如何获取antlr4规则匹配的原始文本？ [英] How do I get the original text that an antlr4 rule matched?

问题描述

使用Java 7语法 https://github.com /antlr/grammars-v4/blob/master/java7/Java7.g4 我想找到具有特定名称的方法，然后打印出该方法。我看到匹配时我可以使用 methodDeclaration 规则。所以我子类 Java7BaseListener 并覆盖这个监听器方法：

Using the Java 7 grammar https://github.com/antlr/grammars-v4/blob/master/java7/Java7.g4 I want to find methods with a specific name and then just print out that method. I see that I can use the methodDeclaration rule when I match. So I subclass Java7BaseListener and override this listener method:

@Override public void enterMethodDeclaration(Java7Parser.MethodDeclarationContext ctx) { }

如何获取原始文本？ ctx.getText（）给我一个字符串，其中删除了所有空格。我想要评论和原始格式。

How do I get the original text out? ctx.getText() gives me a string with all the whitespace stripped out. I want the comments and original formatting.

推荐答案

ANTLR的 CharStream 类有方法 getText（间隔间隔），它将返回给定范围内的原始源。 Context 对象具有获取开头和结尾的方法。假设你的监听器中有一个名为 input 的字段，它正在解析CharStream，你可以这样做：

ANTLR's CharStream class has a method getText(Interval interval) which will return the original source in the give range. The Context object has methods to get the beginning and end. Assuming you have a field in your listener called input which has the CharStream being parsed, you can do this:

    int a = ctx.start.getStartIndex();
    int b = ctx.stop.getStopIndex();
    Interval interval = new Interval(a,b);
    input.getText(interval);

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