Write Your Own Brainfuck Compiler

brainfuck.py

import sys
import ply.yacc as yacc
import ply.lex as lex

tokens = (
    'INCREMENT',
    'DECREMENT',
    'SHIFT_LEFT',
    'SHIFT_RIGHT',
    'OUTPUT',
    'INPUT',
    'OPEN_LOOP',
    'CLOSE_LOOP',
)

t_INCREMENT   = r'\+'
t_DECREMENT   = r'-'
t_SHIFT_LEFT  = r'<'
t_SHIFT_RIGHT = r'>'
t_OUTPUT      = r'\.'
t_INPUT       = r','
t_OPEN_LOOP   = r'\['
t_CLOSE_LOOP  = r'\]'

def t_newline(t):
    r'\n+'
    t.lexer.lineno += len(t.value)

t_ignore = ' \t'

def t_error(t):
    print("Illegal character '%s'" % t.value[0])
    t.lexer.skip(1)

def p_commands(p):
    """
    commands : command
             | commands command
    """
    if len(p) == 2:
        p[0] = Commands()
        p[0].commands = [p[1]]
        return

    if not p[1]:
        p[1] = Commands()

    p[1].commands.append(p[2])
    p[0] = p[1]

def p_command(p):
    """
    command : INCREMENT
            | DECREMENT
            | SHIFT_LEFT
            | SHIFT_RIGHT
            | OUTPUT
            | INPUT
            | loop
    """
    if isinstance(p[1], str): 
        p[0] = Command(p[1])
    else:
        p[0] = p[1]

def p_loop(p):
    """
    loop : OPEN_LOOP commands CLOSE_LOOP
    """
    p[0] = Loop(p[2])

def p_error(p):
    print("Syntax error in input!")


class BrainfuckProgram:
    def __init__(self, source):
        self.source = source

    def run(self):
        self.data = [0] * 20
        self.location = 0
        commands = self.parse(self.source)
        commands.run(self)

    def parse(self, source):
        lexer = lex.lex()
        parser = yacc.yacc()
        return parser.parse(source)

    def __str__(self):
        return str(self.parse(self.source))

class Commands:
    def __init__(self):
        self.commands = []

    def run(self, program):
        for command in self.commands:
            command.run(program)

    def __str__(self):
        return ''.join([str(command) for command in self.commands])

class Command:
    def __init__(self, command):
        self.command = command

    def run(self, program):
        if isinstance(self.command, Loop):
            self.command.run(program)

        if self.command == '+':
            program.data[program.location] += 1
        if self.command == '-':
            program.data[program.location] -= 1
        if self.command == '<':
            program.location -= 1
        if self.command == '>':
            program.location += 1
        if self.command == '.':
            sys.stdout.write(chr(program.data[program.location]))

    def __str__(self):
        return self.command

class Loop:
    def __init__(self, commands):
        self.commands = commands

    def run(self, program):
        while program.data[program.location] != 0:
            self.commands.run(program)

    def __str__(self):
        return '[' + str(self.commands) + ']'


source = '++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.'
program = BrainfuckProgram(source)
program.run()