* src/buffer.c (Foverlays_at): Add argument `sorted'.

* doc/lispref/display.texi (Overlay Properties): Reword the doc of `priority'.
(Finding Overlays): Document new arg of `overlays-at'.
* lisp/obsolete/lucid.el (extent-at):
* lisp/htmlfontify.el (hfy-overlay-props-at): Use the new `sorted' arg of
overlays-at.
(hfy-fontify-buffer): Remove unused var `orig-ovls'.
* lisp/ps-def.el (ps-generate-postscript-with-faces1): Use the new `sorted'
arg of overlays-at.  Use `invisible-p'.

8 files changed, 41 insertions, 76 deletions

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 0246d1a44de..acbef6b9495 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -1475,8 +1475,10 @@ the buffer's undo list.
 
   Since more than one overlay can specify a property value for the
 same character, Emacs lets you specify a priority value of each
-overlay.  You should not make assumptions about which overlay will
-prevail when there is a conflict and they have the same priority.
+overlay.  In case two overlays have the same priority value, and one
+is nested in the other, then the inner one will have priority over the
+outer one.  If neither is nested in the other then you should not make
+assumptions about which overlay will prevail.
 
   These functions read and set the properties of an overlay:
 
@@ -1507,9 +1509,9 @@ of them:
 @table @code
 @item priority
 @kindex priority @r{(overlay property)}
-This property's value (which should be a non-negative integer)
-determines the priority of the overlay.  No priority, or @code{nil},
-means zero.
+This property's value determines the priority of the overlay.  No priority, or
+@code{nil}, means zero.  A non-nil and non-integer value has
+undefined behavior.
 
 The priority matters when two or more overlays cover the same
 character and both specify the same property; the one whose
@@ -1706,11 +1708,12 @@ Properties}.
 @node Finding Overlays
 @subsection Searching for Overlays
 
-@defun overlays-at pos
-This function returns a list of all the overlays that cover the
-character at position @var{pos} in the current buffer.  The list is in
-no particular order.  An overlay contains position @var{pos} if it
-begins at or before @var{pos}, and ends after @var{pos}.
+@defun overlays-at pos &optional sorted
+This function returns a list of all the overlays that cover the character at
+position @var{pos} in the current buffer.  If @var{sorted} is non-nil, the list
+is in decreasing order of priority, otherwise it is in no particular order.
+An overlay contains position @var{pos} if it begins at or before @var{pos}, and
+ends after @var{pos}.
 
 To illustrate usage, here is a Lisp function that returns a list of the
 overlays that specify property @var{prop} for the character at point:
diff --git a/etc/NEWS b/etc/NEWS
index db1dd43216b..6c6a8184ac6 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1219,6 +1219,8 @@ treated as regexps rather than literal strings.
 
 * Lisp Changes in Emacs 24.4
 
+** overlays-at can optionally sort its result by priority.
+
 +++
 ** The second argument of `eval' can now specify a lexical environment.
 
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index a77ccddb50b..74347bb5644 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,13 @@
+2014-04-15  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* ps-def.el (ps-generate-postscript-with-faces1): Use the new `sorted'
+	arg of overlays-at.  Use `invisible-p'.
+
+	* obsolete/lucid.el (extent-at):
+	* htmlfontify.el (hfy-overlay-props-at): Use the new `sorted' arg of
+	overlays-at.
+	(hfy-fontify-buffer): Remove unused var `orig-ovls'.
+
 2014-04-14  João Távora  <joaotavora@gmail.com>
 
 	* net/shr.el (shr-expand-url): Use `expand-file-name' for relative
diff --git a/lisp/htmlfontify.el b/lisp/htmlfontify.el
index 1282654899f..56887f39bef 100644
--- a/lisp/htmlfontify.el
+++ b/lisp/htmlfontify.el
@@ -1328,9 +1328,7 @@ return a `defface' style list of face properties instead of a face symbol."
 (defun hfy-overlay-props-at (p)
   "Grab overlay properties at point P.
 The plists are returned in descending priority order."
-  (sort (mapcar #'overlay-properties (overlays-at p))
-        (lambda (A B) (> (or (cadr (memq 'priority A)) 0) ;FIXME: plist-get?
-                    (or (cadr (memq 'priority B)) 0)))))
+ (mapcar #'overlay-properties (overlays-at p 'sorted)))
 
 ;; construct an assoc of (face-name . (css-name . "{ css-style }")) elements:
 (defun hfy-compile-stylesheet ()
@@ -1642,7 +1640,6 @@ FILE, if set, is the file name."
           (css-map                     nil)
           (invis-ranges                nil)
           (rovl                        nil)
-          (orig-ovls      (overlays-in (point-min) (point-max)))
           (rmin           (when mark-active (region-beginning)))
           (rmax           (when mark-active (region-end      ))) )
     (when (and mark-active
@@ -1664,12 +1661,6 @@ FILE, if set, is the file name."
     (set-buffer     html-buffer)
     ;; rip out props that could interfere with our htmlization of the buffer:
     (remove-text-properties (point-min) (point-max) hfy-ignored-properties)
-    ;; Apply overlay invisible spec
-    (setq orig-ovls
-          (sort orig-ovls
-                (lambda (A B)
-                  (> (or (cadr (memq 'priority (overlay-properties A))) 0)
-                     (or (cadr (memq 'priority (overlay-properties B))) 0)))))
     ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
     ;; at this point, html-buffer retains the fontification of the parent:
     ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
diff --git a/lisp/obsolete/lucid.el b/lisp/obsolete/lucid.el
index d3cb3f135d8..15f80652809 100644
--- a/lisp/obsolete/lucid.el
+++ b/lisp/obsolete/lucid.el
@@ -125,7 +125,7 @@ This is an XEmacs compatibility function."
 
