java - 为 Antlr Java 8 语法添加注释

Question

当使用 antlr 的 Java8 语法时，我希望将“评论”记录到 AST 中(不是对它们做任何事情，而是为了以后的再现而存储)。 https://github.com/antlr/grammars-v4/blob/master/java8/Java8.g4

IE:我想将 java 源代码文件读入 AST，然后最终再次输出它，但要包含

我想知道是否对语法进行了简单的调整以允许这样做......(或者我必须将“评论”整合到每个表达式中的天真想法是否是事情的可悲事实...... ) 如果是的话……那是什么？

COMMENT
    :   '/*' .*? '*/' -> skip
    ;

LINE_COMMENT
    :   '//' ~[\r\n]* -> skip
    ;

Answer 1

据我所知，您可以通过以下方式将评论保留在他们自己的“ channel ”中:

将此添加到语法中:

@lexer::members {
    public static final int WHITESPACE = 1;
    public static final int COMMENTS = 2;
}

并更改为:

COMMENT
    : '/*' .*? '*/' -> channel(COMMENTS)
    ;

LINE_COMMENT
    : '//' ~[\r\n]* -> channel(COMMENTS)
    ;

来自:https://stackoverflow.com/a/17960734/2801237

官方“文档”(实际上看起来他的书真的是“真正的”文档)简要提到了这一点:

https://github.com/antlr/antlr4/blob/master/doc/grammars.md

这本书的(一个版本)说

you can send different tokens to the parser on different channels.For example, you might want whitespace and regular comments on onechannel and Javadoc comments on another when parsing Java

---

这是我收到的来自 antlr 一代的警告:(我读到你可以忽略这些，但是......可能有更好的方法来做到这一点)

warning(155): java8comments.g4:1725:35: rule WS contains a lexer command with an unrecognized constant value; lexer interpreters may produce incorrect output

warning(155): java8comments.g4:1729:33: rule DOC_COMMENT contains a lexer command with an unrecognized constant value; lexer interpreters may produce incorrect output

warning(155): java8comments.g4:1733:31: rule COMMENT contains a lexer command with an unrecognized constant value; lexer interpreters may produce incorrect output

warning(155): java8comments.g4:1737:31: rule LINE_COMMENT contains a lexer command with an unrecognized constant value; lexer interpreters may produce incorrect output