使用 ANTLR 用 Python 解析一些 Java 代码

问题描述

我想在 Python 中使用 ANTLR 构建一个 Java 解析器.

I want to build a Java parser using ANTLR in Python.

我从 ANTLR 存储库下载了语法:

I downloaded the grammars from the ANTLR repository:

词法分析器:https://github.com/antlr/grammars-v4/blob/master/java/java/JavaLexer.g4

解析器:https://github.com/antlr/grammars-v4/blob/master/java/java/JavaParser.g4

然后我用我的 script.bat 来生成我需要的 python 代码:

Then I used my script.bat to generate the python code I need :

java -jar antlr-4.8-complete.jar -Dlanguage=Python3 Java8Lexer.g4
java -jar antlr-4.8-complete.jar -Dlanguage=Python3 Java8Parser.g4

antlr-4.8-complete.jar 在此处下载:https://www.antlr.org/download/antlr-4.8-complete.jar

这生成了这个文件列表:

This generated this list of files:

• Java8Lexer.interp
• Java8Lexer.py
• Java8Lexer.tokens
• Java8Parser.interp
• Java8Parser.py
• Java8Parser.tokens
• Java8ParserListener.py

然后我写了这段代码来解析一个java文件:

Then I wrote this code to parse a java file:

import antlr4
from antlr4 import *
from java.antlr_unit2 import Java8Parser, Java8Lexer

def main():
    code = open('test.txt', 'r').read()
    lexer = Java8Lexer.Java8Lexer(antlr4.InputStream(code))
    stream = antlr4.CommonTokenStream(lexer)
    parser = Java8Parser.Java8Parser(stream)
    tree = parser.expression()
    print (tree)

if __name__ == '__main__':
    main()

我的测试java代码test.txt是这样的:

My test java code test.txt is something like this:

package org.jabref.gui.fieldeditors;
import java.util.ArrayList;
/**
 * This class contains some code
 */
public class TextInputControlBehavior {

    private static final boolean SHOW_HANDLES = Properties.IS_TOUCH_SUPPORTED && !OS.OS_X;

}

由于太短，这里是我想解析的代码示例:https://pastebin.com/KNxfasKQ

Since this is too short, here is an example of code I want to parse: https://pastebin.com/KNxfasKQ

当我运行这段代码时，我得到了这个:

When I run this code I get this :

line 1:0 extraneous input 'package' expecting {'boolean', 'byte', 'char', 'double', 'float', 'int', 'long', 'new', 'short', 'super', 'this', 'void', IntegerLiteral, FloatingPointLiteral, BooleanLiteral, CharacterLiteral, StringLiteral, 'null', '(', '!', '~', '++', '--', '+', '-', Identifier, '@'}
[]

我做错了吗?语法不是我写的，我只是从ANTLR repo里拿来的.

Am I doing something wrong? I didn't wrote the grammar, I just took it from ANTLR repo.

编辑:Pavel Smirnov 的回答帮助了我，现在我没有收到警告.但是现在程序看起来很慢，我得到一个空树作为输出.

EDIT: Pavel Smirnov's answer helped me and now I don't get the warning. But now the program seems really slow and i get an empty tree as output.

解决:我正在打印tree，但我不得不print(tree.toStringTree(recog=parser))

SOLVED: I was printing tree but I had to print(tree.toStringTree(recog=parser))

所以最后的代码是:

import antlr4
from antlr4 import *
from java.antlr_unit2 import Java8Parser, Java8Lexer

def main():
    code = open('test.txt', 'r').read()
    lexer = Java8Lexer.Java8Lexer(antlr4.InputStream(code))
    stream = antlr4.CommonTokenStream(lexer)
    parser = Java8Parser.Java8Parser(stream)
    tree = parser.compilationUnit()
    print(tree.toStringTree(recog=parser))

if __name__ == '__main__':
    main()

推荐答案

您的文本文件包含一个 compilationUnit，而不是您尝试使用

Your text file contains a compilationUnit, not an expression you try to parse with

tree = parser.expression()

仔细看解析器规则，你需要的规则是

Look carefully through the parser rules, the rule you need is

compilationUnit
    : packageDeclaration? importDeclaration* typeDeclaration* EOF
    ;

必须被称为

tree = parser.compilationUnit()

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