Identity Transform

The following, which owes much to James Clark's example in transform.htm from the Jade documentation and to Dan Speck's DSSSList post of October 10, 1997, performs a rudimentary SGML–SGML identity transformation. It does not regenerate the DOCTYPE declaration, nor does it handle processing instructions.

<!doctype style-sheet PUBLIC "-//James Clark//DTD DSSSL Style Sheet//EN">

(declare-flow-object-class element
  "UNREGISTERED::James Clark//Flow Object Class::element")
(declare-flow-object-class empty-element
  "UNREGISTERED::James Clark//Flow Object Class::empty-element")
(declare-characteristic preserve-sdata?
  "UNREGISTERED::James Clark//Characteristic::preserve-sdata?"
  #t)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Default rule
(default (output-element))

(define (output-element #!optional (node (current-node)))
  (if (node-property "must-omit-end-tag?" node)
      (make empty-element
	    attributes: (copy-attributes))
      (make element
	    attributes: (copy-attributes))))

(define (copy-attributes #!optional (nd (current-node)))
  (let loop ((atts (named-node-list-names (attributes nd))))
    (if (null? atts)
        '()
        (let* ((name (car atts))
               (value (attribute-string name nd)))
          (if value
              (cons (list name value)
                    (loop (cdr atts)))
              (loop (cdr atts)))))))