;;;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp; Base: 10 -*-
;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name:          ml.lisp
;;;; Purpose:       Markup Language Class
;;;; Programmer:    Kevin M. Rosenberg
;;;; Date Started:  Sep 2002
;;;;
;;;; This class defines functions for classes to allow display
;;;; in Text, HTML, and XML formats. This includes hyperlinking
;;;; capability and sub-objects. This is a re-write of ml-class.lisp
;;;  which used fairly difficult to port metaclass features.
;;;;
;;;; $Id: ml.lisp,v 1.2 2002/10/13 19:02:35 kevin Exp $
;;;;
;;;; This file, part of KMRCL, is Copyright (c) 2002 by Kevin M. Rosenberg
;;;;
;;;; KMRCL users are granted the rights to distribute and use this software
;;;; as governed by the terms of the Lisp Lesser GNU Public License
;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
;;;; *************************************************************************

(defpackage :kmrcl.ml
  (:use #:kmrcl #:common-lisp))


(in-package :kmrcl.ml)

(declaim (optimize (speed 3) (safety 1) (debug 3) (compilation-speed 0)))

;;; Design:
;;;  ml-class hold all formatting information for an object
;;;
;;; When a class is definited with the def-ml-class macro, a formatting
;;; object named _<name>-ml-fmt_ is created. Then, when a ml-class object
;;; is to be printed, the formatting object is referenced.

(defun initargs-def (fields)
  (loop for field in fields
	collect (intern (concatenate 'string ":" (symbol-name (car field))))
	collect nil))

(defun ml-fmt-name (name)
  (intern (concatenate 'string "_" (symbol-name name) "-ml-fmt_")))

(defun ml-fmt-def (name field-defs title types linked-fields subobjects)
  `(progn
     (defclass ,(ml-fmt-name name) (ml-fmt-class)
       ()
       (:default-initargs ,@(ml-fmt-initargs name field-defs title types linked-fields subobjects)))
     (make-instance ,(ml-fmt-name name))))

(defmacro def-ml-class (name (parent) field-defs &key title types linked-fields subobjects documentation)
  (let ((ml-fmt-name (ml-fmt-name name))
	(ml-fmt-def (ml-fmt-def name field-defs title types linked-fields subobjects))
	(initargs (initargs-def field-defs)))
    `(progn
       ,ml-fmt-def
       
       (defclass ,name (,parent)
	 ,field-defs
	 (:default-initargs ,initargs)
	 ,@(and documentation (list (list :documentation documentation)))
	 )
       )))

#+ignore
(def-ml-class urank (umlsclass)
  ((rank :type fixnum :initarg :rank :reader rank)
   (sab :type string :initarg :sab :reader sab)
   (tty :type string :initarg :tty :reader tty)
   (supres :type string :initarg :supres :reader supres))
  :title "Rank"
  :types ((rank :fixnum) (sab :string) (tty :string) (supres :string)))


   
(defclass ml-fmt-class ()
  ((title :initarg :title :type string :reader title
	  :documentation 
"Print Title for class")
   (fields :initarg :fields :reader fields
	   :documentation
"List of field lists for printing. Format is 
   ((fieldname type optional-formatter) ... )")
   (subobjects-lists 
    :initarg :subobjects-lists :reader subobjects-lists
    :documentation 
"List of fields that contain a list of subobjects objects.")
   (ref-fields 
    :initarg :ref-fields :type list :reader ref-field
    :documentation 
    "List of fields that can be referred to by browsers. 
Format is ((field-name field-lookup-func other-link-params) ...)")
   
