser I started with from the crate's repo.