question: protected void warning ( int line , int column , String msg ) throws LexerException { if ( warnings . contains ( Warning . ERROR ) ) error ( line , column , msg ) ; else if ( listener != null ) listener . handleWarning ( source , line , column , msg ) ; else throw new LexerException ( "Warning at " + line + ":" + column + ": " + msg ) ; }
target:  Handles a warning. If a PreprocessorListener is installed, it receives the warning. Otherwise, an exception is thrown.