anchor.diff:      ;
   
   br_instruction returns [I0Instruction *retval]
  -    : 'br' ':' 
  +    : 'br' ':'
       {
           $retval = new I0Instruction();
           $retval->OpCode = I0Instruction::B;
       }
  -    ( 
  +    (
           'j' r1 = br_relative imm1 = immediate_operand
           {
               $retval->JumpMode = I0Instruction::J;
  
positive.code: grammar I0;
  
  options 
  {
      language    = C;
      backtrack   = true;
  
negative.code: IDENTIFIER
      :   LETTER (LETTER|'0'..'9')*
      ;
  
  
  
  fragment
  