--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/extents.c	Mon Aug 13 08:45:50 2007 +0200
@@ -0,0 +1,6885 @@
+/* Copyright (c) 1994, 1995 Free Software Foundation, Inc.
+   Copyright (c) 1995 Sun Microsystems, Inc.
+   Copyright (c) 1995, 1996 Ben Wing.
+
+This file is part of XEmacs.
+
+XEmacs is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+XEmacs is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with XEmacs; see the file COPYING.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* Synched up with: Not in FSF. */
+
+/* This file has been Mule-ized. */
+
+/* Written by Ben Wing <wing@666.com>.
+
+   [Originally written by some people at Lucid.
+   Hacked on by jwz.
+   Start/end-open stuff added by John Rose (john.rose@eng.sun.com).
+   Rewritten from scratch by Ben Wing, December 1994.] */
+
+/* Commentary:
+
+   Extents are regions over a buffer, with a start and an end position
+   denoting the region of the buffer included in the extent.  In
+   addition, either end can be closed or open, meaning that the endpoint
+   is or is not logically included in the extent.  Insertion of a character
+   at a closed endpoint causes the character to go inside the extent;
+   insertion at an open endpoint causes the character to go outside.
+
+   Extent endpoints are stored using memory indices (see insdel.c),
+   to minimize the amount of adjusting that needs to be done when
+   characters are inserted or deleted.
+
+   (Formerly, extent endpoints at the gap could be either before or
+   after the gap, depending on the open/closedness of the endpoint.
+   The intent of this was to make it so that insertions would
+   automatically go inside or out of extents as necessary with no
+   further work needing to be done.  It didn't work out that way,
+   however, and just ended up complexifying and buggifying all the
+   rest of the code.)
+
+   Extents are compared using memory indices.  There are two orderings
+   for extents and both orders are kept current at all times.  The normal
+   or "display" order is as follows:
+
+   Extent A is "less than" extent B, that is, earlier in the display order,
+   if:    A-start < B-start,
+   or if: A-start = B-start, and A-end > B-end
+
+   So if two extents begin at the same position, the larger of them is the
+   earlier one in the display order (EXTENT_LESS is true).
+
+   For the e-order, the same thing holds: Extent A is "less than" extent B
+   in e-order, that is, later in the buffer,
+   if:    A-end < B-end,
+   or if: A-end = B-end, and A-start > B-start
+
+   So if two extents end at the same position, the smaller of them is the
+   earlier one in the e-order (EXTENT_E_LESS is true).
+
+   The display order and the e-order are complementary orders: any
+   theorem about the display order also applies to the e-order if you
+   swap all occurrences of "display order" and "e-order", "less than"
+   and "greater than", and "extent start" and "extent end".
+
+   Extents can be zero-length, and will end up that way if their endpoints
+   are explicitly set that way or if their detachable property is nil
+   and all the text in the extent is deleted. (The exception is open-open
+   zero-length extents, which are barred from existing because there is
+   no sensible way to define their properties.  Deletion of the text in
+   an open-open extent causes it to be converted into a closed-open
+   extent.)  Zero-length extents are primarily used to represent
+   annotations, and behave as follows:
+
+   1) Insertion at the position of a zero-length extent expands the extent
+   if both endpoints are closed; goes after the extent if it is closed-open;
+   and goes before the extent if it is open-closed.
+
+   2) Deletion of a character on a side of a zero-length extent whose
+   corresponding endpoint is closed causes the extent to be detached if
+   it is detachable; if the extent is not detachable or the corresponding
+   endpoint is open, the extent remains in the buffer, moving as necessary.
+
+   Note that closed-open, non-detachable zero-length extents behave exactly
+   like markers and that open-closed, non-detachable zero-length extents
+   behave like the "point-type" marker in Mule.
+
+
+   #### The following information is wrong in places.
+
+   More about the different orders:
+   --------------------------------
+
+   The extents in a buffer are ordered by "display order" because that
+   is that order that the redisplay mechanism needs to process them in.
+   The e-order is an auxiliary ordering used to facilitate operations
+   over extents.  The operations that can be performed on the ordered
+   list of extents in a buffer are
+
+   1) Locate where an extent would go if inserted into the list.
+   2) Insert an extent into the list.
+   3) Remove an extent from the list.
+   4) Map over all the extents that overlap a range.
+
+   (4) requires being able to determine the first and last extents
+   that overlap a range.
+
+   NOTE: "overlap" is used as follows:
+
+   -- two ranges overlap if they have at least one point in common.
+      Whether the endpoints are open or closed makes a difference here.
+   -- a point overlaps a range if the point is contained within the
+      range; this is equivalent to treating a point P as the range
+      [P, P].
+   -- In the case of an *extent* overlapping a point or range, the
+      extent is normally treated as having closed endpoints.  This
+      applies consistently in the discussion of stacks of extents
+      and such below.  Note that this definition of overlap is not
+      necessarily consistent with the extents that `map-extents'
+      maps over, since `map-extents' sometimes pays attention to
+      whether the endpoints of an extents are open or closed.
+      But for our purposes, it greatly simplifies things to treat
+      all extents as having closed endpoints.
+   
+   First, define >, <, <=, etc. as applied to extents to mean
+     comparison according to the display order.  Comparison between an
+     extent E and an index I means comparison between E and the range
+     [I, I].
+   Also define e>, e<, e<=, etc. to mean comparison according to the
+     e-order.
+   For any range R, define R(0) to be the starting index of the range
+     and R(1) to be the ending index of the range.
+   For any extent E, define E(next) to be the extent directly following
+     E, and E(prev) to be the extent directly preceding E.  Assume
+     E(next) and E(prev) can be determined from E in constant time.
+     (This is because we store the extent list as a doubly linked
+     list.)
+   Similarly, define E(e-next) and E(e-prev) to be the extents
+     directly following and preceding E in the e-order.
+
+   Now:
+
+   Let R be a range.
+   Let F be the first extent overlapping R.
+   Let L be the last extent overlapping R.
+   
+   Theorem 1: R(1) lies between L and L(next), i.e. L <= R(1) < L(next).
+
+   This follows easily from the definition of display order.  The
+   basic reason that this theorem applies is that the display order
+   sorts by increasing starting index.
+
+   Therefore, we can determine L just by looking at where we would
+   insert R(1) into the list, and if we know F and are moving forward
+   over extents, we can easily determine when we've hit L by comparing
+   the extent we're at to R(1).
+
+   Theorem 2: F(e-prev) e< [1, R(0)] e<= F.
+
+   This is the analog of Theorem 1, and applies because the e-order
+   sorts by increasing ending index.
+
+   Therefore, F can be found in the same amount of time as operation (1),
+   i.e. the time that it takes to locate where an extent would go if
+   inserted into the e-order list.
+
+   If the lists were stored as balanced binary trees, then operation (1)
+   would take logarithmic time, which is usually quite fast.  However,
+   currently they're stored as simple doubly-linked lists, and instead
+   we do some caching to try to speed things up.
+
+   Define a "stack of extents" (or "SOE") as the set of extents
+   (ordered in the display order) that overlap an index I, together with
+   the SOE's "previous" extent, which is an extent that precedes I in
+   the e-order. (Hopefully there will not be very many extents between
+   I and the previous extent.)
+
+   Now:
+
+   Let I be an index, let S be the stack of extents on I, let F be
+   the first extent in S, and let P be S's previous extent.
+
+   Theorem 3: The first extent in S is the first extent that overlaps
+   any range [I, J].
+
+   Proof: Any extent that overlaps [I, J] but does not include I must
+   have a start index > I, and thus be greater than any extent in S.
+
+   Therefore, finding the first extent that overlaps a range R is the
+   same as finding the first extent that overlaps R(0).
+
+   Theorem 4: Let I2 be an index such that I2 > I, and let F2 be the
+   first extent that overlaps I2.  Then, either F2 is in S or F2 is
+   greater than any extent in S.
+
+   Proof: If F2 does not include I then its start index is greater
+   than I and thus it is greater than any extent in S, including F.
+   Otherwise, F2 includes I and thus is in S, and thus F2 >= F.
+
+*/
+
+#include <config.h>
+#include "lisp.h"
+
+#include "buffer.h" 
+#include "debug.h"
+#include "device.h"
+#include "elhash.h"
+#include "extents.h"
+#include "faces.h"
+#include "frame.h"
+#include "glyphs.h"
+#include "hash.h"
+#include "insdel.h"
+#include "opaque.h"
+#include "process.h"
+#include "redisplay.h"
+
+/* ------------------------------- */
+/*            gap array            */
+/* ------------------------------- */
+
+/* Note that this object is not extent-specific and should perhaps be
+   moved into another file. */
+
+/* Holds a marker that moves as elements in the array are inserted and
+   deleted, similar to standard markers. */
+
+typedef struct gap_array_marker
+{
+  int pos;
+  struct gap_array_marker *next;
+} Gap_Array_Marker;
+
+/* Holds a "gap array", which is an array of elements with a gap located
+   in it.  Insertions and deletions with a high degree of locality
+   are very fast, essentially in constant time.  Array positions as
+   used and returned in the gap array functions are independent of
+   the gap. */
+
+typedef struct gap_array
+{
+  char *array;
+  int gap;
+  int gapsize;
+  int numels;
+  int elsize;
+  Gap_Array_Marker *markers;
+} Gap_Array;
+
+Gap_Array_Marker *gap_array_marker_freelist;
+
+/* Convert a "memory position" (i.e. taking the gap into account) into
+   the address of the element at (i.e. after) that position.  "Memory
+   positions" are only used internally and are of type Memind.
