问题描述：如何使用Antlr4 for Python将数据解析为各个部分？

解决思路：使用Antlr4 for Python生成解析器，然后使用该解析器解析数据，最后将数据分解为各个部分。

示例代码：

1.定义解析器规则

grammar MyGrammar;

data: section+;

section: START_SECTION section_body END_SECTION;

section_body: (key_value_pair)+;

key_value_pair: key EQUALS value;

key: ID;

value: STRING | NUMBER;

START_SECTION: '[';

END_SECTION: ']';

EQUALS: '=';

ID: [a-zA-Z]+;

STRING: '"' (~[\r\n"])* '"' ;

NUMBER: '-'? INT ( '.' INT )?;

INT: [0-9]+;

2.使用Antlr4生成Python解析器

import antlr4
from MyGrammarLexer import MyGrammarLexer
from MyGrammarParser import MyGrammarParser

class MyListener(MyGrammarParser):
    pass

lexer = MyGrammarLexer(antlr4.InputStream(data))
stream = antlr4.CommonTokenStream(lexer)
parser = MyGrammarParser(stream)
listener = MyListener()
walker = antlr4.ParseTreeWalker()
walker.walk(listener, parser.data())

3.自定义解析器Listener

class MyListener(MyGrammarParser):

    def enterSection(self, ctx:MyGrammarParser.SectionContext):
        print("Found section: " + ctx.getStart().getText())

    def enterKey_value_pair(self, ctx:MyGrammarParser.Key_value_pairContext):
        key = ctx.key().getText()
        value = ctx.value().getText()
        print("Found key-value pair: " + key + "=" + value)

4.解析数据

data = '[section1]\nkey1=value1\nkey2=value2\n[section2]\nkey1=value1\nkey2=value2\n'
lexer = MyGrammarLexer(antlr4.InputStream(data))
stream = antlr4.CommonTokenStream(lexer)
parser = MyGrammarParser(stream)
listener = MyListener()
walker = antlr4.ParseTreeWalker()
walker.walk(listener, parser.data())

结果输出：

Found section: section1
Found key-value pair: key1