brainfuck.py

A Python brainfuck interpreter

Usage

python brainfuck.py input

Where input is a valid brainfuck file.

brainfuck.py can also be added to an existing project as a library

import brainfuck as bf

x = bf.Interpreter()
x.execute(brainfuck_program)

Installation

pip install -r requirements.txt

Currently brainfuck.py relies on getch to handle character input.

About brainfuck

From Wikipedia:

Brainfuck is an esoteric programming language noted for its extreme minimalism. The language consists of only eight simple commands and an instruction pointer. It is designed to challenge and amuse programmers, and was not made to be suitable for practical use. It was created in 1993 by Urban Müller.

Hello World

[ This program prints "Hello World!" and a newline to the screen, its
  length is 106 active command characters [it is not the shortest.]
 
  This loop is a "comment loop", it's a simple way of adding a comment
  to a BF program such that you don't have to worry about any command
  characters. Any ".", ",", "+", "-", "<" and ">" characters are simply
  ignored, the "[" and "]" characters just have to be balanced.
]
+++++ +++               Set Cell #0 to 8
[
    >++++               Add 4 to Cell #1; this will always set Cell #1 to 4
    [                   as the cell will be cleared by the loop
        >++             Add 2 to Cell #2
        >+++            Add 3 to Cell #3
        >+++            Add 3 to Cell #4
        >+              Add 1 to Cell #5
        <<<<-           Decrement the loop counter in Cell #1
    ]                   Loop till Cell #1 is zero; number of iterations is 4
    >+                  Add 1 to Cell #2
    >+                  Add 1 to Cell #3
    >-                  Subtract 1 from Cell #4
    >>+                 Add 1 to Cell #6
    [<]                 Move back to the first zero cell you find; this will
                        be Cell #1 which was cleared by the previous loop
    <-                  Decrement the loop Counter in Cell #0
]                       Loop till Cell #0 is zero; number of iterations is 8
 
The result of this is:
Cell No :   0   1   2   3   4   5   6
Contents:   0   0  72 104  88  32   8
Pointer :   ^
 
>>.                     Cell #2 has value 72 which is 'H'
>---.                   Subtract 3 from Cell #3 to get 101 which is 'e'
+++++++..+++.           Likewise for 'llo' from Cell #3
>>.                     Cell #5 is 32 for the space
<-.                     Subtract 1 from Cell #4 for 87 to give a 'W'
<.                      Cell #3 was set to 'o' from the end of 'Hello'
+++.------.--------.    Cell #3 for 'rl' and 'd'
>>+.                    Add 1 to Cell #5 gives us an exclamation point
>++.                    And finally a newline from Cell #6

Since brainfuck ignores all characters not in its language, the above is valid code that can be executed.

The above code can be simplified to

++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.

Wyvryn / brainfuck.py