+   "Array positions" are used externally and are of type int. */
+#define GAP_ARRAY_MEMEL_ADDR(ga, memel) ((ga)->array + (ga)->elsize*(memel))
+
+/* Number of elements currently in a gap array */
+#define GAP_ARRAY_NUM_ELS(ga) ((ga)->numels)
+
+#define GAP_ARRAY_ARRAY_TO_MEMORY_POS(ga, pos) \
+  ((pos) <= (ga)->gap ? (pos) : (pos) + (ga)->gapsize)
+
+#define GAP_ARRAY_MEMORY_TO_ARRAY_POS(ga, pos) \
+  ((pos) <= (ga)->gap ? (pos) : (pos) - (ga)->gapsize)
+
+/* Convert an array position into the address of the element at
+   (i.e. after) that position. */
+#define GAP_ARRAY_EL_ADDR(ga, pos) ((pos) < (ga)->gap ? \
+  GAP_ARRAY_MEMEL_ADDR(ga, pos) : \
+  GAP_ARRAY_MEMEL_ADDR(ga, (pos) + (ga)->gapsize))
+
+/* ------------------------------- */
+/*          extent list            */
+/* ------------------------------- */
+
+typedef struct extent_list_marker
+{
+  Gap_Array_Marker *m;
+  int endp;
+  struct extent_list_marker *next;
+} Extent_List_Marker;
+
+typedef struct extent_list
+{
+  Gap_Array *start;
+  Gap_Array *end;
+  Extent_List_Marker *markers;
+} Extent_List;
+
+Extent_List_Marker *extent_list_marker_freelist;
+
+#define EXTENT_LESS_VALS(e,st,nd) ((extent_start (e) < (st)) || \
+				   ((extent_start (e) == (st)) && \
+				    (extent_end (e) > (nd))))
+
+#define EXTENT_EQUAL_VALS(e,st,nd) ((extent_start (e) == (st)) && \
+				    (extent_end (e) == (nd)))
+
+#define EXTENT_LESS_EQUAL_VALS(e,st,nd) ((extent_start (e) < (st)) || \
+					 ((extent_start (e) == (st)) && \
+					  (extent_end (e) >= (nd))))
+
+/* Is extent E1 less than extent E2 in the display order? */
+#define EXTENT_LESS(e1,e2) \
+  EXTENT_LESS_VALS (e1, extent_start (e2), extent_end (e2))
+
+/* Is extent E1 equal to extent E2? */
+#define EXTENT_EQUAL(e1,e2) \
+  EXTENT_EQUAL_VALS (e1, extent_start (e2), extent_end (e2))
+
+/* Is extent E1 less than or equal to extent E2 in the display order? */
+#define EXTENT_LESS_EQUAL(e1,e2) \
+  EXTENT_LESS_EQUAL_VALS (e1, extent_start (e2), extent_end (e2))
+
+#define EXTENT_E_LESS_VALS(e,st,nd) ((extent_end (e) < (nd)) || \
+				     ((extent_end (e) == (nd)) && \
+				      (extent_start (e) > (st))))
+
+#define EXTENT_E_LESS_EQUAL_VALS(e,st,nd) ((extent_end (e) < (nd)) || \
+					   ((extent_end (e) == (nd)) && \
+					    (extent_start (e) >= (st))))
+
+/* Is extent E1 less than extent E2 in the e-order? */
+#define EXTENT_E_LESS(e1,e2) \
+	EXTENT_E_LESS_VALS(e1, extent_start (e2), extent_end (e2))
+
+/* Is extent E1 less than or equal to extent E2 in the e-order? */
+#define EXTENT_E_LESS_EQUAL(e1,e2) \
+  EXTENT_E_LESS_EQUAL_VALS (e1, extent_start (e2), extent_end (e2))
+
+#define EXTENT_GAP_ARRAY_AT(ga, pos) (* (EXTENT *) GAP_ARRAY_EL_ADDR(ga, pos))
+
+/* ------------------------------- */
+/*    auxiliary extent structure   */
+/* ------------------------------- */
+
+struct extent_auxiliary extent_auxiliary_defaults;
+
+MAC_DEFINE (EXTENT, MTancestor_extent)
+MAC_DEFINE (EXTENT, MTaux_extent)
+MAC_DEFINE (EXTENT, MTplist_extent)
+MAC_DEFINE (EXTENT, MTensure_extent)
+MAC_DEFINE (EXTENT, MTset_extent)
+
+/* ------------------------------- */
+/*     buffer-extent primitives    */
+/* ------------------------------- */
+
+typedef struct stack_of_extents
+{
+  Extent_List *extents;
+  Memind pos; /* Position of stack of extents.  EXTENTS is the list of
+		 all extents that overlap this position.  This position
+		 can be -1 if the stack of extents is invalid (this
+		 happens when a buffer is first created or a string's
+		 stack of extents is created [a string's stack of extents
+		 is nuked when a GC occurs, to conserve memory]). */
+} Stack_Of_Extents;
+
+/* ------------------------------- */
+/*           map-extents           */
+/* ------------------------------- */
+
+typedef int Endpoint_Index;
+
+#define memind_to_startind(x, start_open) \
+  ((Endpoint_Index) (((x) << 1) + !!(start_open)))
+#define memind_to_endind(x, end_open) \
+  ((Endpoint_Index) (((x) << 1) - !!(end_open)))
+
+/* Combination macros */
+#define bytind_to_startind(buf, x, start_open) \
+  memind_to_startind (bytind_to_memind (buf, x), start_open)
+#define bytind_to_endind(buf, x, end_open) \
+  memind_to_endind (bytind_to_memind (buf, x), end_open)
+
+/* ------------------------------- */
+/*    buffer-or-string primitives  */
+/* ------------------------------- */
+
+/* Similar for Bytinds and start/end indices. */
+
+#define buffer_or_string_bytind_to_startind(obj, ind, start_open)	\
+  memind_to_startind (buffer_or_string_bytind_to_memind (obj, ind),	\
+		      start_open)
+
+#define buffer_or_string_bytind_to_endind(obj, ind, end_open)		\
+  memind_to_endind (buffer_or_string_bytind_to_memind (obj, ind),	\
+		    end_open)
+
+/* ------------------------------- */
+/*      Lisp-level functions       */
+/* ------------------------------- */
+
+/* flags for decode_extent() */
+#define DE_MUST_HAVE_BUFFER 1
+#define DE_MUST_BE_ATTACHED 2
+
+/* #### remove this crap */
+#ifdef ENERGIZE
+extern void restore_energize_extent_state (EXTENT extent);
+#endif
+
+Lisp_Object Vlast_highlighted_extent;
+int mouse_highlight_priority;
+
+Lisp_Object Qextentp;
+Lisp_Object Qextent_live_p;
+
+Lisp_Object Qend_closed;
+Lisp_Object Qstart_open;
+Lisp_Object Qall_extents_closed;
+Lisp_Object Qall_extents_open;
+Lisp_Object Qall_extents_closed_open;
+Lisp_Object Qall_extents_open_closed;
+Lisp_Object Qstart_in_region;
+Lisp_Object Qend_in_region;
+Lisp_Object Qstart_and_end_in_region;
+Lisp_Object Qstart_or_end_in_region;
+Lisp_Object Qnegate_in_region;
+
+Lisp_Object Qdetached;
+Lisp_Object Qdestroyed;
+Lisp_Object Qbegin_glyph;
+Lisp_Object Qend_glyph;
+Lisp_Object Qstart_open;
+Lisp_Object Qend_open;
+Lisp_Object Qstart_closed;
+Lisp_Object Qend_closed;
+Lisp_Object Qread_only;
+/* Qhighlight defined in general.c */
+Lisp_Object Qunique;
+Lisp_Object Qduplicable;
+Lisp_Object Qreplicating;
+Lisp_Object Qdetachable;
+Lisp_Object Qpriority;
+Lisp_Object Qmouse_face;
+
+Lisp_Object Qglyph_layout;  /* This exists only for backwards compatibility. */
+Lisp_Object Qbegin_glyph_layout, Qend_glyph_layout;
+Lisp_Object Qoutside_margin;
+Lisp_Object Qinside_margin;
+Lisp_Object Qwhitespace;
+/* Qtext defined in general.c */
+
+/* partially used in redisplay */
+Lisp_Object Qglyph_invisible;
+
+Lisp_Object Qcopy_function;
+Lisp_Object Qpaste_function;
+
+/* The idea here is that if we're given a list of faces, we
+   need to "memoize" this so that two lists of faces that are `equal'
+   turn into the same object.  When `set-extent-face' is called, we
+   "memoize" into a list of actual faces; when `extent-face' is called,
+   we do a reverse lookup to get the list of symbols. */
+
+static Lisp_Object canonicalize_extent_property (Lisp_Object prop,
+						 Lisp_Object value);
+Lisp_Object Vextent_face_memoize_hash_table;
+Lisp_Object Vextent_face_reverse_memoize_hash_table;
+Lisp_Object Vextent_face_reusable_list;
+/* FSFmacs bogosity */
+Lisp_Object Vdefault_text_properties;
+
+
+/************************************************************************/
+/*                       Generalized gap array                          */
+/************************************************************************/
+
+/* This generalizes the "array with a gap" model used to store buffer
+   characters.  This is based on the stuff in insdel.c and should
+   probably be merged with it.  This is not extent-specific and should
+   perhaps be moved into a separate file. */
+
+/* ------------------------------- */
+/*        internal functions       */
+/* ------------------------------- */
+
+/* Adjust the gap array markers in the range (FROM, TO].  Parallel to
+   adjust_markers() in insdel.c. */
+
+static void
+gap_array_adjust_markers (Gap_Array *ga, Memind from,
+			  Memind to, int amount)
+{
+  Gap_Array_Marker *m;
+
+  for (m = ga->markers; m; m = m->next)
+    m->pos = do_marker_adjustment (m->pos, from, to, amount);
+}
+
+/* Move the gap to array position POS.  Parallel to move_gap() in
+   insdel.c but somewhat simplified. */
+
+static void
+gap_array_move_gap (Gap_Array *ga, int pos)
+{
+  int gap = ga->gap;
+  int gapsize = ga->gapsize;
+
+  assert (ga->array);
+  if (pos < gap)
+    {
+      memmove (GAP_ARRAY_MEMEL_ADDR (ga, pos + gapsize),
+	       GAP_ARRAY_MEMEL_ADDR (ga, pos),
+	       (gap - pos)*ga->elsize);
+      gap_array_adjust_markers (ga, (Memind) pos, (Memind) gap,
+				gapsize);
+    }
+  else if (pos > gap)
+    {
+      memmove (GAP_ARRAY_MEMEL_ADDR (ga, gap),
+	       GAP_ARRAY_MEMEL_ADDR (ga, gap + gapsize),
+	       (pos - gap)*ga->elsize);
+      gap_array_adjust_markers (ga, (Memind) (gap + gapsize),
+				(Memind) (pos + gapsize), - gapsize);
+    }
+  ga->gap = pos;
+}
+
+/* Make the gap INCREMENT characters longer.  Parallel to make_gap() in
+   insdel.c. */
+
+static void
+gap_array_make_gap (Gap_Array *ga, int increment)
+{
+  char *ptr = ga->array;
+  int real_gap_loc;
+  int old_gap_size;
+
+  /* If we have to get more space, get enough to last a while.  We use
+     a geometric progession that saves on realloc space. */
+  increment += 100 + ga->numels / 8;
+
+  ptr = xrealloc (ptr,
+		  (ga->numels + ga->gapsize + increment)*ga->elsize);
+  if (ptr == 0)
+    memory_full ();
+  ga->array = ptr;
+
+  real_gap_loc = ga->gap;
+  old_gap_size = ga->gapsize;
+
+  /* Call the newly allocated space a gap at the end of the whole space.  */
+  ga->gap = ga->numels + ga->gapsize;
+  ga->gapsize = increment;
+
+  /* Move the new gap down to be consecutive with the end of the old one.
