Currently ANTLR does not create templates for you automatically when you use output=template option. This is because, when I first implemented it, I had no idea what the right answer was here. I did not know how to deal with whitespace and so on. I think I have the answer now. First, let me remind you that output=AST builds a completely flat tree given no instructions to the contrary. Similarly, the template output should reproduce the input given no instructions. Some cases seem obvious. What should the output template be for this rule?
| No Format |
|---|
d : 'int' ID ';' ;
|
The answer is not just concatenating the tokens because of whitespace. I tried a simple mechanism that added a little bit of code to each token and rule reference. The code snippet would copy the token object into some default template, which the user can specify by overriding a method call getDefaultTemplate(String ruleName).