(in-package :phtml)

;;;; if* macro placed in the public domain by John Foderaro. See:
;;;; http://www.franz.com/~jkf/ifstar.txt

(defvar if*-keyword-list '("then" "thenret" "else" "elseif"))

(defmacro if* (&rest args)
   (do ((xx (reverse args) (cdr xx))
	(state :init)
	(elseseen nil)
	(totalcol nil)
	(lookat nil nil)
	(col nil))
       ((null xx)
	(cond ((eq state :compl)
	       `(cond ,@totalcol))
	      (t (error "if*: illegal form ~s" args))))
       (cond ((and (symbolp (car xx))
		   (member (symbol-name (car xx))
			   if*-keyword-list
			   :test #'string-equal))
	      (setq lookat (symbol-name (car xx)))))

       (cond ((eq state :init)
	      (cond (lookat (cond ((string-equal lookat "thenret")
				   (setq col nil
					 state :then))
				  (t (error
				      "if*: bad keyword ~a" lookat))))
		    (t (setq state :col
			     col nil)
		       (push (car xx) col))))
	     ((eq state :col)
	      (cond (lookat
		     (cond ((string-equal lookat "else")
			    (cond (elseseen
				   (error
				    "if*: multiples elses")))
			    (setq elseseen t)
			    (setq state :init)
			    (push `(t ,@col) totalcol))
			   ((string-equal lookat "then")
			    (setq state :then))
			   (t (error "if*: bad keyword ~s"
					      lookat))))
		    (t (push (car xx) col))))
	     ((eq state :then)
	      (cond (lookat
		     (error
		      "if*: keyword ~s at the wrong place " (car xx)))
		    (t (setq state :compl)
		       (push `(,(car xx) ,@col) totalcol))))
	     ((eq state :compl)
	      (cond ((not (string-equal lookat "elseif"))
		     (error "if*: missing elseif clause ")))
	      (setq state :init)))))

;DEFVAR-UNBOUND macro stolen from hunchentoot...
(eval-when (:compile-toplevel :execute :load-toplevel)
  (defmacro defvar-unbound (name &optional (doc-string ""))
    "Convenience macro to declare unbound special variables with a
documentation string."
    `(progn
      (defvar ,name)
      (setf (documentation ',name 'variable) ,doc-string))))