+     This adjusts the markers properly too.  */
+  gap_array_move_gap (ga, real_gap_loc + old_gap_size);
+
+  /* Now combine the two into one large gap.  */
+  ga->gapsize += old_gap_size;
+  ga->gap = real_gap_loc;
+}
+
+/* ------------------------------- */
+/*        external functions       */
+/* ------------------------------- */
+
+/* Insert NUMELS elements (pointed to by ELPTR) into the specified
+   gap array at POS. */
+
+static void
+gap_array_insert_els (Gap_Array *ga, int pos, void *elptr, int numels)
+{
+  assert (pos >= 0 && pos <= ga->numels);
+  if (ga->gapsize < numels)
+    gap_array_make_gap (ga, numels - ga->gapsize);
+  if (pos != ga->gap)
+    gap_array_move_gap (ga, pos);
+
+  memcpy (GAP_ARRAY_MEMEL_ADDR (ga, ga->gap), (char *) elptr,
+	  numels*ga->elsize);
+  ga->gapsize -= numels;
+  ga->gap += numels;
+  ga->numels += numels;
+  /* This is the equivalent of insert-before-markers.
+
+     #### Should only happen if marker is "moves forward at insert" type.
+     */
+
+  gap_array_adjust_markers (ga, pos - 1, pos, numels);
+}
+
+/* Delete NUMELS elements from the specified gap array, starting at FROM. */
+
+static void
+gap_array_delete_els (Gap_Array *ga, int from, int numdel)
+{
+  int to = from + numdel;
+  int gapsize = ga->gapsize;
+
+  assert (from >= 0);
+  assert (numdel >= 0);
+  assert (to <= ga->numels);
+
+  /* Make sure the gap is somewhere in or next to what we are deleting.  */
+  if (to < ga->gap)
+    gap_array_move_gap (ga, to);
+  if (from > ga->gap)
+    gap_array_move_gap (ga, from);
+
+  /* Relocate all markers pointing into the new, larger gap
+     to point at the end of the text before the gap.  */
+  gap_array_adjust_markers (ga, to + gapsize, to + gapsize,
+			    - numdel - gapsize);
+
+  ga->gapsize += numdel;
+  ga->numels -= numdel;
+  ga->gap = from;
+}
+
+static Gap_Array_Marker *
+gap_array_make_marker (Gap_Array *ga, int pos)
+{
+  Gap_Array_Marker *m;
+
+  assert (pos >= 0 && pos <= ga->numels);
+  if (gap_array_marker_freelist)
+    {
+      m = gap_array_marker_freelist;
+      gap_array_marker_freelist = gap_array_marker_freelist->next;
+    }
+  else
+    m = (Gap_Array_Marker *) xmalloc (sizeof (*m));
+
+  m->pos = GAP_ARRAY_ARRAY_TO_MEMORY_POS (ga, pos);
+  m->next = ga->markers;
+  ga->markers = m;
+  return m;
+}
+
+static void
+gap_array_delete_marker (Gap_Array *ga, Gap_Array_Marker *m)
+{
+  Gap_Array_Marker *p, *prev;
+
+  for (prev = 0, p = ga->markers; p && p != m; prev = p, p = p->next)
+    ;
+  assert (p);
+  if (prev)
+    prev->next = p->next;
+  else
+    ga->markers = p->next;
+  m->next = gap_array_marker_freelist;
+  m->pos = 0xDEADBEEF; /* -559038737 as an int */
+  gap_array_marker_freelist = m;
+}
+
+static void
+gap_array_delete_all_markers (Gap_Array *ga)
+{
+  Gap_Array_Marker *p, *next;
+
+  for (p = ga->markers; p; p = next)
+    {
+      next = p->next;
+      p->next = gap_array_marker_freelist;
+      p->pos = 0xDEADBEEF; /* -559038737 as an int */
+      gap_array_marker_freelist = p;
+    }
+}
+
+static void
+gap_array_move_marker (Gap_Array *ga, Gap_Array_Marker *m, int pos)
+{
+  assert (pos >= 0 && pos <= ga->numels);
+  m->pos = GAP_ARRAY_ARRAY_TO_MEMORY_POS (ga, pos);
+}
+
+#define gap_array_marker_pos(ga, m) \
+  GAP_ARRAY_MEMORY_TO_ARRAY_POS (ga, (m)->pos)
+
+static Gap_Array *
+make_gap_array (int elsize)
+{
+  Gap_Array *ga = (Gap_Array *) xmalloc (sizeof(*ga));
+  memset (ga, 0, sizeof(*ga));
+  ga->elsize = elsize;
+  return ga;
+}
+
+static void
+free_gap_array (Gap_Array *ga)
+{
+  if (ga->array)
+    xfree (ga->array);
+  gap_array_delete_all_markers (ga);
+  xfree (ga);
+}
+
+
+/************************************************************************/
+/*                       Extent list primitives                         */
+/************************************************************************/
+
+/* A list of extents is maintained as a double gap array: one gap array
+   is ordered by start index (the "display order") and the other is
+   ordered by end index (the "e-order").  Note that positions in an
+   extent list should logically be conceived of as referring *to*
+   a particular extent (as is the norm in programs) rather than
+   sitting between two extents.  Note also that callers of these
+   functions should not be aware of the fact that the extent list is
+   implemented as an array, except for the fact that positions are
+   integers (this should be generalized to handle integers and linked
+   list equally well).
+*/
+
+/* Number of elements in an extent list */
+#define extent_list_num_els(el) GAP_ARRAY_NUM_ELS(el->start)
+
+/* Return the position at which EXTENT is located in the specified extent
+   list (in the display order if ENDP is 0, in the e-order otherwise).
+   If the extent is not found, the position where the extent would
+   be inserted is returned.  If ENDP is 0, the insertion would go after
+   all other equal extents.  If ENDP is not 0, the insertion would go
+   before all other equal extents.  If FOUNDP is not 0, then whether
+   the extent was found will get written into it. */
+
+static int
+extent_list_locate (Extent_List *el, EXTENT extent, int endp, int *foundp)
+{
+  Gap_Array *ga = endp ? el->end : el->start;
+  int left = 0, right = GAP_ARRAY_NUM_ELS (ga);
+  int oldfoundpos, foundpos;
+  int found;
+  EXTENT e;
+
+  while (left != right)
+    {
+      /* RIGHT might not point to a valid extent (i.e. it's at the end
+	 of the list), so NEWPOS must round down. */
+      unsigned int newpos = (left + right) >> 1;
+      e = EXTENT_GAP_ARRAY_AT (ga, newpos);
+      
+      if (endp ? EXTENT_E_LESS (e, extent) : EXTENT_LESS (e, extent))
+	left = newpos+1;
+      else
+	right = newpos;
+    }
+
+  /* Now we're at the beginning of all equal extents. */
+  found = 0;
+  oldfoundpos = foundpos = left;
+  while (foundpos < GAP_ARRAY_NUM_ELS (ga))
+    {
+      e = EXTENT_GAP_ARRAY_AT (ga, foundpos);
+      if (e == extent)
+	{
+	  found = 1;
+	  break;
+	}
+      if (!EXTENT_EQUAL (e, extent))
+	break;
+      foundpos++;
+    }
+  if (foundp)
+    *foundp = found;
+  if (found || !endp)
+    return foundpos;
+  else
+    return oldfoundpos;
+}
+
+/* Return the position of the first extent that begins at or after POS
+   (or ends at or after POS, if ENDP is not 0).
+
+   An out-of-range value for POS is allowed, and guarantees that the
+   position at the beginning or end of the extent list is returned. */
+
+static int
+extent_list_locate_from_pos (Extent_List *el, Memind pos, int endp)
+{
+  struct extent fake_extent;
+  /*
+
+   Note that if we search for [POS, POS], then we get the following:
+
+   -- if ENDP is 0, then all extents whose start position is <= POS
+      lie before the returned position, and all extents whose start
+      position is > POS lie at or after the returned position.
+
+   -- if ENDP is not 0, then all extents whose end position is < POS
+      lie before the returned position, and all extents whose end
+      position is >= POS lie at or after the returned position.
+
+   */
+  set_extent_start (&fake_extent, endp ? pos : pos-1);
+  set_extent_end (&fake_extent, endp ? pos : pos-1);
+  return extent_list_locate (el, &fake_extent, endp, 0);
+}
+
+/* Return the extent at POS. */
+
+static EXTENT
+extent_list_at (Extent_List *el, Memind pos, int endp)
+{
+  Gap_Array *ga = endp ? el->end : el->start;
+
+  assert (pos >= 0 && pos < GAP_ARRAY_NUM_ELS (ga));
+  return EXTENT_GAP_ARRAY_AT (ga, pos);
+}
+
+/* Insert an extent into an extent list. */
+
+static void
+extent_list_insert (Extent_List *el, EXTENT extent)
+{
+  int pos, foundp;
+
+  pos = extent_list_locate (el, extent, 0, &foundp);
+  assert (!foundp);
+  gap_array_insert_els (el->start, pos, &extent, 1);
+  pos = extent_list_locate (el, extent, 1, &foundp);
+  assert (!foundp);
+  gap_array_insert_els (el->end, pos, &extent, 1);
+}
+
+/* Delete an extent from an extent list. */
+
+static void
+extent_list_delete (Extent_List *el, EXTENT extent)
+{
+  int pos, foundp;
+
+  pos = extent_list_locate (el, extent, 0, &foundp);
+  assert (foundp);
+  gap_array_delete_els (el->start, pos, 1);
+  pos = extent_list_locate (el, extent, 1, &foundp);
+  assert (foundp);
+  gap_array_delete_els (el->end, pos, 1);
+}
+
+static void
+extent_list_delete_all (Extent_List *el)
+{
+  gap_array_delete_els (el->start, 0, GAP_ARRAY_NUM_ELS (el->start));
+  gap_array_delete_els (el->end, 0, GAP_ARRAY_NUM_ELS (el->end));
+}
+
+static Extent_List_Marker *
+extent_list_make_marker (Extent_List *el, int pos, int endp)
+{
+  Extent_List_Marker *m;
+
+  if (extent_list_marker_freelist)
+    {
+      m = extent_list_marker_freelist;
+      extent_list_marker_freelist = extent_list_marker_freelist->next;
+    }
+  else
+    m = (Extent_List_Marker *) xmalloc (sizeof (*m));
+
+  m->m = gap_array_make_marker (endp ? el->end : el->start, pos);
+  m->endp = endp;
+  m->next = el->markers;
+  el->markers = m;
+  return m;
+}
+
+#define extent_list_move_marker(el, mkr, pos) \
+  gap_array_move_marker((mkr)->endp ? (el)->end : (el)->start, (mkr)->m, pos)
+
+static void
+extent_list_delete_marker (Extent_List *el, Extent_List_Marker *m)
+{
+  Extent_List_Marker *p, *prev;
+
+  for (prev = 0, p = el->markers; p && p != m; prev = p, p = p->next)
+    ;
+  assert (p);
+  if (prev)
+    prev->next = p->next;
+  else
+    el->markers = p->next;
+  m->next = extent_list_marker_freelist;
+  extent_list_marker_freelist = m;
+  gap_array_delete_marker (m->endp ? el->end : el->start, m->m);
+}
+
+#define extent_list_marker_pos(el, mkr) \
+  gap_array_marker_pos ((mkr)->endp ? (el)->end : (el)->start, (mkr)->m)
+
+static Extent_List *
+allocate_extent_list (void)
+{
+  Extent_List *el = (Extent_List *) xmalloc (sizeof(*el));
+  el->start = make_gap_array (sizeof(EXTENT));
+  el->end = make_gap_array (sizeof(EXTENT));
+  el->markers = 0;
+  return el;
+}
+
+static void
+free_extent_list (Extent_List *el)
+{
+  free_gap_array (el->start);
+  free_gap_array (el->end);
+  xfree (el);
+}
+
+
+/************************************************************************/
+/*                       Auxiliary extent structure                     */
+/************************************************************************/
+
+static Lisp_Object mark_extent_auxiliary (Lisp_Object obj,
+					  void (*markobj) (Lisp_Object));
+DEFINE_LRECORD_IMPLEMENTATION ("extent-auxiliary", extent_auxiliary,
+                               mark_extent_auxiliary, internal_object_printer,
+			       0, 0, 0, struct extent_auxiliary);
+
+static Lisp_Object
+mark_extent_auxiliary (Lisp_Object obj, void (*markobj) (Lisp_Object))
+{
+  struct extent_auxiliary *data =
+    (struct extent_auxiliary *) XEXTENT_AUXILIARY (obj);
+  ((markobj) (data->begin_glyph));
+  ((markobj) (data->end_glyph));
+  ((markobj) (data->invisible));
+  ((markobj) (data->children));
+  ((markobj) (data->read_only));
+  ((markobj) (data->mouse_face));
+  return (data->parent);
+}
+
+void
+allocate_extent_auxiliary (EXTENT ext)
+{
+  Lisp_Object extent_aux = Qnil;
+  struct extent_auxiliary *data =
+    alloc_lcrecord (sizeof (struct extent_auxiliary),
+		    lrecord_extent_auxiliary);
+
+  copy_lcrecord (data, &extent_auxiliary_defaults);
+  XSETEXTENT_AUXILIARY (extent_aux, data);
+  ext->plist = Fcons (extent_aux, ext->plist);
+  ext->flags.has_aux = 1;
+}
+
+
+/************************************************************************/
+/*                         Extent info structure                        */
+/************************************************************************/
+
+/* An extent-info structure consists of a list of the buffer or string's
+   extents and a "stack of extents" that lists all of the extents over
+   a particular position.  The stack-of-extents info is used for
+   optimization purposes -- it basically caches some info that might
+   be expensive to compute.  Certain otherwise hard computations are easy
+   given the stack of extents over a particular position, and if the
+   stack of extents over a nearby position is known (because it was
+   calculated at some prior point in time), it's easy to move the stack
+   of extents to the proper position.
