Rust-brainfuck

A Brainfuck interpreter made in Rust.

• Yes, it works, and it's fully compliant.
• No, it is not very fast (or at all (yet)).
• Yes, it is overkill.
• Yes, it is useless. Man, did you play with receipts as a kid or something?

Usage

Make sure to have Rust 0.10 and Make available:

$ make
mkdir -p dist
rustc -O --out-dir dist src/lib.rs
rustc -O -L dist -o dist/bf src/main.rs

$ echo "Lbh unir n ehfgl yrnx, znqnz." | dist/bf examples/rot13.bf
You have a rusty pipe, madam.

Notes

• EOF is represented as zero. Be sure to take that into account when running your programs. For example, the rot13 program described on Wikipedia won't work here.

• I/O operators , and . read from STDIN and write to STDOUT respectively.

Motivation

I am learning Rust, and Brainfuck happens to be a fun, simple project, which satisfies the following requisites:

• Small: it is compact enough to be kept entirely in the head at once.
• Flexible: it can be tackled in many different ways.
• Comprehensive: it requires learning many different things.

Plans and considerations

• Test coverage is practically non-existent.

• There is some unnecessary cloning of data, and many instantiation and borrows are probably more costly or less strict than they should. I was kinda expecting this to happen, though.

• Parsing is not very efficient at the moment. Besides, non-orthogonal operators like Incr and Decr, or Prev and Next could be compacted to Mutate and Seek. It makes sense to lose the 1:1 compliance to the source to enable some low-hanging optimizations like operator condensation.

• There are many interesting variations on the base language, which could be put behind some flag.

• It should be easy enough to add a debugger (a rewindable one would be nice).

• Performance is laughable, especially when compared to stuff like bff4. Rust's integrated micro-benchmarking may help with that. Right now I believe the culprits could be the many unneeded string manipulations, copying of data, and the unoptimized parsed tree.

• It shouldn't be too hard to produce a compiled binary, or some custom byte-code. By the way, I saw some nice LLVM helpers hidden inside Rustc.

• It should be embeddable. And read mail.