   ;;; The remainder of these fields are calculated one time
   ;;; in finalize-inheritence.
   (value-func :initform nil :type function :reader value-func)
   (xmlvalue-func :initform nil :type function :reader xmlvalue-func)
   (fmtstr-text :initform nil :type string :reader fmtstr-text)
   (fmtstr-html :initform nil :type string :reader fmtstr-html)
   (fmtstr-xml :initform nil :type string :reader fmtstr-xml)
   (fmtstr-text-labels :initform nil :type string :reader fmtstr-text-labels)
   (fmtstr-html-labels :initform nil :type string :reader fmtstr-html-labels)
   (fmtstr-xml-labels :initform nil :type string :reader fmtstr-xml-labels)
   (fmtstr-html-ref :initform nil :type string :reader fmtstr-html-ref)
   (fmtstr-xml-ref :initform nil :type string :reader fmtstr-xml-ref)
   (fmtstr-html-ref-labels :initform nil :type string :reader fmtstr-html-ref-labels)
   (fmtstr-xml-ref-labels :initform nil :type string :reader fmtstr-xml-ref-labels)
   )
  (:default-initargs :title nil :fields nil :subobjects-lists nil :ref-fields nil)
  (:documentation "Class for Markup Language formatting objects."))


;;;; Class initialization function

(defun ml-fmt-initargs (name field-defs title types linked-fields subobjects)
  (let ((fmtstr-text "")
	(fmtstr-html "")
	(fmtstr-xml "")
	(fmtstr-text-labels "")
	(fmtstr-html-labels "")
	(fmtstr-xml-labels "")
	(fmtstr-html-ref "")
	(fmtstr-xml-ref "")
	(fmtstr-html-ref-labels "")
	(fmtstr-xml-ref-labels "")
	(first-field t)
	(value-func '())
	(xmlvalue-func '())
	(classname name)
	(linked-fields linked-fields))
    (declare (ignore classname))
    (dolist (f fields)
      (let ((name (car f))
	    (namestr (symbol-name (car f)))
	    (namestr-lower (string-downcase (symbol-name (car f))))
	    (type (cadr f))
	    (formatter (caddr f))
	    (value-fmt "~a")
	    (plain-value-func nil)
	    html-str xml-str html-label-str xml-label-str)
	
	(when (or (eql type :integer) (eql type :fixnum))
	  (setq value-fmt "~d"))
	
	(when (eql type :commainteger)
	  (setq value-fmt "~:d"))
	  
	(when (eql type :boolean)
	  (setq value-fmt "~a"))
	
	(if first-field
	      (setq first-field nil)
	  (progn
	    (string-append fmtstr-text " ")
	    (string-append fmtstr-html " ")
	    (string-append fmtstr-xml " ")
	    (string-append fmtstr-text-labels " ")
	    (string-append fmtstr-html-labels " ")
	    (string-append fmtstr-xml-labels " ")
	    (string-append fmtstr-html-ref " ")
	    (string-append fmtstr-xml-ref " ")
	    (string-append fmtstr-html-ref-labels " ")
	    (string-append fmtstr-xml-ref-labels " ")))
	
	(setq html-str value-fmt)
	(setq xml-str (concatenate 'string "<" namestr-lower ">" value-fmt "</" namestr-lower ">"))
	(setq html-label-str (concatenate 'string "<i>" namestr-lower "</i> " value-fmt))
	(setq xml-label-str (concatenate 'string "<label>" namestr-lower "</label> <" namestr-lower ">" value-fmt "</" namestr-lower ">"))
	
	(string-append fmtstr-text value-fmt)
	(string-append fmtstr-html html-str)
	(string-append fmtstr-xml xml-str)
	(string-append fmtstr-text-labels namestr-lower " " value-fmt)
	(string-append fmtstr-html-labels html-label-str)
	(string-append fmtstr-xml-labels xml-label-str)
	
	(if (find name linked-fields :key #'car)
	    (progn
	      (string-append fmtstr-html-ref "<~~a>" value-fmt "</~~a>")
	      (string-append fmtstr-xml-ref "<~~a>" value-fmt "</~~a>")
	      (string-append fmtstr-html-ref-labels "<i>" namestr-lower "</i> <~~a>" value-fmt "</~~a>")
	      (string-append fmtstr-xml-ref-labels "<label>" namestr-lower "</label> <~~a>" value-fmt "</~~a>"))
	  (progn
	    (string-append fmtstr-html-ref html-str)
	    (string-append fmtstr-xml-ref xml-str)
	    (string-append fmtstr-html-ref-labels html-label-str)
	    (string-append fmtstr-xml-ref-labels xml-label-str)))
	