+
+   Given that the stack of extents is an optimization, and given that
+   it requires memory, a string's stack of extents is wiped out each
+   time a garbage collection occurs.  Therefore, any time you retrieve
+   the stack of extents, it might not be there.  If you need it to
+   be there, use the _force version.
+
+   Similarly, a string may or may not have an extent_info struture.
+   (Generally it won't if there haven't been any extents added to the
+   string.) So use the _force version if you need the extent_info
+   structure to be there. */
+
+static struct stack_of_extents *allocate_soe (void);
+static void free_soe (struct stack_of_extents *soe);
+static void soe_invalidate (Lisp_Object obj);
+
+static Lisp_Object mark_extent_info (Lisp_Object obj,
+				     void (*markobj) (Lisp_Object));
+static void finalize_extent_info (void *header, int for_disksave);
+DEFINE_LRECORD_IMPLEMENTATION ("extent-info", extent_info,
+                               mark_extent_info, internal_object_printer,
+			       finalize_extent_info, 0, 0,
+			       struct extent_info);
+
+static Lisp_Object
+mark_extent_info (Lisp_Object obj, void (*markobj) (Lisp_Object))
+{
+  struct extent_info *data =
+    (struct extent_info *) XEXTENT_INFO (obj);
+  int i;
+  Extent_List *list;
+
+  /* Vbuffer_defaults and Vbuffer_local_symbols are buffer-like
+     objects that are created specially and never have their extent
+     list initialized (or rather, it is set to zero in
+     nuke_all_buffer_slots()).  However, these objects get
+     garbage-collected so we have to deal.
+
+     (Also the list can be zero when we're dealing with a destroyed
+     buffer.) */
+
+  list = data->extents;
+  if (list)
+    {
+      for (i = 0; i < extent_list_num_els (list); i++)
+	{
+	  struct extent *extent = extent_list_at (list, i, 0);
+	  Lisp_Object exobj = Qnil;
+
+	  XSETEXTENT (exobj, extent);
+	  ((markobj) (exobj));
+	}
+    }
+
+  return Qnil;
+}
+
+static void
+finalize_extent_info (void *header, int for_disksave)
+{
+  struct extent_info *data = (struct extent_info *) header;
+
+  if (for_disksave)
+    return;
+
+  if (data->soe)
+    {
+      free_soe (data->soe);
+      data->soe = 0;
+    }
+  if (data->extents)
+    {
+      free_extent_list (data->extents);
+      data->extents = 0;
+    }
+}
+
+static Lisp_Object
+allocate_extent_info (void)
+{
+  Lisp_Object extent_info = Qnil;
+  struct extent_info *data =
+    alloc_lcrecord (sizeof (struct extent_info),
+		    lrecord_extent_info);
+
+  XSETEXTENT_INFO (extent_info, data);
+  data->extents = allocate_extent_list ();
+  data->soe = 0;
+  return extent_info;
+}
+
+void
+flush_cached_extent_info (Lisp_Object extent_info)
+{
+  struct extent_info *data = XEXTENT_INFO (extent_info);
+
+  if (data->soe)
+    {
+      free_soe (data->soe);
+      data->soe = 0;
+    }
+}
+
+
+/************************************************************************/
+/*                    Buffer/string extent primitives                   */
+/************************************************************************/
+
+/* The functions in this section are the ONLY ones that should know
+   about the internal implementation of the extent lists.  Other functions
+   should only know that there are two orderings on extents, the "display"
+   order (sorted by start position, basically) and the e-order (sorted
+   by end position, basically), and that certain operations are provided
+   to manipulate the list. */
+
+/* ------------------------------- */
+/*        basic primitives         */
+/* ------------------------------- */
+
+static Lisp_Object
+decode_buffer_or_string (Lisp_Object object)
+{
+  if (NILP (object))
+    XSETBUFFER (object, current_buffer);
+  else
+    CHECK_LIVE_BUFFER_OR_STRING (object);
+  return object;
+}  
+
+EXTENT
+extent_ancestor_1 (EXTENT e)
+{
+  while (e->flags.has_parent)
+    {
+      /* There should be no circularities except in case of a logic
+	 error somewhere in the extent code */
+      e = XEXTENT (XEXTENT_AUXILIARY (XCAR (e->plist))->parent);
+    }
+  return e;
+}
+
+/* Given an extent object (string or buffer or nil), return its extent info.  This may be
+   0 for a string. */
+
+static struct extent_info *
+buffer_or_string_extent_info (Lisp_Object object)
+{
+  if (STRINGP (object))
+    {
+      Lisp_Object plist = XSTRING (object)->plist;
+      if (!CONSP (plist) || !EXTENT_INFOP (XCAR (plist)))
+	return 0;
+      return XEXTENT_INFO (XCAR (plist));
+    }
+  else if (NILP (object))
+    return 0;
+  else
+    return XEXTENT_INFO (XBUFFER (object)->extent_info);
+}
+
+/* Given a string or buffer, return its extent list.  This may be
+   0 for a string. */
+
+static Extent_List *
+buffer_or_string_extent_list (Lisp_Object object)
+{
+  struct extent_info *info = buffer_or_string_extent_info (object);
+
+  if (!info)
+    return 0;
+  return info->extents;
+}
+
+/* Given a string or buffer, return its extent info.  If it's not there,
+   create it. */
+
+static struct extent_info *
+buffer_or_string_extent_info_force (Lisp_Object object)
+{
+  struct extent_info *info = buffer_or_string_extent_info (object);
+  
+  if (!info)
+    {
+      Lisp_Object extent_info;
+
+      assert (STRINGP (object)); /* should never happen for buffers --
+				    the only buffers without an extent
+				    info are those after finalization,
+				    destroyed buffers, or special
+				    Lisp-inaccessible buffer objects. */
+      extent_info = allocate_extent_info ();
+      XSTRING (object)->plist = Fcons (extent_info, XSTRING (object)->plist);
+      return XEXTENT_INFO (extent_info);
+    }
+
+  return info;
+}
+
+/* Detach all the extents in OBJECT.  Called from redisplay. */
+
+void
+detach_all_extents (Lisp_Object object)
+{
+  struct extent_info *data = buffer_or_string_extent_info (object);
+
+  if (data)
+    {
+      if (data->extents)
+	{
+	  int i;
+
+	  for (i = 0; i < extent_list_num_els (data->extents); i++)
+	    {
+	      EXTENT e = extent_list_at (data->extents, i, 0);
+	      /* No need to do detach_extent().  Just nuke the damn things,
+		 which results in the equivalent but faster. */
+	      set_extent_start (e, -1);
+	      set_extent_end (e, -1);
+	    }
+	}
+
+      /* But we need to clear all the lists containing extents or
+	 havoc will result. */
+      extent_list_delete_all (data->extents);
+      soe_invalidate (object);
+    }
+}
+
+
+void
+init_buffer_extents (struct buffer *b)
+{
+  b->extent_info = allocate_extent_info ();
+}
+
+void
+uninit_buffer_extents (struct buffer *b)
+{
+  struct extent_info *data = XEXTENT_INFO (b->extent_info);
+
+  /* Don't destroy the extents here -- there may still be children
+     extents pointing to the extents. */
+  detach_all_extents (make_buffer (b));
+  finalize_extent_info (data, 0);
+}
+
+/* Retrieve the extent list that an extent is a member of; the
+   return value will never be 0 except in destroyed buffers (in which
+   case the only extents that can refer to this buffer are detached
+   ones). */
+
+#define extent_extent_list(e) buffer_or_string_extent_list (extent_object (e))
+
+/* ------------------------------- */
+/*        stack of extents         */
+/* ------------------------------- */
+
+#ifdef ERROR_CHECK_EXTENTS
+
+void
+sledgehammer_extent_check (Lisp_Object object)
+{
+  int i;
+  int endp;
+  Extent_List *el = buffer_or_string_extent_list (object);
+  struct buffer *buf = 0;
+
+  if (!el)
+    return;
+
+  if (BUFFERP (object))
+    buf = XBUFFER (object);
+
+  for (endp = 0; endp < 2; endp++)
+    for (i = 1; i < extent_list_num_els (el); i++)
+      {
+        EXTENT e1 = extent_list_at (el, i-1, endp);
+	EXTENT e2 = extent_list_at (el, i, endp);
+	if (buf)
+	  {
+	    assert (extent_start (e1) <= buf->text->gpt ||
+		    extent_start (e1) > buf->text->gpt + buf->text->gap_size);
+	    assert (extent_end (e1) <= buf->text->gpt ||
+		    extent_end (e1) > buf->text->gpt + buf->text->gap_size);
+	  }
+	assert (extent_start (e1) <= extent_end (e1));
+	assert (endp ? (EXTENT_E_LESS_EQUAL (e1, e2)) :
+		       (EXTENT_LESS_EQUAL (e1, e2)));
+      }
+}
+
+#endif
+
+static Stack_Of_Extents *
+buffer_or_string_stack_of_extents (Lisp_Object object)
+{
+  struct extent_info *info = buffer_or_string_extent_info (object);
+  if (!info)
+    return 0;
+  return info->soe;
+}
+
+static Stack_Of_Extents *
+buffer_or_string_stack_of_extents_force (Lisp_Object object)
+{
+  struct extent_info *info = buffer_or_string_extent_info_force (object);
