javacc笔记2

void basic_expr() :
  {}
  {
    <ID> "(" expr() ")" // Choice 1
  |
    "(" expr() ")"  // Choice 2
  |
    "new" <ID>    // Choice 3
  }

 
The choice determination algorithm works as follows:
 


  if (next token is <ID>) {
    choose Choice 1
  } else if (next token is "(") {
    choose Choice 2
  } else if (next token is "new") {
    choose Choice 3
  } else {
    produce an error message
  }