question: private static TokenSpec findMaximalIdCharSeq ( String line , int pos ) { int left = pos ; int rt = pos ; left = pos ; while ( Character . isLetterOrDigit ( line . charAt ( left - 1 ) ) || line . charAt ( left - 1 ) == '_' ) { left -- ; } while ( Character . isLetterOrDigit ( line . charAt ( rt ) ) || line . charAt ( rt ) == '_' ) { rt ++ ; } if ( left == rt ) { return null ; } else { return new TokenSpec ( line . substring ( left , rt ) , left , rt ) ; } }
target:  Returns the TokenSpec of the largest token containing digits, letters, and "_" characters containing position pos.  Returns null if that would be an empty token.