+  if (!info->soe)
+    info->soe = allocate_soe ();
+  return info->soe;
+}
+
+/* #define SOE_DEBUG */
+
+#ifdef SOE_DEBUG
+
+static char *print_extent_1 (char *buf, Lisp_Object extent);
+
+static void
+print_extent_2 (EXTENT e)
+{
+  Lisp_Object extent;
+  char buf[200];
+
+  XSETEXTENT (extent, e);
+  print_extent_1 (buf, extent);
+  printf ("%s", buf);
+}
+
+static void
+soe_dump (Lisp_Object obj)
+{
+  int i;
+  Stack_Of_Extents *soe = buffer_or_string_stack_of_extents (obj);
+  Extent_List *sel;
+  int endp;
+
+  if (!soe)
+    {
+      printf ("No SOE");
+      return;
+    }
+  sel = soe->extents;
+  printf ("SOE pos is %d (memind %d)\n",
+	  soe->pos < 0 ? soe->pos :
+	  buffer_or_string_memind_to_bytind (obj, soe->pos),
+	  soe->pos);
+  for (endp = 0; endp < 2; endp++)
+    {
+      printf (endp ? "SOE end:" : "SOE start:");
+      for (i = 0; i < extent_list_num_els (sel); i++)
+	{
+	  EXTENT e = extent_list_at (sel, i, endp);
+	  printf ("\t");
+	  print_extent_2 (e);
+	}
+      printf ("\n");
+    }
+  printf ("\n");
+}
+
+#endif
+
+/* Insert EXTENT into OBJ's stack of extents, if necessary. */
+
+static void
+soe_insert (Lisp_Object obj, EXTENT extent)
+{
+  Stack_Of_Extents *soe = buffer_or_string_stack_of_extents (obj);
+
+#ifdef SOE_DEBUG
+  printf ("Inserting into SOE: ");
+  print_extent_2 (extent);
+  printf ("\n");
+#endif
+  if (!soe || soe->pos < extent_start (extent) ||
+      soe->pos > extent_end (extent))
+    {
+#ifdef SOE_DEBUG
+      printf ("(not needed)\n\n");
+#endif
+      return;
+    }
+  extent_list_insert (soe->extents, extent);
+#ifdef SOE_DEBUG
+  printf ("SOE afterwards is:\n");
+  soe_dump (obj);
+#endif
+}
+
+/* Delete EXTENT from OBJ's stack of extents, if necessary. */
+
+static void
+soe_delete (Lisp_Object obj, EXTENT extent)
+{
+  Stack_Of_Extents *soe = buffer_or_string_stack_of_extents (obj);
+
+#ifdef SOE_DEBUG
+  printf ("Deleting from SOE: ");
+  print_extent_2 (extent);
+  printf ("\n");
+#endif
+  if (!soe || soe->pos < extent_start (extent) ||
+      soe->pos > extent_end (extent))
+    {
+#ifdef SOE_DEBUG
+      printf ("(not needed)\n\n");
+#endif
+      return;
+    }
+  extent_list_delete (soe->extents, extent);
+#ifdef SOE_DEBUG
+  printf ("SOE afterwards is:\n");
+  soe_dump (obj);
+#endif
+}
+
+/* Move OBJ's stack of extents to lie over the specified position. */
+
+static void
+soe_move (Lisp_Object obj, Memind pos)
+{
+  Stack_Of_Extents *soe = buffer_or_string_stack_of_extents_force (obj);
+  Extent_List *sel = soe->extents;
+  int numsoe = extent_list_num_els (sel);
+  Extent_List *bel = buffer_or_string_extent_list (obj);
+  int direction;
+  int endp;
+
+#ifdef ERROR_CHECK_EXTENTS
+  assert (bel);
+#endif
+
+#ifdef SOE_DEBUG
+  printf ("Moving SOE from %d (memind %d) to %d (memind %d)\n",
+	  soe->pos < 0 ? soe->pos :
+	  buffer_or_string_memind_to_bytind (obj, soe->pos), soe->pos,
+	  buffer_or_string_memind_to_bytind (obj, pos), pos);
+#endif
+  if (soe->pos < pos)
+    {
+      direction = 1;
+      endp = 0;
+    }
+  else if (soe->pos > pos)
+    {
+      direction = -1;
+      endp = 1;
+    }
+  else
+    {
+#ifdef SOE_DEBUG
+      printf ("(not needed)\n\n");
+#endif
+      return;
+    }
+
+  /* For DIRECTION = 1: Any extent that overlaps POS is either in the
+     SOE (if the extent starts at or before SOE->POS) or is greater
+     (in the display order) than any extent in the SOE (if it starts
+     after SOE->POS).
+
+     For DIRECTION = -1: Any extent that overlaps POS is either in the
+     SOE (if the extent ends at or after SOE->POS) or is less (in the
+     e-order) than any extent in the SOE (if it ends before SOE->POS).
+
+     We proceed in two stages:
+
+     1) delete all extents in the SOE that don't overlap POS.
+     2) insert all extents into the SOE that start (or end, when
+        DIRECTION = -1) in (SOE->POS, POS] and that overlap
+	POS. (Don't include SOE->POS in the range because those
+	extents would already be in the SOE.)
+   */
+
+  /* STAGE 1. */
+
+  if (numsoe > 0)
+    {
+      /* Delete all extents in the SOE that don't overlap POS.
+	 This is all extents that end before (or start after,
+	 if DIRECTION = -1) POS.
+       */
+
+      /* Deleting extents from the SOE is tricky because it changes
+	 the positions of extents.  If we are deleting in the forward
+	 direction we have to call extent_list_at() on the same position
+	 over and over again because positions after the deleted element
+	 get shifted back by 1.  To make life simplest, we delete forward
+	 irrespective of DIRECTION.
+       */
+      int start, end;
+      int i;
+
+      if (direction > 0)
+	{
+	  start = 0;
+	  end = extent_list_locate_from_pos (sel, pos, 1);
+	}
+      else
+	{
+	  start = extent_list_locate_from_pos (sel, pos+1, 0);
+	  end = numsoe;
+	}
+
+      for (i = start; i < end; i++)
+	extent_list_delete (sel, extent_list_at (sel, start /* see above */,
+						 !endp));
+    }
+
+  /* STAGE 2. */
+
+  {
+    int start_pos;
+
+    if (direction < 0)
+      start_pos = extent_list_locate_from_pos (bel, soe->pos, endp) - 1;
+    else
+      start_pos = extent_list_locate_from_pos (bel, soe->pos + 1, endp);
+
+    for (; start_pos >= 0 && start_pos < extent_list_num_els (bel);
+	 start_pos += direction)
+      {
+	EXTENT e = extent_list_at (bel, start_pos, endp);
+	if ((direction > 0) ?
+	    (extent_start (e) > pos) :
+	    (extent_end (e) < pos))
+	  break; /* All further extents lie on the far side of POS
+		    and thus can't overlap. */
+	if ((direction > 0) ?
+	    (extent_end (e) >= pos) :
+	    (extent_start (e) <= pos))
+	  extent_list_insert (sel, e);
+      }
+  }
+
+  soe->pos = pos;
+#ifdef SOE_DEBUG
+  printf ("SOE afterwards is:\n");
+  soe_dump (obj);
+#endif
+}
+
+static void
+soe_invalidate (Lisp_Object obj)
+{
+  Stack_Of_Extents *soe = buffer_or_string_stack_of_extents (obj);
+
+  if (soe)
+    {
+      extent_list_delete_all (soe->extents);
+      soe->pos = -1;
+    }
+}
+
+static struct stack_of_extents *
+allocate_soe (void)
+{
+  struct stack_of_extents *soe =
+    malloc_type_and_zero (struct stack_of_extents);
+  soe->extents = allocate_extent_list ();
+  soe->pos = -1;
+  return soe;
+}
+
+static void
+free_soe (struct stack_of_extents *soe)
+{
+  free_extent_list (soe->extents);
+  xfree (soe);
+}
+
+/* ------------------------------- */
+/*        other primitives         */
+/* ------------------------------- */
+
+/* Return the start (endp == 0) or end (endp == 1) of an extent as
+   a byte index.  If you want the value as a memory index, use
+   extent_endpoint().  If you want the value as a buffer position,
+   use extent_endpoint_bufpos(). */
+
+static Bytind 
+extent_endpoint_bytind (EXTENT extent, int endp)
+{
+  assert (EXTENT_LIVE_P (extent));
+  assert (!extent_detached_p (extent));
+  {
+    Memind i = (endp) ? (extent_end (extent)) :
+      (extent_start (extent));
+    Lisp_Object obj = extent_object (extent);
+    return buffer_or_string_memind_to_bytind (obj, i);
+  }
+}
+
+static Bufpos
+extent_endpoint_bufpos (EXTENT extent, int endp)
+{
+  assert (EXTENT_LIVE_P (extent));
+  assert (!extent_detached_p (extent));
+  {
+    Memind i = (endp) ? (extent_end (extent)) :
+      (extent_start (extent));
+    Lisp_Object obj = extent_object (extent);
+    return buffer_or_string_memind_to_bufpos (obj, i);
+  }
+}
+
+/* A change to an extent occurred that will change the display, so
+   notify redisplay.  Maybe also recurse over all the extent's
+   descendants. */
+
+static void
+extent_changed_for_redisplay (EXTENT extent, int descendants_too)
+{
+  Lisp_Object object;
+  Lisp_Object rest;
+
+  /* we could easily encounter a detached extent while traversing the
+     children, but we should never be able to encounter a dead extent. */
+  assert (EXTENT_LIVE_P (extent));
+
+  if (descendants_too)
+    {
+      Lisp_Object children = extent_children (extent);
+
+      if (!NILP (children))
+	{
+	  /* first mark all of the extent's children.  We will lose big-time
+	     if there are any circularities here, so we sure as hell better
+	     ensure that there aren't. */
+	  LIST_LOOP (rest, XWEAK_LIST_LIST (children))
+	    extent_changed_for_redisplay (XEXTENT (XCAR (rest)), 1);
+	}
+    }
+
+  /* now mark the extent itself. */
+  
+  object = extent_object (extent);
+
+  if (!BUFFERP (object) || extent_detached_p (extent))
+    /* #### Can changes to string extents affect redisplay?
+       I will have to think about this.  What about string glyphs?
