bfcxx: A brainfuck interpreter

Brainfuck is a Turing complete esoteric programming language created in 1993 by Urban Müller. The language operates using a pointer that moves along an array of memory cells, each of which can store a single byte, although some implementations use 4-byte cells.

It consists of only 8 commands:

Command	bfcxx interpretation
<	Move the pointer to the left
>	Move the pointer to the right
+	Increment the memory cell at the pointer
-	Decrement the memory cell at the pointer
.	Write the character at the pointer to standard output
,	Read a character from standard input and store it at the pointer
[	Jump forward to the command after the matching ] if the memory cell at the pointer is zero
]	Jump back to the command after the matching [ if the memory cell at the pointer is nonzero

Building

A C++20 compatible compiler and CMake 3.21 are required. To build the project, run:

cmake --build --preset <preset-name>

where <preset-name> is the name of the preset to use. To list all available presets, run:

cmake --list-presets

This will create an out directory with the compiled executable for the CLI at /out/build/<preset-name>/source/bfcxx/cli/bfcxx.

Usage

The interpreter can be used as a read-eval-print loop (primitive, only a single line at a time) or to interpret a file:

bfcxx [path-to-file]

/programs contains a few example programs to test the interpreter.

Optimizations

The interpreter uses couple optimizations to improve performance:

• Jump table: Jump table is used to quickly find the matching bracket for [ and ] commands.
• Run-length encoding: Consecutive +, -, <, and > commands are combined into a single command thus reducing the number of operations.