Function: READ-WHITESPACE

Source

(defun read-whitespace (stream)
  (iterate
    (with part = (make-instance 'whitespace-part))
    (initially (setf (start-position part) (1+ (file-position stream))))
    (while (whitespacep (peek-char nil stream nil nil)))
    (read-char stream)
    (finally (setf (end-position part) (file-position stream)))
    (finally (return-from read-whitespace part))))