+       Things in the modeline? etc. */
+    /* #### changes to string extents can certainly affect redisplay
+       if the extent is in some generated-modeline-string: when
+       we change an extent in generated-modeline-string, this changes
+       its parent, which is in `modeline-format', so we should
+       force the modeline to be updated.  But how to determine whether
+       a string is a `generated-modeline-string'?  Looping through
+       all buffers is not very efficient.  Should we add all
+       `generated-modeline-string' strings to a hashtable?
+       Maybe efficiency is not the greatest concern here and there's
+       no big loss in looping over the buffers. */
+    return;
+
+  {
+    struct buffer *b;
+    b = XBUFFER (object);
+    BUF_FACECHANGE (b)++;
+    MARK_EXTENTS_CHANGED;
+    buffer_extent_signal_changed_region (b,
+					 extent_endpoint_bufpos (extent, 0),
+					 extent_endpoint_bufpos (extent, 1));
+  }
+}
+
+/* A change to an extent occurred that will might affect redisplay.
+   This is called when properties such as the endpoints, the layout,
+   or the priority changes.  Redisplay will be affected only if
+   the extent has any displayable attributes. */
+
+static void
+extent_maybe_changed_for_redisplay (EXTENT extent, int descendants_too)
+{
+  /* Retrieve the ancestor for efficiency */
+  EXTENT anc = extent_ancestor (extent);
+  if (!NILP (extent_face (anc)) || !NILP (extent_begin_glyph (anc)) ||
+      !NILP (extent_end_glyph (anc)) || !NILP (extent_mouse_face (anc)) ||
+      !NILP (extent_invisible (anc)))
+    extent_changed_for_redisplay (extent, descendants_too);
+}
+
+static EXTENT
+make_extent_detached (Lisp_Object object)
+{
+  EXTENT extent = allocate_extent ();
+
+  assert (NILP (object) || STRINGP (object) ||
+	  (BUFFERP (object) && BUFFER_LIVE_P (XBUFFER (object))));
+  extent_object (extent) = object;
+  /* Now make sure the extent info exists. */
+  if (!NILP (object))
+    (void) buffer_or_string_extent_info_force (object);
+  return extent;
+}
+
+/* A "real" extent is any extent other than the internal (not-user-visible)
+   extents used by `map-extents'. */
+
+static EXTENT
+real_extent_at_forward (Extent_List *el, int pos, int endp)
+{
+  for (; pos < extent_list_num_els (el); pos++)
+    {
+      EXTENT e = extent_list_at (el, pos, endp);
+      if (!extent_internal_p (e))
+	return e;
+    }
+  return 0;
+}
+
+static EXTENT
+real_extent_at_backward (Extent_List *el, int pos, int endp)
+{
+  for (; pos >= 0; pos--)
+    {
+      EXTENT e = extent_list_at (el, pos, endp);
+      if (!extent_internal_p (e))
+	return e;
+    }
+  return 0;
+}
+
+static EXTENT
+extent_first (Lisp_Object obj)
+{
+  Extent_List *el = buffer_or_string_extent_list (obj);
+
+  if (!el)
+    return 0;
+  return real_extent_at_forward (el, 0, 0);
+}
+
+#ifdef DEBUG_XEMACS
+static EXTENT
+extent_e_first (Lisp_Object obj)
+{
+  Extent_List *el = buffer_or_string_extent_list (obj);
+
+  if (!el)
+    return 0;
+  return real_extent_at_forward (el, 0, 1);
+}
+#endif
+
+static EXTENT
+extent_next (EXTENT e)
+{
+  Extent_List *el = extent_extent_list (e);
+  int foundp;
+  int pos;
+
+  pos = extent_list_locate (el, e, 0, &foundp);
+  assert (foundp);
+  return real_extent_at_forward (el, pos+1, 0);
+}
+
+#ifdef DEBUG_XEMACS
+static EXTENT
+extent_e_next (EXTENT e)
+{
+  Extent_List *el = extent_extent_list (e);
+  int foundp;
+  int pos;
+
+  pos = extent_list_locate (el, e, 1, &foundp);
+  assert (foundp);
+  return real_extent_at_forward (el, pos+1, 1);
+}
+#endif
+
+static EXTENT
+extent_last (Lisp_Object obj)
+{
+  Extent_List *el = buffer_or_string_extent_list (obj);
+
+  if (!el)
+    return 0;
+  return real_extent_at_backward (el, extent_list_num_els (el) - 1, 0);
+}
+
+#ifdef DEBUG_XEMACS
+static EXTENT
+extent_e_last (Lisp_Object obj)
+{
+  Extent_List *el = buffer_or_string_extent_list (obj);
+
+  if (!el)
+    return 0;
+  return real_extent_at_backward (el, extent_list_num_els (el) - 1, 1);
+}
+#endif
+
+static EXTENT
+extent_previous (EXTENT e)
+{
+  Extent_List *el = extent_extent_list (e);
+  int foundp;
+  int pos;
+
+  pos = extent_list_locate (el, e, 0, &foundp);
+  assert (foundp);
+  return real_extent_at_backward (el, pos-1, 0);
+}
+
+#ifdef DEBUG_XEMACS
+static EXTENT
+extent_e_previous (EXTENT e)
+{
+  Extent_List *el = extent_extent_list (e);
+  int foundp;
+  int pos;
+
+  pos = extent_list_locate (el, e, 1, &foundp);
+  assert (foundp);
+  return real_extent_at_backward (el, pos-1, 1);
+}
+#endif
+
+static void
+extent_attach (EXTENT extent)
+{
+  Extent_List *el = extent_extent_list (extent);
+
+  extent_list_insert (el, extent);
+  soe_insert (extent_object (extent), extent);
+  /* only this extent changed */
+  extent_maybe_changed_for_redisplay (extent, 0);
+}
+
+static void
+extent_detach (EXTENT extent)
+{ 
+  Extent_List *el;
+
+  if (extent_detached_p (extent))
+    return;
+  el = extent_extent_list (extent);
+
+  /* call this before messing with the extent. */
+  extent_maybe_changed_for_redisplay (extent, 0);
+  extent_list_delete (el, extent);
+  soe_delete (extent_object (extent), extent);
+  set_extent_start (extent, -1);
+  set_extent_end (extent, -1);
+}
+
+/* ------------------------------- */
+/*        map-extents et al.       */
+/* ------------------------------- */
+
+/* Returns true iff map_extents() would visit the given extent.
+   See the comments at map_extents() for info on the overlap rule.
+   Assumes that all validation on the extent and buffer positions has
+   already been performed (see Fextent_in_region_p ()).
+ */
+static int
+extent_in_region_p (EXTENT extent, Bytind from, Bytind to,
+		    unsigned int flags)
+{
+  Lisp_Object obj = extent_object (extent);
+  Endpoint_Index start, end, exs, exe;
+  int start_open, end_open;
+  unsigned int all_extents_flags = flags & ME_ALL_EXTENTS_MASK;
+  unsigned int in_region_flags = flags & ME_IN_REGION_MASK;
+  int retval;
+
+  /* A zero-length region is treated as closed-closed. */
+  if (from == to)
+    {
+      flags |= ME_END_CLOSED;
+      flags &= ~ME_START_OPEN;
+    }
+
+  switch (all_extents_flags)
+    {
+    case ME_ALL_EXTENTS_CLOSED:
+      start_open = end_open = 0; break;
+    case ME_ALL_EXTENTS_OPEN:
+      start_open = end_open = 1; break;
+    case ME_ALL_EXTENTS_CLOSED_OPEN:
+      start_open = 0; end_open = 1; break;
+    case ME_ALL_EXTENTS_OPEN_CLOSED:
+      start_open = 1; end_open = 0; break;
+    default:
+      start_open = extent_start_open_p (extent);
+      end_open = extent_end_open_p (extent);
+      break;
+    }
+
+  /* So is a zero-length extent. */
+  if (extent_start (extent) == extent_end (extent))
+    start_open = end_open = 0;
+
+  start = buffer_or_string_bytind_to_startind (obj, from,
+					       flags & ME_START_OPEN);
+  end = buffer_or_string_bytind_to_endind (obj, to, ! (flags & ME_END_CLOSED));
+  exs = memind_to_startind (extent_start (extent), start_open);
+  exe = memind_to_endind (extent_end (extent), end_open);
+
+  /* It's easy to determine whether an extent lies *outside* the
+     region -- just determine whether it's completely before
+     or completely after the region.  Reject all such extents, so
+     we're now left with only the extents that overlap the region.
+   */
+
+  if (exs > end || exe < start)
+    return 0;
+
+  /* See if any further restrictions are called for. */
+  switch (in_region_flags)
+    {
+    case ME_START_IN_REGION:
+      retval = start <= exs && exs <= end; break;
+    case ME_END_IN_REGION:
+      retval = start <= exe && exe <= end; break;
+    case ME_START_AND_END_IN_REGION:
+      retval = start <= exs && exe <= end; break;
+    case ME_START_OR_END_IN_REGION:
+      retval = (start <= exs && exs <= end) || (start <= exe && exe <= end);
+      break;
+    default:
+      retval = 1; break;
+    }
+  return flags & ME_NEGATE_IN_REGION ? !retval : retval;
+}
+
+struct map_extents_struct
+{
+  Extent_List *el;
+  Extent_List_Marker *mkr;
+  EXTENT range;
+};
+
+static Lisp_Object
+map_extents_unwind (Lisp_Object obj)
+{
+  struct map_extents_struct *closure = 
+    (struct map_extents_struct *) get_opaque_ptr (obj);
+  free_opaque_ptr (obj);
+  if (closure->range)
+    extent_detach (closure->range);
+  if (closure->mkr)
+    extent_list_delete_marker (closure->el, closure->mkr);
+  return Qnil;
+}
+
+/* This is the guts of `map-extents' and the other functions that
+   map over extents.  In theory the operation of this function is
+   simple: just figure out what extents we're mapping over, and
+   call the function on each one of them in the range.  Unfortunately
+   there are a wide variety of things that the mapping function
+   might do, and we have to be very tricky to avoid getting messed
+   up.  Furthermore, this function needs to be very fast (it is
+   called multiple times every time text is inserted or deleted
+   from a buffer), and so we can't always afford the overhead of
+   dealing with all the possible things that the mapping function
+   might do; thus, there are many flags that can be specified
+   indicating what the mapping function might or might not do.
+
+   The result of all this is that this is the most complicated
+   function in this file.  Change it at your own risk!
+
+   A potential simplification to the logic below is to determine
+   all the extents that the mapping function should be called on
+   before any calls are actually made and save them in an array.
+   That introduces its own complications, however (the array
+   needs to be marked for garbage-collection, and a static array
+   cannot be used because map_extents() needs to be reentrant).
