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|
;;; This file implements spans in terms of overlays, for emacs19.
;;; Copyright (C) 1998 LFCS Edinburgh
;;; Author: Healfdene Goguen
;; Maintainer: LEGO Team <lego@dcs.ed.ac.uk>
;; $Log$
;; Revision 1.6 1998/06/02 15:36:51 hhg
;; Corrected comment about this being for emacs19.
;;
;; Revision 1.5 1998/05/29 09:50:10 tms
;; o outsourced indentation to proof-indent
;; o support indentation of commands
;; o replaced test of Emacs version with availability test of specific
;; features
;; o C-c C-c, C-c C-v and M-tab is now available in all buffers
;;
;; Revision 1.4 1998/05/21 17:27:41 hhg
;; Removed uninitialized os variable in spans-at-region.
;;
;; Revision 1.3 1998/05/21 08:28:52 hhg
;; Initialize 'before pointer in add-span-aux when last-span is nil.
;; Removed span-at-type.
;; Fixed bug in span-at-before, where (span-start span) may be nil.
;; Added spans-at-(point|region)[-prop], which fixes bug of C-c u at end
;; of buffer.
;;
;; Revision 1.2 1998/05/19 15:31:37 hhg
;; Added header and log message.
;; Fixed set-span-endpoints so it preserves invariant.
;; Changed add-span and remove-span so that they update last-span
;; correctly themselves, and don't take last-span as an argument.
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Bridging the emacs19/xemacs gulf ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; last-span represents a linked list of spans for each buffer.
;; It has the invariant of being ordered wrt the starting point of
;; the spans in the list, with detached spans at the end.
(defvar last-span nil
"Start of backwards-linked list of spans")
(make-variable-buffer-local 'last-span)
(defsubst span-start (span)
(overlay-start span))
(defsubst span-end (span)
(overlay-end span))
(defsubst span-property (span name)
(overlay-get span name))
(defsubst set-span-property (span name value)
(overlay-put span name value))
(defun span-lt (s t)
(or (not (span-start t))
(and (span-start s)
(< (span-start s) (span-start t)))))
(defun add-span (span)
(if last-span
(let ((l last-span) (cont (span-lt span l)) tmp)
(while (and l cont)
(if (not (span-property l 'before))
(setq cont nil)
(setq l (span-property l 'before))
(setq cont (span-lt span l))))
(setq tmp (span-property l 'before))
(set-span-property l 'before span)
(set-span-property span 'before tmp))
(setq last-span span)
(set-span-property span 'before nil))
span)
(defun make-span (start end)
(add-span (make-overlay start end)))
(defun remove-span-aux (span l)
(cond ((not l) (error "Bug: removing span from empty list"))
((eq span (span-property l 'before))
(set-span-property l 'before (span-property span 'before))
l)
(t (remove-span-aux span (span-property l 'before)))))
(defun remove-span (span)
(cond ((not last-span) (error "Bug: empty span list"))
((eq span last-span)
(setq last-span (span-property last-span 'before)))
(t (remove-span-aux span last-span))))
(defsubst detach-span (span)
(remove-span span)
(delete-overlay span)
(add-span span))
(defsubst delete-span (span)
(remove-span span)
(delete-overlay span))
;; The next two change ordering of list of spans:
(defsubst set-span-endpoints (span start end)
(remove-span span)
(move-overlay span start end)
(add-span span))
(defsubst set-span-start (span value)
(set-span-endpoints span value (span-end span)))
;; This doesn't affect invariant:
(defsubst set-span-end (span value)
(set-span-endpoints span (span-start span) value))
;; extent-at gives "smallest" extent at pos
;; we're assuming right now that spans don't overlap
(defun spans-at-point (pt)
(let ((overlays nil) (os nil))
(setq os (overlays-at pt))
(while os
(if (not (memq (car os) overlays))
(setq overlays (cons (car os) overlays)))
(setq os (cdr os)))
overlays))
(defun spans-at-region (start end)
(let ((overlays nil) (pos start))
(while (< pos end)
(setq overlays (append (spans-at-point pos) overlays))
(setq pos (next-overlay-change pos)))
overlays))
(defun spans-at-point-prop (pt prop)
(let ((f (cond
(prop (lambda (spans span)
(if (span-property span prop) (cons span spans)
spans)))
(t (lambda (spans span) (cons span spans))))))
(foldl f nil (spans-at-point pt))))
(defun spans-at-region-prop (start end prop)
(let ((f (cond
(prop (lambda (spans span)
(if (span-property span prop) (cons span spans)
spans)))
(t (lambda (spans span) (cons span spans))))))
(foldl f nil (spans-at-region start end))))
(defun span-at (pt prop)
(car (spans-at-point-prop pt prop)))
(defsubst delete-spans (start end prop)
(mapcar 'delete-span (spans-at-region-prop start end prop)))
(defun map-spans-aux (f l)
(cond (l (cons (funcall f l) (map-spans-aux f (span-property l 'before))))
(t ())))
(defsubst map-spans (f)
(map-spans-aux f last-span))
(defun find-span-aux (prop-p l)
(cond ((not l) ())
((funcall prop-p l) l)
(t (find-span-aux prop-p (span-property l 'before)))))
(defun find-span (prop-p)
(find-span-aux prop-p last-span))
(defun span-at-before (pt prop)
(let ((prop-pt-p
(cond (prop (lambda (span)
(let ((start (span-start span)))
(and start (> pt start)
(span-property span prop)))))
(t (lambda (span)
(let ((start (span-start span)))
(and start (> pt start))))))))
(find-span prop-pt-p)))
(defun prev-span (span prop)
(let ((prev-prop-p
(cond (prop (lambda (span) (span-property span prop)))
(t (lambda (span) t)))))
(find-span-aux prev-prop-p (span-property span 'before))))
(defun next-span-aux (prop spans)
(cond ((not spans) nil)
((span-property (car spans) prop) (car spans))
(t (next-span-aux prop (cdr spans)))))
;; overlays are [start, end)
(defun next-span (span prop)
(next-span-aux prop
(overlays-at (next-overlay-change (overlay-start span)))))
(provide 'span-overlay)
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