在Antlr4中使用text属性时如何保留空白 [英] How to preserve whitespace when we use text attribute in Antlr4

问题描述

当我调用token的text属性时，我想保留空格，有什么办法吗? 情况如下: 我们有以下代码

I want to keep white space when I call text attribute of token, is there any way to do it? Here is the situation: We have the following code

IF L > 40 THEN;

ELSE

  IF A = 20 THEN
      PUT "HELLO";

在这种情况下，我想将其转换为:

In this case, I want to transform it into:

if (!(L>40){

      if (A=20)
          put "hello";
}

Antlr中的规则是:

The rule in Antlr is that:

stmt_if_block: IF expr
               THEN x=stmt
               (ELSE y=stmt)?
               {
                 if ($x.text.equalsIgnoreCase(";"))
                 {
                   WriteLn("if(!(" + $expr.text +")){");
                   WriteLn($stmt.text);
                   Writeln("}");
                 }
               }

但是结果看起来像:

if(!(L>40))
{
   ifA=20put"hello";
}

原因是$stmt中的空白已被删除.我想知道是否还有保留这些空白的空间
非常感谢

The reason is that the white space in $stmt was removed. I was wondering if there is anyway to keep these white space
Thank you so much

更新:如果我添加

SPACE: [ ] -> channel(HIDDEN);

将保留该空间，并且结果如下所示，令牌之间有许多空格:

The space will be preserved, and the result would look like below, many spaces between tokens:

 IF SUBSTR(WNAME3,M-1,1) = ')'             THEN                                        M = L;                                  ELSE                                        M = L - 1;

推荐答案

这正是我用于此目的的C#扩展方法:

This is the C# extension method I use for exactly this purpose:

public static string GetFullText(this ParserRuleContext context)
{
    if (context.Start == null || context.Stop == null || context.Start.StartIndex < 0 || context.Stop.StopIndex < 0)
        return context.GetText(); // Fallback

    return context.Start.InputStream.GetText(Interval.Of(context.Start.StartIndex, context.Stop.StopIndex));
}

由于您使用的是Java，因此必须对其进行翻译，但这应该很简单-API是相同的.

Since you're using java, you'll have to translate it, but it should be straightforward - the API is the same.

说明:获取第一个令牌，获取最后一个令牌，并从输入流中获取第一个令牌的第一个字符与最后一个令牌的最后一个字符之间的文本.

Explanation: Get the first token, get the last token, and get the text from the input stream between the first char of the first token and the last char of the last token.

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