split_string.py

def split_string(string):
    buf = []
    result = []
    buffer = ""
    for i in string:
        if i in "()[]{}\"'":
            continue
        if i in ".?!\n":
            result.append(buf + [buffer])
            buffer = ""
            buf = []
        elif i.isalpha():
            buffer += i
        elif i.isspace():
            buf.append(buffer)
            buffer = ""
        else:
            buf.append(buffer)
            buffer = ""
            buf.append(i)
    if buffer:
        result[-1].append(buffer)

    return [[j for j in i if j] for i in result]