 (defun extent-at (pos &optional object property before)
   (with-current-buffer (or object (current-buffer))
-    (let ((overlays (overlays-at pos)))
+    (let ((overlays (overlays-at pos 'sorted)))
       (when property
 	(let (filtered)
 	  (while overlays
@@ -133,14 +133,6 @@ This is an XEmacs compatibility function."
 		(setq filtered (cons (car overlays) filtered)))
 	    (setq overlays (cdr overlays)))
 	  (setq overlays filtered)))
-      (setq overlays
-	    (sort overlays
-		  (function (lambda (o1 o2)
-			      (let ((p1 (or (overlay-get o1 'priority) 0))
-				    (p2 (or (overlay-get o2 'priority) 0)))
-				(or (> p1 p2)
-				    (and (= p1 p2)
-					 (> (overlay-start o1) (overlay-start o2)))))))))
       (if before
 	  (nth 1 (memq before overlays))
 	(car overlays)))))
diff --git a/lisp/ps-def.el b/lisp/ps-def.el
index 06cef75cbbd..92a2e0b38cd 100644
--- a/lisp/ps-def.el
+++ b/lisp/ps-def.el
@@ -339,53 +339,11 @@
 	(setq position (min property-change overlay-change)
 	      before-string nil
 	      after-string nil)
-	;; The code below is not quite correct,
-	;; because a non-nil overlay invisible property
-	;; which is inactive according to the current value
-	;; of buffer-invisibility-spec nonetheless overrides
-	;; a face text property.
 	(setq face
-	      (cond ((let ((prop (get-text-property from 'invisible)))
-		       ;; Decide whether this invisible property
-		       ;; really makes the text invisible.
-		       (if (eq save-buffer-invisibility-spec t)
-			   (not (null prop))
-			 (or (memq prop save-buffer-invisibility-spec)
-			     (assq prop save-buffer-invisibility-spec))))
+	      (cond ((invisible-p from)
 		     'emacs--invisible--face)
-		    ((get-text-property from 'face))
+		    ((get-char-property from 'face))
 		    (t 'default)))
-	(let ((overlays (overlays-at from))
-	      (face-priority -1))	; text-property
-	  (while (and overlays
-		      (not (eq face 'emacs--invisible--face)))
-	    (let* ((overlay (car overlays))
-		   (overlay-invisible
-		    (overlay-get overlay 'invisible))
-		   (overlay-priority
-		    (or (overlay-get overlay 'priority) 0)))
-	      (and (> overlay-priority face-priority)
-		   (setq before-string
-			 (or (overlay-get overlay 'before-string)
-			     before-string)
-			 after-string
-			 (or (and (<= (overlay-end overlay) position)
-				  (overlay-get overlay 'after-string))
-			     after-string)
-			 face-priority overlay-priority
-			 face
-			 (cond
-			  ((if (eq save-buffer-invisibility-spec t)
-			       (not (null overlay-invisible))
-			     (or (memq overlay-invisible
-				       save-buffer-invisibility-spec)
-				 (assq overlay-invisible
-				       save-buffer-invisibility-spec)))
-			   'emacs--invisible--face)
-			  ((overlay-get overlay 'face))
-			  (t face)
-			  ))))
-	    (setq overlays (cdr overlays))))
 	;; Plot up to this record.
 	(and before-string
 	     (ps-plot-string before-string))
diff --git a/src/ChangeLog b/src/ChangeLog
index d0f46e5089f..1660b0f9148 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2014-04-15  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* buffer.c (Foverlays_at): Add argument `sorted'.
+
 2014-04-14  Eli Zaretskii  <eliz@gnu.org>
 
 	* insdel.c (invalidate_buffer_caches): When deleting or replacing
diff --git a/src/buffer.c b/src/buffer.c
index a1678951984..3e1359707cd 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -4168,9 +4168,10 @@ OVERLAY.  */)
 }
 
 
-DEFUN ("overlays-at", Foverlays_at, Soverlays_at, 1, 1, 0,
-       doc: /* Return a list of the overlays that contain the character at POS.  */)
-  (Lisp_Object pos)
+DEFUN ("overlays-at", Foverlays_at, Soverlays_at, 1, 2, 0,
+       doc: /* Return a list of the overlays that contain the character at POS.
+If SORTED is non-nil, then sort them by decreasing priority.  */)
+  (Lisp_Object pos, Lisp_Object sorted)
 {
   ptrdiff_t len, noverlays;
   Lisp_Object *overlay_vec;
@@ -4190,6 +4191,10 @@ DEFUN ("overlays-at", Foverlays_at, Soverlays_at, 1, 1, 0,
   noverlays = overlays_at (XINT (pos), 1, &overlay_vec, &len,
 			   NULL, NULL, 0);
 
+  if (!NILP (sorted))
+    noverlays = sort_overlays (overlay_vec, noverlays,
+			       WINDOWP (sorted) ? XWINDOW (sorted) : NULL);
+
   /* Make a list of them all.  */
   result = Flist (noverlays, overlay_vec);