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#!/usr/bin/env python3
 
from math import sqrt
 
class primes(object):
    def __init__(self, n):
        # 構造体と違うのは、与えられたデータが一つでも、「計算に使うデータ」を
        # 内部的に設定しておける、と言う辺りだ。
        self.n = n
        self.lst = list(range(2, n + 1))
    def __iter__(self):
        return self
    def __next__(self):
        if self.lst == []:
            raise StopIteration
        else:
            match self.lst:
                case [head, *tail]:
                    self.lst = tail if head > sqrt(self.n) \
                               else [i for i in self.lst if i % head != 0]
                    return head
 
class prime_factors(object):
    def __init__(self, n):
        self.n = n
        self.N = n
        self.primes = list(primes(n))
    def __iter__(self):
        return self
    def __next__(self):
        while True:
            match self.primes:
                case [head, *tail]:
                    if head > sqrt(self.N):
                        raise StopIteration
                    elif self.n % head == 0:
                        self.n //= head
                        return head
                    else:
                        self.primes = tail
 
if __name__ == '__main__':
    print(list(primes(120)))          # 120以下の素数
    print(list(prime_factors(48)))    # 48 を素因数分解
    print(list(prime_factors(20100))) # 20100 を素因数分解
 

Traceback (most recent call last):
  File "/usr/lib/python3.9/py_compile.py", line 144, in compile
    code = loader.source_to_code(source_bytes, dfile or file,
  File "<frozen importlib._bootstrap_external>", line 918, in source_to_code
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "./prog.py", line 17
    match self.lst:
          ^
SyntaxError: invalid syntax

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3.9/py_compile.py", line 150, in compile
    raise py_exc
py_compile.PyCompileError:   File "./prog.py", line 17
    match self.lst:
          ^
SyntaxError: invalid syntax

Standard output is empty