[Emacs-diffs] /srv/bzr/emacs/trunk r108902: * buffer.c (unchain_overlay): Simplify. Add comment.

[Dmitry Antipov]

------------------------------------------------------------
revno: 108902
committer: Dmitry Antipov <address@hidden>
branch nick: trunk
timestamp: Fri 2012-07-06 11:34:37 +0400
message:
  * buffer.c (unchain_overlay): Simplify.  Add comment.
  * marker.c (unchain_marker): Simplify.  Fix comments.
modified:
  src/ChangeLog
  src/buffer.c
  src/marker.c

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2012-07-06 05:07:44 +0000
+++ b/src/ChangeLog     2012-07-06 07:34:37 +0000
@@ -1,5 +1,10 @@
 2012-07-06  Dmitry Antipov  <address@hidden>
 
+       * buffer.c (unchain_overlay): Simplify.  Add comment.
+       * marker.c (unchain_marker): Simplify. Fix comments.
+
+2012-07-06  Dmitry Antipov  <address@hidden>
+
        Introduce fast path for the widely used marker operation.
        * alloc.c (build_marker): New function.
        * lisp.h (build_marker): New prototype.

=== modified file 'src/buffer.c'
--- a/src/buffer.c      2012-07-06 05:07:44 +0000
+++ b/src/buffer.c      2012-07-06 07:34:37 +0000
@@ -3672,18 +3672,17 @@
   ++BUF_OVERLAY_MODIFF (buf);
 }
 
-
+/* Remove OVERLAY from LIST.  */
+
 static struct Lisp_Overlay *
 unchain_overlay (struct Lisp_Overlay *list, struct Lisp_Overlay *overlay)
 {
-  struct Lisp_Overlay *tmp, *prev;
-  for (tmp = list, prev = NULL; tmp; prev = tmp, tmp = tmp->next)
-    if (tmp == overlay)
+  register struct Lisp_Overlay *tail, **prev = &list;
+
+  for (tail = list; tail; prev = &tail->next, tail = *prev)
+    if (tail == overlay)
       {
-       if (prev)
-         prev->next = tmp->next;
-       else
-         list = tmp->next;
+       *prev = overlay->next;
        overlay->next = NULL;
        break;
       }

=== modified file 'src/marker.c'
--- a/src/marker.c      2012-07-06 05:07:44 +0000
+++ b/src/marker.c      2012-07-06 07:34:37 +0000
@@ -672,59 +672,47 @@
   return marker;
 }
 
-/* Remove MARKER from the chain of whatever buffer it is in.
-   Leave it "in no buffer".
-
-   This is called during garbage collection,
-   so we must be careful to ignore and preserve mark bits,
-   including those in chain fields of markers.  */
+/* Remove MARKER from the chain of whatever buffer it is in,
+   leaving it points to nowhere.  This is called during garbage
+   collection, so we must be careful to ignore and preserve
+   mark bits, including those in chain fields of markers.  */
 
 void
 unchain_marker (register struct Lisp_Marker *marker)
 {
-  register struct Lisp_Marker *tail, *prev, *next;
-  register struct buffer *b;
-
-  b = marker->buffer;
-  if (b == 0)
-    return;
-
-  if (EQ (BVAR (b, name), Qnil))
-    abort ();
-
-  marker->buffer = 0;
-
-  tail = BUF_MARKERS (b);
-  prev = NULL;
-  while (tail)
+  register struct buffer *b = marker->buffer;
+
+  if (b)
     {
-      next = tail->next;
-
-      if (marker == tail)
-       {
-         if (!prev)
-           {
-             BUF_MARKERS (b) = next;
-             /* Deleting first marker from the buffer's chain.  Crash
-                if new first marker in chain does not say it belongs
-                to the same buffer, or at least that they have the same
-                base buffer.  */
-             if (next && b->text != next->buffer->text)
-               abort ();
-           }
-         else
-           prev->next = next;
-         /* We have removed the marker from the chain;
-            no need to scan the rest of the chain.  */
-         return;
-       }
-      else
-       prev = tail;
-      tail = next;
+      register struct Lisp_Marker *tail, **prev;
+
+      /* No dead buffers here.  */
+      eassert (!NILP (BVAR (b, name)));
+
+      marker->buffer = NULL;
+      prev = &BUF_MARKERS (b);
+
+      for (tail = BUF_MARKERS (b); tail; prev = &tail->next, tail = *prev)
+       if (marker == tail)
+         {
+           if (*prev == BUF_MARKERS (b))
+             {
+               /* Deleting first marker from the buffer's chain.  Crash 
+                  if new first marker in chain does not say it belongs
+                  to the same buffer, or at least that they have the same
+                  base buffer.  */
+               if (tail->next && b->text != tail->next->buffer->text)
+                 abort ();
+             }
+           *prev = tail->next;
+           /* We have removed the marker from the chain;
+              no need to scan the rest of the chain.  */
+           break;
+         }
+
+      /* Error if marker was not in it's chain.  */
+      eassert (tail != NULL);
     }
-
-  /* Marker was not in its chain.  */
-  abort ();
 }
 
 /* Return the char position of marker MARKER, as a C integer.  */