	(if formatter
	    (setq plain-value-func 
		  (list `(,formatter (,(concat-symbol-pkg 
					:umlisp namestr) x))))
	    (setq plain-value-func 
		  (list `(,(concat-symbol-pkg 
			    :umlisp namestr) x))))
	(setq value-func (append value-func plain-value-func))
	
	(if (eql type :cdata)
	    (setq xmlvalue-func (append xmlvalue-func (list `(xml-cdata ,@plain-value-func))))
	  (setq xmlvalue-func (append xmlvalue-func plain-value-func)))
	))
    
      (setq value-func `(lambda (x) (values ,@value-func)))
      (setq value-func (compile nil (eval value-func)))
      (setq xmlvalue-func `(lambda (x) (values ,@xmlvalue-func)))
      (setq xmlvalue-func (compile nil (eval xmlvalue-func)))

      `(:title ,title
	:fmtstr-text ,fmtstr-text :fmtstr-html ,fmtstr-html
	:fmtstr-xml ,fmtstr-xml :fmtstr-text-labels ,fmtstr-text-labels
	:fmtstr-html-labels ,fmtstr-html-labels
	:fmtstr-xml-labels ,fmtstr-xml-labels
	:fmtstr-html-ref ,fmtstr-html-ref
	:fmtstr-xml-ref ,fmtstr-xml-ref
	:fmtstr-html-ref-labels ,fmtstr-html-ref-labels
	:fmtstr-xml-ref-labels ,fmtstr-xml-ref-labels
	:value-func ,value-func
	:xmlvalue-func ,xmlvalue-func)))


(defun %class-of (obj)
  #-(or cmu sbcl) (class-of obj)
  #+sbcl (sb-pcl:class-of obj)
  #+cmu (pcl:class-of obj))


(defun ml-class-fmtstr-text (obj)
  (slot-value (%class-of obj) 'fmtstr-text))

(defun ml-class-fmtstr-html (obj)
  (slot-value (%class-of obj) 'fmtstr-html))

(defun ml-class-fmtstr-xml (obj)
  (slot-value (%class-of obj) 'fmtstr-xml))

(defun ml-class-fmtstr-text-labels (obj)
  (slot-value (%class-of obj) 'fmtstr-text-labels))

(defun ml-class-fmtstr-html-labels (obj)
  (slot-value (%class-of obj) 'fmtstr-html-labels))

(defun ml-class-fmtstr-xml-labels (obj)
  (slot-value (%class-of obj) 'fmtstr-xml-labels))

(defun ml-class-value-func (obj)
  (slot-value (%class-of obj) 'value-func))

(defun ml-class-xmlvalue-func (obj)
  (slot-value (%class-of obj) 'xmlvalue-func))

(eval-when (:compile-toplevel :load-toplevel :execute)
(defun ml-class-title (obj)
  (awhen (slot-value (%class-of obj) 'title)
	    (if (consp it)
		(car it)
	      it))))

(defun ml-class-subobjects-lists (obj)
  (slot-value (%class-of obj) 'subobjects-lists))

(defun ml-class-linked-fields (obj)
  (slot-value (%class-of obj) 'linked-fields))

(defun ml-class-fields (obj)
  (slot-value (%class-of obj) 'fields))

(defun ml-class-fmtstr-html-ref (obj)
  (slot-value (%class-of obj) 'fmtstr-html-ref))

(defun ml-class-fmtstr-xml-ref (obj)
  (slot-value (%class-of obj) 'fmtstr-xml-ref))

(defun ml-class-fmtstr-html-ref-labels (obj)
  (slot-value (%class-of obj) 'fmtstr-html-ref-labels))

(defun ml-class-fmtstr-xml-ref-labels (obj)
  (slot-value (%class-of obj) 'fmtstr-xml-ref-labels))

