Python 2.7 使用PLY匹配正常字符串

我正在使用编写解析器。这个问题和这个类似。但是，我使用双引号打开和关闭字符串。例如：

“我不知道A是什么”

我将普通字符串lexer定义为：

t_NORMSTRING = r'"([^"\n]|(\\"))*"$'

我还有一个变量的lexer：

def t_VAR(t):
   r'[a-zA-Z_][a-zA-Z_0-9]*'

问题是我的lexer无法将“我不知道”A“是什么”识别为NORMSTRING标记。它返回错误

Illegal character '"' at 1
Syntax error at 'LexToken(VAR,'do',10,210)'

---

请告诉我为什么不正确。

通过一个小PLY程序探讨了这个问题，我认为您的问题与数据处理方面的差异有关，而不是PLY解析和词汇匹配本身。（作为旁注，两者在字符串处理方面有一些细微的区别。我将我的代码限制为python v2）

只有在使用非原始字符串或使用

input

而不是

raw\u input

时，您才会看到错误。下面是我的示例代码和结果：

命令：

$ python --version
Python 2.7.5
$ python string.py

输出：

Data: '"I do not know what \"A\" is"'
String: '"I do not know what \"A\" is"'

Data: '"I do not know what "A" is"'
Illegal character '"'
Illegal character '"'
String: '" is"'

Please type your line: "I do not know what \"A\" is"
String: '"I do not know what \"A\" is"'

Please type your line: "I do not know what \"A\" is"
Illegal character '"'
Illegal character '"'

输出：

Data: '"I do not know what \"A\" is"'
String: '"I do not know what \"A\" is"'

Data: '"I do not know what "A" is"'
Illegal character '"'
Illegal character '"'
String: '" is"'

Please type your line: "I do not know what \"A\" is"
String: '"I do not know what \"A\" is"'

Please type your line: "I do not know what \"A\" is"
Illegal character '"'
Illegal character '"'

输出：

Data: '"I do not know what \"A\" is"'
String: '"I do not know what \"A\" is"'

Data: '"I do not know what "A" is"'
Illegal character '"'
Illegal character '"'
String: '" is"'

Please type your line: "I do not know what \"A\" is"
String: '"I do not know what \"A\" is"'

Please type your line: "I do not know what \"A\" is"
Illegal character '"'
Illegal character '"'

输出：

Data: '"I do not know what \"A\" is"'
String: '"I do not know what \"A\" is"'

Data: '"I do not know what "A" is"'
Illegal character '"'
Illegal character '"'
String: '" is"'

Please type your line: "I do not know what \"A\" is"
String: '"I do not know what \"A\" is"'

Please type your line: "I do not know what \"A\" is"
Illegal character '"'
Illegal character '"'

最后，在正则表达式中可能不需要字符串锚点

$