Brainf*ck to Python transpiler

bf2py.py

#!/usr/bin/env python3
import sys
import argparse

TRANS = {
    # op: (nest, python_code)
    '>': (0, 'index += 1'),
    '<': (0, 'index -= 1'),
    '+': (0, 'memory[index] = (memory[index] + 1) & 0xff'),
    '-': (0, 'memory[index] = (memory[index] - 1) & 0xff'),
    '.': (0, 'sys.stdout.write(chr(memory[index]))'),
    ',': (0, 'memory[index] = ord(sys.stdin.read(1))'),
    '[': (1, 'while memory[index]:'),
    ']': (-1, ''),
}


def transpile(bf, memory_kib=8):
    """brainf*ckコードbfをpythonに変換（メモリサイズはmemory_kibキビバイト）"""
    yield 'import sys'
    yield f'memory = [0] * {memory_kib} * 1024'
    yield 'index = 0'
    indent = 0
    for op in bf:
        nest, py = TRANS.get(op, (0, ''))
        if py:
            yield '    ' * indent + py
        indent += nest


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('filename', help='input file name of brainf*ck source code')
    parser.add_argument('-e', '--execute', help='execute code', action='store_true')
    parser.add_argument('-m', '--memory', type=int, default=8, help='memory size in KiB')
    args = parser.parse_args()
    with open(args.filename) as f:
        (exec if args.execute else print)('\n'.join(transpile(f.read(), args.memory)))


if __name__ == '__main__':
    main()