+   Furthermore, the results might be a little less sensible than
+   the logic below. */
+
+
+static void
+map_extents_bytind (Bytind from, Bytind to,
+		    int (*fn) (EXTENT extent, void *arg), void *arg,
+		    Lisp_Object obj, EXTENT after, unsigned int flags)
+{
+  Memind st, en; /* range we're mapping over */
+  EXTENT range = 0; /* extent for this, if ME_MIGHT_MODIFY_TEXT */
+  Extent_List *el = 0; /* extent list we're iterating over */
+  Extent_List_Marker *posm = 0; /* marker for extent list,
+				   if ME_MIGHT_MODIFY_EXTENTS */
+  /* count and struct for unwind-protect, if ME_MIGHT_THROW */
+  int count = 0;
+  struct map_extents_struct closure;
+
+#ifdef ERROR_CHECK_EXTENTS
+  assert (from <= to);
+  assert (from >= buffer_or_string_absolute_begin_byte (obj) &&
+	  from <= buffer_or_string_absolute_end_byte (obj) &&
+	  to >= buffer_or_string_absolute_begin_byte (obj) &&
+	  to <= buffer_or_string_absolute_end_byte (obj));
+#endif
+
+  if (after)
+    {
+      assert (EQ (obj, extent_object (after)));
+      assert (!extent_detached_p (after));
+    }
+
+  if (!buffer_or_string_extent_list (obj))
+    return;
+
+  st = buffer_or_string_bytind_to_memind (obj, from);
+  en = buffer_or_string_bytind_to_memind (obj, to);
+
+  if (flags & ME_MIGHT_MODIFY_TEXT)
+    {
+      /* The mapping function might change the text in the buffer,
+	 so make an internal extent to hold the range we're mapping
+	 over. */
+      range = make_extent_detached (obj);
+      set_extent_start (range, st);
+      set_extent_end (range, en);
+      range->flags.start_open = flags & ME_START_OPEN;
+      range->flags.end_open = !(flags & ME_END_CLOSED);
+      range->flags.internal = 1;
+      range->flags.detachable = 0;
+      extent_attach (range);
+    }
+
+  if (flags & ME_MIGHT_THROW)
+    {
+      /* The mapping function might throw past us so we need to use an
+	 unwind_protect() to eliminate the internal extent and range
+	 that we use. */
+      count = specpdl_depth ();
+      closure.range = range;
+      closure.mkr = 0;
+      record_unwind_protect (map_extents_unwind,
+			     make_opaque_ptr (&closure));
+    }
+
+  /* ---------- Figure out where we start and what direction
+                we move in.  This is the trickiest part of this
+		function. ---------- */
+
+  /* If ME_START_IN_REGION, ME_END_IN_REGION or ME_START_AND_END_IN_REGION
+     was specified and ME_NEGATE_IN_REGION was not specified, our job
+     is simple because of the presence of the display order and e-order.
+     (Note that theoretically do something similar for
+     ME_START_OR_END_IN_REGION, but that would require more trickiness
+     than it's worth to avoid hitting the same extent twice.)
+
+     In the general case, all the extents that overlap a range can be
+     divided into two classes: those whose start position lies within
+     the range (including the range's end but not including the
+     range's start), and those that overlap the start position,
+     i.e. those in the SOE for the start position.  Or equivalently,
+     the extents can be divided into those whose end position lies
+     within the range and those in the SOE for the end position.  Note
+     that for this purpose we treat both the range and all extents in
+     the buffer as closed on both ends.  If this is not what the ME_
+     flags specified, then we've mapped over a few too many extents,
+     but no big deal because extent_in_region_p() will filter them
+     out.   Ideally, we could move the SOE to the closer of the range's
+     two ends and work forwards or backwards from there.  However, in
+     order to make the semantics of the AFTER argument work out, we
+     have to always go in the same direction; so we choose to always
+     move the SOE to the start position.
+
+     When it comes time to do the SOE stage, we first call soe_move()
+     so that the SOE gets set up.  Note that the SOE might get
+     changed while we are mapping over its contents.  If we can
+     guarantee that the SOE won't get moved to a new position, we
+     simply need to put a marker in the SOE and we will track deletions
+     and insertions of extents in the SOE.  If the SOE might get moved,
+     however (this would happen as a result of a recursive invocation
+     of map-extents or a call to a redisplay-type function), then
+     trying to track its changes is hopeless, so we just keep a
+     marker to the first (or last) extent in the SOE and use that as
+     our bound.
+
+     Finally, if DONT_USE_SOE is defined, we don't use the SOE at all
+     and instead just map from the beginning of the buffer.  This is
+     used for testing purposes and allows the SOE to be calculated
+     using map_extents() instead of the other way around. */
+
+  {
+    int range_flag; /* ME_*_IN_REGION subset of flags */
+    int do_soe_stage = 0; /* Are we mapping over the SOE? */
+    /* Does the range stage map over start or end positions? */
+    int range_endp;
+    /* If type == 0, we include the start position in the range stage mapping.
+       If type == 1, we exclude the start position in the range stage mapping.
+       If type == 2, we begin at range_start_pos, an extent-list position.
+     */
+    int range_start_type = 0;
+    int range_start_pos = 0;
+    int stage;
+
+    range_flag = flags & ME_IN_REGION_MASK;
+    if ((range_flag == ME_START_IN_REGION ||
+	 range_flag == ME_START_AND_END_IN_REGION) &&
+	!(flags & ME_NEGATE_IN_REGION))
+      {
+	/* map over start position in [range-start, range-end].  No SOE
+	   stage. */
+	range_endp = 0;
+      }
+    else if (range_flag == ME_END_IN_REGION && !(flags & ME_NEGATE_IN_REGION))
+      {
+	/* map over end position in [range-start, range-end].  No SOE
+	   stage. */
+	range_endp = 1;
+      }
+    else
+      {
+	/* Need to include the SOE extents. */
+#ifdef DONT_USE_SOE
+	/* Just brute-force it: start from the beginning. */
+	range_endp = 0;
+	range_start_type = 2;
+	range_start_pos = 0;
+#else
+	Stack_Of_Extents *soe = buffer_or_string_stack_of_extents_force (obj);
+	int numsoe;
+	
+	/* Move the SOE to the closer end of the range.  This dictates
+	   whether we map over start positions or end positions. */
+	range_endp = 0;
+	soe_move (obj, st);
+	numsoe = extent_list_num_els (soe->extents);
+	if (numsoe)
+	  {
+	    if (flags & ME_MIGHT_MOVE_SOE)
+	      {
+		int foundp;
+		/* Can't map over SOE, so just extend range to cover the
+		   SOE. */
+		EXTENT e = extent_list_at (soe->extents, 0, 0);
+		range_start_pos =
+		  extent_list_locate (buffer_or_string_extent_list (obj), e, 0,
+				      &foundp);
+		assert (foundp);
+		range_start_type = 2;
+	      }
+	    else
+	      {
+		/* We can map over the SOE. */
+		do_soe_stage = 1;
+		range_start_type = 1;
+	      }
+	  }
+	else
+	  {
+	    /* No extents in the SOE to map over, so we act just as if
+	       ME_START_IN_REGION or ME_END_IN_REGION was specified.
+	       RANGE_ENDP already specified so no need to do anything else. */
+	  }
+      }
+#endif
+      
+  /* ---------- Now loop over the extents. ---------- */
+
+    /* We combine the code for the two stages because much of it
+       overlaps. */
+    for (stage = 0; stage < 2; stage++)
+      {
+	int pos = 0; /* Position in extent list */
+
+	/* First set up start conditions */
+	if (stage == 0)
+	  { /* The SOE stage */
+	    if (!do_soe_stage)
+	      continue;
+	    el = buffer_or_string_stack_of_extents_force (obj)->extents;
+	    /* We will always be looping over start extents here. */
+	    assert (!range_endp);
+	    pos = 0;
+	  }
+	else
+	  { /* The range stage */
+	    el = buffer_or_string_extent_list (obj);
+	    switch (range_start_type)
+	      {
+	      case 0:
+		pos = extent_list_locate_from_pos (el, st, range_endp);
+		break;
+	      case 1:
+		pos = extent_list_locate_from_pos (el, st + 1, range_endp);
+		break;
+	      case 2:
+		pos = range_start_pos;
+		break;
+	      }
+	  }
+
+	if (flags & ME_MIGHT_MODIFY_EXTENTS)
+	  {
+	    /* Create a marker to track changes to the extent list */
+	    if (posm)
+	      /* Delete the marker used in the SOE stage. */
+	      extent_list_delete_marker
+		(buffer_or_string_stack_of_extents_force (obj)->extents, posm);
+	    posm = extent_list_make_marker (el, pos, range_endp);
+	    /* tell the unwind function about the marker. */
+	    closure.el = el;
+	    closure.mkr = posm;
+	  }
+
+	/* Now loop! */
+	for (;;)
+	  {
+	    EXTENT e;
+	    Lisp_Object obj2;
+
+	    /* ----- update position in extent list
+	             and fetch next extent ----- */
+
+	    if (posm)
+	      /* fetch POS again to track extent insertions or deletions */
+	      pos = extent_list_marker_pos (el, posm);
+	    if (pos >= extent_list_num_els (el))
+	      break;
+	    e = extent_list_at (el, pos, range_endp);
+	    pos++;
+	    if (posm)
+	      /* now point the marker to the next one we're going to process.
+		 This ensures graceful behavior if this extent is deleted. */
+	      extent_list_move_marker (el, posm, pos);
+
+	    /* ----- deal with internal extents ----- */
+
+	    if (extent_internal_p (e))
+	      {
+		if (!(flags & ME_INCLUDE_INTERNAL))
+		  continue;
+		else if (e == range)
+		  {
+		    /* We're processing internal extents and we've
+		       come across our own special range extent.
+		       (This happens only in adjust_extents*() and
+		       process_extents*(), which handle text
+		       insertion and deletion.) We need to omit
+		       processing of this extent; otherwise
+		       we will probably end up prematurely
+		       terminating this loop. */
+		    continue;
+		  }
+	      }
+
+	    /* ----- deal with AFTER condition ----- */
+
+	    if (after)
+	      {
+		/* if e > after, then we can stop skipping extents. */
+		if (EXTENT_LESS (after, e))
+		  after = 0;
+		else /* otherwise, skip this extent. */
+		  continue;
+	      }
+
+	    /* ----- stop if we're completely outside the range ----- */
+
+	    /* fetch ST and EN again to track text insertions or deletions */
+	    if (range)
+	      {
+		st = extent_start (range);
+		en = extent_end (range);
+	      }
+	    if (extent_endpoint (e, range_endp) > en)
+	      {
+		/* Can't be mapping over SOE because all extents in
+		   there should overlap ST */
+		assert (stage == 1);
+		break;
+	      }
+
+	    /* ----- Now actually call the function ----- */
+
+	    obj2 = extent_object (e);
+	    if (extent_in_region_p (e,
+				    buffer_or_string_memind_to_bytind (obj2,
+								       st),
+				    buffer_or_string_memind_to_bytind (obj2,
+								       en),
+				    flags))
+	      {
+		if ((*fn)(e, arg))
+		  {
+		    /* Function wants us to stop mapping. */
+		    stage = 1; /* so outer for loop will terminate */
+		    break;
+		  }
+	      }
+	  }
+      }
+  /* ---------- Finished looping. ---------- */
+  }
+
+  if (flags & ME_MIGHT_THROW)
+    /* This deletes the range extent and frees the marker. */
+    unbind_to (count, Qnil);
+  else
+    {
+      /* Delete them ourselves */
+      if (range)
+	extent_detach (range);
+      if (posm)
+	extent_list_delete_marker (el, posm);
+    }
+}
+
+void
+map_extents (Bufpos from, Bufpos to, int (*fn) (EXTENT extent, void *arg),
+	     void *arg, Lisp_Object obj, EXTENT after, unsigned int flags)
+{
+  map_extents_bytind (buffer_or_string_bufpos_to_bytind (obj, from),
+		      buffer_or_string_bufpos_to_bytind (obj, to), fn, arg,
+		      obj, after, flags);
+}
+
+/* ------------------------------- */
+/*         adjust_extents()        */
+/* ------------------------------- */
+
+/* Add AMOUNT to all extent endpoints in the range (FROM, TO].  This
+   happens whenever the gap is moved or (under Mule) a character in a
+   string is substituted for a different-length one.  The reason for
+   this is that extent endpoints behave just like markers (all memory
+   indices do) and this adjustment correct for markers -- see
+   adjust_markers().  Note that it is important that we visit all
+   extent endpoints in the range, irrespective of whether the
+   endpoints are open or closed.
