Brim is an optimizing brain* interpreter than nonetheless strives to be very pleasant and easy to use.
Brim uses a wrapping 30000-cell tape, with a single wrapping unsigned byte in each cell.
If compiled in debug mode, or with the feature flag debug, brim will
recognize the character ;. This will dump several relevant bits of info
(the tape, the tape pointer, and three instructions for context) to
output.
With the -i | --input and -o | --output flags, brim can read/write to/from
files instead of stdin/stdout.
Regardless of source or destination, all I/O is buffered to provide a fast and reliable experience (the output is flushed on each newline, and upon exit).
Brim internally uses a token-based intermediary structure to execute the code. First, it groups together add, subtract, left, and right instructions to eliminate repetitive cycles (as well as discard redundant instructions).
Then, it performs several macro-optimizations to reduce common operations to a single "instruction". Currently, it recognizes:
[-])[-]++++)[->+<] / [>+<-])The token-based structure makes these trivial to recognize, since repeating instructions have already been collapsed into one.
Finally, it iterates over each bracket ([/]) and pre-loads its destination,
so executing them requires zero lookup time (it just overrides the IP).
These are all run in a buffered I/O environment, as detailed above.
This crate is also available as a library. The executable simply provides a CLI
interface to the library. The points of interest are the parse and optimize
functions, as well as the Token enum.
Brim isn't finished yet! My hopes for the future include:
Contributions are always welcome, especially optimizations. Please, before you
create a pull request, run cargo fmt and cargo clippy.
If you want to implement a new feature, consider gating it behind a feature flag. This can reduce code size as well as slightly improve runtimes. It isn't appropriate for all additions, but it is worth considering.