;; span.el	Datatype of "spans" for Proof General.
;;
;; Copyright (C) 1998 LFCS Edinburgh
;; Author:    Healfdene Goguen
;; License:   GPL (GNU GENERAL PUBLIC LICENSE)
;;
;; $Id$
;;
;; Spans are our abstraction of extents/overlays.
;;

(eval-and-compile
  (if (featurep 'xemacs)
      (require 'span-extent))
  (if (not (featurep 'xemacs))
      (require 'span-overlay)))

;;
;; Generic functions built on low-level concrete ones.
;; 

(defsubst span-delete-spans (start end prop)
  "Delete all spans between START and END with property PROP set."
  (span-mapcar-spans 'span-delete start end prop))

(defsubst span-property-safe (span name)
  "Like span-property, but return nil if SPAN is nil."
  (and span (span-property span name)))
  
(defsubst span-set-start (span value)
  "Set the start point of SPAN to VALUE."
  (span-set-endpoints span value (span-end span)))

(defsubst span-set-end (span value)
  "Set the end point of SPAN to VALUE."
  (span-set-endpoints span (span-start span) value))

(provide 'span)
;; span.el ends here.