title: changing text of rule in antlr4 using setText
body: <p>I want to change every entry in csv file to 'BlahBlah'
  For that I have antlr grammar as</p>
  
  <pre><code>grammar CSV;
  
  file : hdr row* row1;
  hdr : row;
  
  row :  field (',' value1=field)* '\r'? '\n'; // '\r' is optional at the end of a row of CSV file ..
  
  row1 :  field (',' field)* '\r'? '\n'?;
  
  field 
        :  TEXT
      {
          $setText("BlahBlah");
      }
        |  STRING 
        | 
        ;
  TEXT : ~[,\n\r"]+ ;
  STRING : '"' ('""' | ~'"')* '"' ;
  </code></pre>
  
  <p>But when I run this on antlr4 </p>
  
  <pre><code>error(63): CSV.g4:13:3: unknown attribute reference setText in $setText
  make: *** [run] Error 1
  </code></pre>
  
  <p>why is setText not supported in antlr4 and is there any other alternative to replace text?</p>