simple-parser-v1.py

gistfile1.py

# only consider base case
from enum import Enum, auto

import re
from typing import List, Union


class Status(Enum):
    Normol = auto()
    Number = auto()


class Type(Enum):
    digit = auto()
    operator = auto()
    space = auto()
    unkonwn = auto()


s = """111 + 2 - 5 / 6 +    888"""


def str2type(s: str):
    if re.match("[0-9]", s):
        return Type.digit
    if re.match(r"[\+\-\*\/]", s):
        return Type.operator
    if s.isspace():
        return Type.space
    return Type.unkonwn


index = 0
arr: List[Union[str, int]] = []
status = Status.Normol
cur = ""
while index < len(s):
    fast = s[index]

    match (status, str2type(fast)):
        case (Status.Normol, Type.digit):
            cur += fast
            status = Status.Number
        case (Status.Normol, Type.operator):
            arr.append(fast)
        case (Status.Normol, Type.space):
            # ignore
            ...
        case (Status.Number, Type.digit):
            cur += fast
        case (Status.Number, Type.operator):
            arr.append(int(cur))
            cur = ""
            arr.append(fast)
            status = Status.Normol

        case (Status.Number, Type.space):
            arr.append(int(cur))
            cur = ""
            status = Status.Normol
        case (_, Type.unkonwn):
            ...
    index += 1
arr.append(int(cur))
print(arr)