;;; Class name functions

(defmethod ml-class-stdname ((name string))
  (string-downcase (subseq name :start 1)))
  
(defmethod ml-class-stdname ((cl standard-object))
  (string-downcase (subseq (class-name (%class-of cl)) :start 1)))
  
;;;; Generic Print functions

(defparameter *default-textformat* nil)
(defparameter *default-htmlformat* nil)
(defparameter *default-htmlrefformat* nil)
(defparameter *default-xmlformat* nil)
(defparameter *default-xmlrefformat* nil)
(defparameter *default-nullformat* nil)
(defparameter *default-init-format?* nil)

(defun make-format-instance (fmt)
  (unless *default-init-format?*
    (setq *default-textformat* (make-instance 'textformat))
    (setq *default-htmlformat* (make-instance 'htmlformat))
    (setq *default-htmlrefformat* (make-instance 'htmlrefformat))
    (setq *default-xmlformat* (make-instance 'xmlformat))
    (setq *default-xmlrefformat* (make-instance 'xmlrefformat))
    (setq *default-nullformat* (make-instance 'nullformat))
    (setq *default-init-format?* t))
  
  (case fmt
      (:text *default-textformat*)
      (:html *default-htmlformat*)
      (:htmlref *default-htmlrefformat*)
      (:xml  *default-xmlformat*)
      (:xmlref *default-xmlrefformat*)
      (:null *default-nullformat*)
      (otherwise *default-textformat*)))
    
;;;; Output format classes for print ml-classes

(defclass dataformat ()
  ((file-start-str :type string :initarg :file-start-str :reader file-start-str)
   (file-end-str :type string :initarg :file-end-str :reader file-end-str)
   (list-start-fmtstr :type string :initarg :list-start-fmtstr :reader list-start-fmtstr)
   (list-start-value-func :type function :initarg :list-start-value-func :reader list-start-value-func)
   (list-start-indent :initarg :list-start-indent :reader list-start-indent)
   (list-end-fmtstr :type string :initarg :list-end-fmtstr :reader list-end-fmtstr)
   (list-end-value-func :type function :initarg :list-end-value-func :reader list-end-value-func)
   (list-end-indent :initarg :list-end-indent :reader list-end-indent)
   (obj-start-fmtstr :type string :initarg :obj-start-fmtstr :reader obj-start-fmtstr)
   (obj-start-value-func :initarg :obj-start-value-func :reader obj-start-value-func)
   (obj-start-indent :initarg :obj-start-indent :reader obj-start-indent)
   (obj-end-fmtstr :type string :initarg :obj-end-fmtstr :reader obj-end-fmtstr)
   (obj-end-value-func :initarg :obj-end-value-func :reader obj-end-value-func)
   (obj-end-indent :initarg :obj-end-indent :reader obj-end-indent)
   (obj-data-indent :initarg :obj-data-indent :reader obj-data-indent)
   (obj-data-fmtstr :initarg :obj-data-fmtstr :reader  obj-data-fmtstr)
   (obj-data-fmtstr-labels :initarg :obj-data-fmtstr-labels :reader  obj-data-fmtstr-labels)
   (obj-data-end-fmtstr :initarg :obj-data-end-fmtstr :reader obj-data-end-fmtstr)
   (obj-data-value-func :initarg :obj-data-value-func :reader obj-data-value-func)
   (link-ref :initarg :link-ref :reader link-ref))
  (:default-initargs :file-start-str nil :file-end-str nil :list-start-fmtstr nil :list-start-value-func nil
		     :list-start-indent nil :list-end-fmtstr nil :list-end-value-func nil :list-end-indent nil
		     :obj-start-fmtstr nil :obj-start-value-func nil :obj-start-indent nil
		     :obj-end-fmtstr nil :obj-end-value-func nil :obj-end-indent nil
		     :obj-data-indent nil :obj-data-fmtstr nil :obj-data-fmtstr-labels nil :obj-data-end-fmtstr nil
		     :obj-data-value-func nil :link-ref nil)
  (:documentation "Parent for all dataformat objects"))

