Fast save_excursion_save and save_excursion_restore.

* lisp.h (struct Lisp_Excursion): New data type.
(PVEC_EXCURSION): New pseudovector type.
(XEXCURSION, XSETEXCURSION, EXCURSIONP): Convenient macros
to deal with it.  Adjust comments.
(init_marker, attach_marker): New prototype.
(unchain_marker): Adjust prototype.
* marker.c (attach_marker): Change to global.
(init_marker): New function.
* alloc.c (Fmake_marker, build_marker): Use it.
(build_marker): More easserts.
(mark_object): Handle struct Lisp_Excursion.
* editfns.c (save_excursion_save, save_excursion_restore):
Reimplement to use struct Lisp_Excursion.  Add comments.

1 files changed, 20 insertions, 1 deletions

diff --git a/src/marker.c b/src/marker.c
index 0a93f4c180f..d63947d8c31 100644
--- a/src/marker.c
+++ b/src/marker.c
@@ -425,9 +425,28 @@ Returns nil if MARKER points nowhere.  */)
   return Qnil;
 }
 
+/* Initialize just allocated Lisp_Marker.  */
+
+void
+init_marker (struct Lisp_Marker *m, struct buffer *b,
+	     ptrdiff_t charpos, ptrdiff_t bytepos, int type)
+{
+  m->buffer = b;
+  m->charpos = charpos;
+  m->bytepos = bytepos;
+  m->insertion_type = type;
+  if (b)
+    {
+      m->next = BUF_MARKERS (b);
+      BUF_MARKERS (b) = m;
+    }
+  else
+    m->next = NULL;
+}
+
 /* Change M so it points to B at CHARPOS and BYTEPOS.  */
 
-static inline void
+void
 attach_marker (struct Lisp_Marker *m, struct buffer *b,
 	       ptrdiff_t charpos, ptrdiff_t bytepos)
 {