Python 2.7及更高版本ANTLR4:使ANTLR在无效输入上引发异常 [英] Python 2.7 & ANTLR4 : Make ANTLR throw exceptions on invalid input

问题描述

我想捕捉类似的错误

line 1:1 extraneous input '\r\n' expecting {':', '/',}

line 1:1 mismatched input 'Vaasje' expecting 'Tafel'

我尝试将函数包装在try-catch中，但是，正如预期的那样，这些错误只是print语句，而不是异常.我在.g4文件中看到了一些打开错误的示例，但是所有示例都是针对Java的，我似乎无法使其正常工作.

I tried wrapping my functions in try-catch but, as expected, these errors are just print statement and not exceptions. I've seen some examples of switching on errors in the .g4 file, but all the examples are for Java, and I can't seem to get it working.

Python中的ANTLR4是否可能引发我可以捕获的异常?

Is it possible for ANTLR4 in Python to throw exceptions which I can catch?

推荐答案

我浏览了python类，发现它们没有java类提供的用于添加和删除错误侦听器的方法，这可能是bug ANTLR，但是python是python，您可以修改成员而无需诸如以下示例中所示的setter:

I have looked through the python classes and noticed that they dont have the methods that the java one has for adding and removing a error listener, this maybe a bug in ANTLR, however python being python you are allowed to modify the members without requiring a setter as such like in the following example:

我通过执行以下命令来运行示例:antlr4 -Dlanguage = Python2 AlmostEmpty.g4，然后输入main.py

I run the example by performing a : antlr4 -Dlanguage=Python2 AlmostEmpty.g4 and then by typing in main.py

AllowEmpty.g4

AlmostEmpty.g4

grammar AlmostEmpty;

animals: (CAT | DOG | SHEEP ) EOF;

WS: [ \n\r]+ -> skip;
CAT: [cC] [aA] [tT];
DOG: [dD] [oO] [gG];
SHEEP: [sS] [hH] [eE] [pP];

---

main.py

---

main.py

from antlr4 import *
import sys
from AlmostEmptyLexer import AlmostEmptyLexer
from AlmostEmptyParser import AlmostEmptyParser
from antlr4.error.ErrorListener import ErrorListener

class MyErrorListener( ErrorListener ):

    def __init__(self):
        super(MyErrorListener, self).__init__()

    def syntaxError(self, recognizer, offendingSymbol, line, column, msg, e):
        raise Exception("Oh no!!")

    def reportAmbiguity(self, recognizer, dfa, startIndex, stopIndex, exact, ambigAlts, configs):
        raise Exception("Oh no!!")

    def reportAttemptingFullContext(self, recognizer, dfa, startIndex, stopIndex, conflictingAlts, configs):
        raise Exception("Oh no!!")

    def reportContextSensitivity(self, recognizer, dfa, startIndex, stopIndex, prediction, configs):
        raise Exception("Oh no!!")

if __name__ == "__main__":
    inputStream = StdinStream( )
    lexer = AlmostEmptyLexer(inputStream)
    # Add your error listener to the lexer if required
    #lexer.removeErrorListeners()
    #lexer._listeners = [ MyErrorListener() ]
    stream = CommonTokenStream(lexer)
    parser = AlmostEmptyParser(stream)
    # As mentioned in the comments by @Tim Stewart instead of doing this:
    # parser._listeners = [ MyErrorListener() ]
    # you can do this:
    parser.addErrorListener( MyErrorListener() )
    tree = parser.animals()

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