(defclass binaryformat (dataformat)
  ())

(defclass nullformat (dataformat)
  ())

(defun text-list-start-value-func (obj nitems)
  (values (ml-class-title obj) nitems))

(defclass textformat (dataformat) 
  ()	
  (:default-initargs :list-start-fmtstr "~a~P:~%"
    :list-start-value-func #'text-list-start-value-func
    :list-start-indent t
    :obj-data-indent t
    :obj-data-fmtstr #'ml-class-fmtstr-text
    :obj-data-fmtstr-labels #'ml-class-fmtstr-text-labels
    :obj-data-end-fmtstr "~%"
    :obj-data-value-func #'ml-class-value-func))

(defclass htmlformat (textformat) 
  ()
  (:default-initargs :file-start-str "<html><body>~%"
    :file-end-str "</body><html>~%"
    :list-start-indent t
    :list-start-fmtstr "<p><b>~a~P:</b></p><ul>~%"
    :list-start-value-func #'text-list-start-value-func
    :list-end-fmtstr "</ul>~%"
    :list-end-indent t
    :list-end-value-func #'identity
    :obj-start-indent t
    :obj-start-fmtstr "<li>"
    :obj-start-value-func #'identity
    :obj-end-indent  t
    :obj-end-fmtstr  "</li>~%"
    :obj-end-value-func #'identity
    :obj-data-indent t
    :obj-data-fmtstr #'ml-class-fmtstr-html-labels
    :obj-data-fmtstr-labels #'ml-class-fmtstr-html-labels
    :obj-data-value-func #'ml-class-value-func))


(defun class-name-of (obj)
  (string-downcase (class-name (%class-of obj))))

(defun xmlformat-list-end-value-func (x)
  (format nil "~alist" (string-downcase (class-name (%class-of x)))))

(defun xmlformat-list-start-value-func (x nitems) 
  (values (format nil "~alist" (string-downcase (class-name (%class-of x)))) (ml-class-title x) nitems))

(defclass xmlformat (textformat) 
  ()
  (:default-initargs :file-start-str "" ; (std-xml-header)
    :list-start-indent  t
    :list-start-fmtstr "<~a><title>~a~p:</title> ~%"
    :list-start-value-func #'xmlformat-list-start-value-func
    :list-end-indent  t
    :list-end-fmtstr "</~a>~%"
    :list-end-value-func #'xmlformat-list-end-value-func
    :obj-start-fmtstr "<~a>"
    :obj-start-value-func #'class-name-of
    :obj-start-indent t
    :obj-end-fmtstr "</~a>~%"
    :obj-end-value-func #'class-name-of
    :obj-end-indent nil
    :obj-data-indent nil
    :obj-data-fmtstr #'ml-class-fmtstr-xml
    :obj-data-fmtstr-labels #'ml-class-fmtstr-xml-labels
    :obj-data-value-func #'ml-class-xmlvalue-func))

(defclass link-ref ()
  ((fmtstr :type function :initarg :fmtstr :accessor fmtstr)
   (fmtstr-labels :type function :initarg :fmtstr-labels :accessor fmtstr-labels)
   (page-name :type string :initarg :page-name :accessor page-name)
   (href-head :type string :initarg :href-head :accessor href-head)
   (href-end :type string :initarg :href-end :accessor href-end)
   (ampersand :type string :initarg :ampersand :accessor ampersand))
  (:default-initargs :fmtstr nil 
    :fmtstr-labels nil 
    :page-name "disp-func1" 
    :href-head nil :href-end nil :ampersand nil)
  (:documentation "Formatting for a linked reference"))

(defclass html-link-ref (link-ref)
  ()
  (:default-initargs :fmtstr #'ml-class-fmtstr-html-ref  
    :fmtstr-labels #'ml-class-fmtstr-html-ref-labels
    :href-head "a href=" 
    :href-end "a" 
    :ampersand "&"))

