我在 Python 中使用 PLY 创建词法分析器时遇到问题

问：

我最近试图创建一个 Lexer，但效果不佳。

问题是它抛出一条错误消息，显示“无法构建词法分析器”。以下是回溯：

ERROR: Rule 't_TIMES' defined for an unspecified token TIMES
ERROR: Rule 't_DIVIDE' defined for an unspecified token DIVIDE
Traceback (most recent call last):
  File "...\Lexer.py", line 24, in <module>
    lexer = lex.lex()
            ^^^^^^^^^
  File "...\lex.py", line 910, in lex
    raise SyntaxError("Can't build lexer")
SyntaxError: Can't build lexer

我知道这是因为我的功能。我也感觉到我制作的令牌可能有问题。请帮帮我，我知道这有点愚蠢，但我是新来的，所以请对我好一点。 顺便说一句，这是源代码t_error()

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

import sys

tokens = [
    "INT",
    "ID",
    "PLUS",
    "MINUS",
    "EOF",
]

t_INT = r"\d+"
t_ID = r"[a-zA-Z_][a-zA-Z0-9_]*"
t_PLUS = r"+"
t_MINUS = r"-"
t_TIMES = r"*"
t_DIVIDE = r"/"

def t_error(t):
    print("Illegal character '%s'" % t.lexer.lexeme, file=sys.stderr)

lexer = lex.lex()

def p_expression(p):
    """expression : INT
                 | ID
                 | expression PLUS expression
                 | expression MINUS expression
                 | expression TIMES expression
                 | expression DIVIDE expression"""
    if len(p) == 2:
        if isinstance(p[1], int):
            p[0] = p[1]
        elif isinstance(p[1], str):
            p[0] = p[1]
    else:
        if p[2] == "+":
            p[0] = p[1] + p[3]
        elif p[2] == "-":
            p[0] = p[1] - p[3]
        elif p[2] == "*":
            p[0] = p[1] * p[3]
        elif p[2] == "/":
            p[0] = p[1] / p[3]

parser = yacc.yacc()

def test(text):
    try:
        result = parser.parse(text)
        if result:
            print(result)
        else:
            print("Empty expression")
    except yacc.YaccError:
        print("Error parsing input")

if __name__ == "__main__":
    test("123")
    test("hello")
    test("123 + 456")
    test("123 - 456")
    test("123 * 456")
    test("123 / 456")

也许我只是愚蠢，但正因为如此，所以我无法让它跑。