How to preserve whitespace when we use text attribute in Antlr4 - antlr

Question

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";
In this case, I want to transform it into:
if (!(L>40){
if (A=20)
put "hello";
}
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("}");
}
}
But the result looks like:
if(!(L>40))
{
ifA=20put"hello";
}
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
Update: If I add
SPACE: [ ] -> channel(HIDDEN);
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;

Answer 1

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

Answer 2

#Lucas solution, but in java in case you have troubles in translating:
private String getFullText(ParserRuleContext context) {
if (context.start == null || context.stop == null || context.start.getStartIndex() < 0 || context.stop.getStopIndex() < 0)
return context.getText();
return context.start.getInputStream().getText(Interval.of(context.start.getStartIndex(), context.stop.getStopIndex()));
}

Answer 3

Looks like InputStream is not always updated after removeLastChild/addChild operations. This solution helped me for one grammar, but it doesn't work for another.
Works for this grammar.
Doesn't work for modern groovy grammar (for some reason inputStream.getText contains old text).
I am trying to implement function name replacement like this:
enterPostfixExpression(ctx: PostfixExpressionContext) {
// Get identifierContext from ctx
...
const token = CommonTokenFactory.DEFAULT.createSimple(GroovyParser.Identifier, 'someNewFnName');
const node = new TerminalNode(token);
identifierContext.removeLastChild();
identifierContext.addChild(node);
UPD: I used visitor pattern for the first implementation