(defclass xml-link-ref (link-ref)
  ()
  (:default-initargs :fmtstr #'ml-class-fmtstr-xml-ref 
    :fmtstr-labels #'ml-class-fmtstr-xml-ref-labels
    :href-head "xmllink xlink:type=\"simple\" xlink:href=" 
    :href-end "xmllink" 
    :ampersand "&amp;"))


(defclass htmlrefformat (htmlformat)
  ()
  (:default-initargs :link-ref (make-instance 'html-link-ref)))

(defclass xmlrefformat (xmlformat)
  ()
  (:default-initargs :link-ref (make-instance 'xml-link-ref)))


;;; File Start and Ends

(defmethod fmt-file-start ((fmt dataformat) (s stream)))

(defmethod fmt-file-start ((fmt textformat) (s stream))
  (aif (file-start-str fmt)
      (format s it)))

(defmethod fmt-file-end ((fmt textformat) (s stream))
  (aif (file-end-str fmt)
	  (format s it)))

;;; List Start and Ends

(defmethod fmt-list-start (x (fmt textformat) (s stream) &optional (indent 0) (num-items 1))
  (if (list-start-indent fmt)
      (indent-spaces indent s))
  (aif (list-start-fmtstr fmt)
	  (apply #'format s it
		 (multiple-value-list
		  (funcall (list-start-value-func fmt) x num-items)))))

(defmethod fmt-list-end (x (fmt textformat) (s stream) &optional (indent 0) (num-items 1))
  (declare (ignore num-items))
  (if (list-end-indent fmt)
      (indent-spaces indent s))
  (aif (list-end-fmtstr fmt)
	  (apply #'format s it
		 (multiple-value-list
		  (funcall (list-end-value-func fmt) x)))))

;;; Object Start and Ends

(defmethod fmt-obj-start (x (fmt textformat) (s stream) &optional (indent 0))
  (if (obj-start-indent fmt)
      (indent-spaces indent s))
  (aif (obj-start-fmtstr fmt)
	  (apply #'format s it
		 (multiple-value-list
		  (funcall (obj-start-value-func fmt) x)))))

(defmethod fmt-obj-end (x (fmt textformat) (s stream) &optional (indent 0))
  (if (obj-end-indent fmt)
      (indent-spaces indent s))
  (aif (obj-end-fmtstr fmt)
	  (apply #'format s it
		 (multiple-value-list
		  (funcall (obj-end-value-func fmt) x)))))
  
;;; Object Data 

(defmethod make-link-start (obj (ref link-ref) fieldname fieldfunc fieldvalue refvars)
  (declare (ignore obj fieldname))
  (format nil "~a\"~a?func=~a~akey=~a~a\"" 
	  (href-head ref) (make-url (page-name ref)) fieldfunc 
	  (ampersand ref) fieldvalue
	  (if refvars
	      (let ((varstr ""))
		(dolist (var refvars)
		  (string-append varstr (format nil "~a~a=~a" 
						(ampersand ref) (car var) (cadr var))))
		varstr)
	    "")))

(defmethod make-link-end (obj (ref link-ref) fieldname)
  (declare (ignore obj fieldname))
  (format nil "~a" (href-end ref))
  )

(defmethod fmt-obj-data (x (fmt textformat) s
			 &optional (indent 0) (label nil) (refvars nil))
  (if (obj-data-indent fmt)
      (indent-spaces indent s))
  (if (link-ref fmt)
      (fmt-obj-data-with-ref x fmt s label refvars)
    (fmt-obj-data-plain x fmt s label))
  (aif (obj-data-end-fmtstr fmt)
       (format s it)))

(defmethod fmt-obj-data-plain (x (fmt textformat) s label)
  (if label
      (apply #'format s
	     (funcall (obj-data-fmtstr-labels fmt) x)
	     (multiple-value-list 
	      (funcall (funcall (obj-data-value-func fmt) x) x)))
    (apply #'format s (funcall (obj-data-fmtstr fmt) x)
	   (multiple-value-list
	    (funcall (funcall (obj-data-value-func fmt) x) x)))))

(defmethod fmt-obj-data-with-ref (x (fmt textformat) s label refvars)
  (let ((refstr (make-ref-data-str x fmt label))
	(refvalues nil)
	(field-values 
	 (multiple-value-list
	  (funcall (funcall (obj-data-value-func fmt) x) x))))
    
    ;; make list of reference link fields for printing to refstr template
    (dolist (field (ml-class-linked-fields x))
      (let ((link-start 
	     (make-link-start x (link-ref fmt) (car field) (cadr field)
			      (nth (position (car field) (ml-class-fields x) :key #'car) field-values)  
			      (append (caddr field) refvars)))
	    (link-end (make-link-end x (link-ref fmt) (car field))))
	(push link-start refvalues)
	(push link-end refvalues)))
    (setq refvalues (nreverse refvalues))
    
    (apply #'format s refstr refvalues)))
  
(defmethod obj-data (x)
  "Returns the objects data as a string. Used by common-graphics outline function"
  (let ((fmt (make-format-instance :text)))
    (apply #'format nil (funcall (obj-data-fmtstr fmt) x)
	   (multiple-value-list 
	    (funcall (funcall (obj-data-value-func fmt) x) x)))))

(defmethod make-ref-data-str (x (fmt textformat) &optional (label nil))
  "Return fmt string for that contains ~a slots for reference link start and end"
  (unless (link-ref fmt)
    (error "fmt does not contain a link-ref"))
  (let ((refstr 
	 (if label
	     (apply #'format nil (funcall (fmtstr-labels (link-ref fmt)) x)
		    (multiple-value-list
		      (funcall (funcall (obj-data-value-func fmt) x) x)))
	   (apply #'format nil (funcall (fmtstr (link-ref fmt)) x)
		  (multiple-value-list (funcall (funcall (obj-data-value-func fmt) x) x))))))
    refstr))
  
;;; Display method for objects


(defmethod load-all-subobjects (objs)
  "Load all subobjects if they have not already been loaded."
  (when objs
    (let ((objlist (mklist objs)))
      (dolist (obj objlist)
        (awhen (ml-class-subobjects-lists obj)  ;; access list of functions
          (dolist (child-obj it)   ;; for each child function
            (awhen (funcall (car child-obj) obj)
              (load-all-subobjects it))))))
    objs))

(defmethod output-ml-class (objs (fmt dataformat) (strm stream) 
			    &optional (label nil) (english-only-function nil)
				      (indent 0) (subobjects nil) (refvars nil))
  "Display a single or list of ml-class instances and their subobjects"
  (when objs
    (setq objs (mklist objs))
    (let ((nobjs (length objs)))
      (fmt-list-start (car objs) fmt strm indent nobjs)
      (dolist (obj objs)
        (unless (and english-only-function (not (funcall english-only-function obj)))
          (fmt-obj-start obj fmt strm indent)
          (fmt-obj-data obj fmt strm (1+ indent) label refvars)
          (if subobjects
              (awhen (ml-class-subobjects-lists obj)  ;; access list of functions
                        (dolist (child-obj it)   ;; for each child function
                          (awhen (funcall (car child-obj) obj) ;; access set of child objects
                                    (output-ml-class it fmt strm label 
                                                     english-only-function
                                                     (1+ indent) subobjects refvars)))))
          (fmt-obj-end obj fmt strm indent)))
      (fmt-list-end (car objs) fmt strm indent nobjs))
    t))

(defun display-ml-class (objs &key (os *standard-output*) (format :text)
				(label nil) (english-only-function nil) (subobjects nil)
				(file-wrapper t) (refvars nil))
  "EXPORTED Function: displays a ml-class. Simplies call to output-ml-class"
  (let ((fmt (make-format-instance format)))
    (if file-wrapper
	(fmt-file-start fmt os))
    (when objs
      (output-ml-class objs fmt os label english-only-function 0 subobjects refvars))
    (if file-wrapper
	(fmt-file-end fmt os)))
  objs)