+
+   We could use map_extents() for this (and in fact the function
+   was originally written that way), but the gap is in an incoherent
+   state when this function is called and this function plays
+   around with extent endpoints without detaching and reattaching
+   the extents (this is provably correct and saves lots of time),
+   so for safety we make it just look at the extent lists directly. */
+
+void
+adjust_extents (Lisp_Object obj, Memind from, Memind to, int amount)
+{
+  int endp;
+  int pos;
+  int startpos[2];
+  Extent_List *el;
+  Stack_Of_Extents *soe;
+
+#ifdef ERROR_CHECK_EXTENTS
+  sledgehammer_extent_check (obj);
+#endif
+  el = buffer_or_string_extent_list (obj);
+
+  if (!el)
+    return;
+  /* IMPORTANT! Compute the starting positions of the extents to
+     modify BEFORE doing any modification!  Otherwise the starting
+     position for the second time through the loop might get
+     incorrectly calculated (I got bit by this bug real bad). */
+  startpos[0] = extent_list_locate_from_pos (el, from+1, 0);
+  startpos[1] = extent_list_locate_from_pos (el, from+1, 1);
+  for (endp = 0; endp < 2; endp++)
+    {
+      for (pos = startpos[endp]; pos < extent_list_num_els (el);
+	   pos++)
+	{
+	  EXTENT e = extent_list_at (el, pos, endp);
+	  if (extent_endpoint (e, endp) > to)
+	    break;
+	  set_extent_endpoint (e,
+			       do_marker_adjustment (extent_endpoint (e, endp),
+						     from, to, amount),
+			       endp);
+	}
+    }
+
+  /* The index for the buffer's SOE is a memory index and thus
+     needs to be adjusted like a marker. */
+  soe = buffer_or_string_stack_of_extents (obj);
+  if (soe && soe->pos >= 0)
+    soe->pos = do_marker_adjustment (soe->pos, from, to, amount);
+}
+
+/* ------------------------------- */
+/*  adjust_extents_for_deletion()  */
+/* ------------------------------- */
+
+struct adjust_extents_for_deletion_arg
+{
+  extent_dynarr *list;
+};
+
+static int
+adjust_extents_for_deletion_mapper (EXTENT extent, void *arg)
+{
+  struct adjust_extents_for_deletion_arg *closure =
+    (struct adjust_extents_for_deletion_arg *) arg;
+
+  Dynarr_add (closure->list, extent);
+  return 0; /* continue mapping */
+}
+
+/* For all extent endpoints in the range (FROM, TO], move them to the beginning
+   of the new gap.   Note that it is important that we visit all extent
+   endpoints in the range, irrespective of whether the endpoints are open or
+   closed.
+
+   This function deals with weird stuff such as the fact that extents
+   may get reordered.
+
+   There is no string correspondent for this because you can't
+   delete characters from a string.
+ */
+
+void
+adjust_extents_for_deletion (Lisp_Object object, Bytind from,
+			     Bytind to, int gapsize, int numdel)
+{
+  struct adjust_extents_for_deletion_arg closure;
+  int i;
+  Memind oldsoe, newsoe;
+  Stack_Of_Extents *soe = buffer_or_string_stack_of_extents (object);
+
+#ifdef ERROR_CHECK_EXTENTS
+  sledgehammer_extent_check (object);
+#endif
+  closure.list = (extent_dynarr *) Dynarr_new (EXTENT);
+
+  /* We're going to be playing weird games below with extents and the SOE
+     and such, so compute the list now of all the extents that we're going
+     to muck with.  If we do the mapping and adjusting together, things can
+     get all screwed up. */
+
+  map_extents_bytind (from, to, adjust_extents_for_deletion_mapper,
+		      (void *) &closure, object, 0,
+		      /* extent endpoints move like markers regardless
+			 of their open/closeness. */
+		      ME_ALL_EXTENTS_CLOSED | ME_END_CLOSED |
+		      ME_START_OR_END_IN_REGION | ME_INCLUDE_INTERNAL);
+
+  /*
+    Old and new values for the SOE's position. (It gets adjusted
+    like a marker, just like extent endpoints.)
+  */
+
+  if (soe)
+    {
+      oldsoe = soe->pos;
+      if (soe->pos >= 0)
+	newsoe = do_marker_adjustment (soe->pos,
+				       (Memind) (to + gapsize),
+				       (Memind) (to + gapsize),
+				       - numdel - gapsize);
+      else
+	newsoe = soe->pos;
+    }
+
+  for (i = 0; i < Dynarr_length (closure.list); i++)
+    {
+      EXTENT extent = Dynarr_at (closure.list, i);
+      Memind new_start, new_end;
+
+      /* do_marker_adjustment() will not adjust values that should not be
+	 adjusted.  We're passing the same funky arguments to
+	 do_marker_adjustment() as buffer_delete_range() does. */
+      new_start =
+	do_marker_adjustment (extent_start (extent),
+			      (Memind) (to + gapsize),
+			      (Memind) (to + gapsize),
+			      - numdel - gapsize);
+      new_end =
+	do_marker_adjustment (extent_end (extent),
+			      (Memind) (to + gapsize),
+			      (Memind) (to + gapsize),
+			      - numdel - gapsize);
+
+      /* We need to be very careful here so that the SOE doesn't get
+	 corrupted.  We are shrinking extents out of the deleted region
+	 and simultaneously moving the SOE's pos out of the deleted
+	 region, so the SOE should contain the same extents at the end
+	 as at the beginning.  However, extents may get reordered
+	 by this process, so we have to operate by pulling the extents
+	 out of the buffer and SOE, changing their bounds, and then
+	 reinserting them.  In order for the SOE not to get screwed up,
+	 we have to make sure that the SOE's pos points to its old
+	 location whenever we pull an extent out, and points to its
+	 new location whenever we put the extent back in.
+       */
+
+      if (new_start != extent_start (extent) ||
+	  new_end != extent_end (extent))
+	{
+	  extent_detach (extent);
+	  set_extent_start (extent, new_start);
+	  set_extent_end (extent, new_end);
+	  if (soe)
+	    soe->pos = newsoe;
+	  extent_attach (extent);
+	  if (soe)
+	    soe->pos = oldsoe;
+	}
+    }
+
+  if (soe)
+    soe->pos = newsoe;
+
+#ifdef ERROR_CHECK_EXTENTS
+  sledgehammer_extent_check (object);
+#endif
+  Dynarr_free (closure.list);
+}
+
+/* ------------------------------- */
+/*         extent fragments        */
+/* ------------------------------- */
+
+/* Imagine that the buffer is divided up into contiguous,
+   nonoverlapping "runs" of text such that no extent
+   starts or ends within a run (extents that abut the
+   run don't count).
+
+   An extent fragment is a structure that holds data about
+   the run that contains a particular buffer position (if
+   the buffer position is at the junction of two runs, the
+   run after the position is used) -- the beginning and
+   end of the run, a list of all of the extents in that
+   run, the "merged face" that results from merging all of
+   the faces corresponding to those extents, the begin and
+   end glyphs at the beginning of the run, etc.  This is
+   the information that redisplay needs in order to
+   display this run.
+
+   Extent fragments have to be very quick to update to
+   a new buffer position when moving linearly through
+   the buffer.  They rely on the stack-of-extents code,
+   which does the heavy-duty algorithmic work of determining
+   which extents overly a particular position. */
+
+/* This function returns the position of the beginning of
+   the first run that begins after POS, or returns POS if
+   there are no such runs. */
+
+static Bytind
+extent_find_end_of_run (Lisp_Object obj, Bytind pos, int outside_accessible)
+{
+  Extent_List *sel;
+  Extent_List *bel = buffer_or_string_extent_list (obj);
+  Bytind pos1, pos2;
+  int elind1, elind2;
+  Memind mempos = buffer_or_string_bytind_to_memind (obj, pos);
+  Bytind limit = outside_accessible ?
+    buffer_or_string_absolute_end_byte (obj) :
+      buffer_or_string_accessible_end_byte (obj);
+
+  if (!bel)
+    return limit;
+
+  sel = buffer_or_string_stack_of_extents_force (obj)->extents;
+  soe_move (obj, mempos);
+
+  /* Find the first start position after POS. */
+  elind1 = extent_list_locate_from_pos (bel, mempos+1, 0);
+  if (elind1 < extent_list_num_els (bel))
+    pos1 = buffer_or_string_memind_to_bytind
+      (obj, extent_start (extent_list_at (bel, elind1, 0)));
+  else
+    pos1 = limit;
+
+  /* Find the first end position after POS.  The extent corresponding
+     to this position is either in the SOE or is greater than or
+     equal to POS1, so we just have to look in the SOE. */
+  elind2 = extent_list_locate_from_pos (sel, mempos+1, 1);
+  if (elind2 < extent_list_num_els (sel))
+    pos2 = buffer_or_string_memind_to_bytind
+      (obj, extent_end (extent_list_at (sel, elind2, 1)));
+  else
+    pos2 = limit;
+
+  return min (min (pos1, pos2), limit);
+}
+
+static Bytind
+extent_find_beginning_of_run (Lisp_Object obj, Bytind pos,
+			      int outside_accessible)
+{
+  Extent_List *sel;
+  Extent_List *bel = buffer_or_string_extent_list (obj);
+  Bytind pos1, pos2;
+  int elind1, elind2;
+  Memind mempos = buffer_or_string_bytind_to_memind (obj, pos);
+  Bytind limit = outside_accessible ?
+    buffer_or_string_absolute_begin_byte (obj) :
+      buffer_or_string_accessible_begin_byte (obj);
+
+  if (!bel)
+    return limit;
+
+  sel = buffer_or_string_stack_of_extents_force (obj)->extents;
+  soe_move (obj, mempos);
+
+  /* Find the first end position before POS. */
+  elind1 = extent_list_locate_from_pos (bel, mempos, 1);
+  if (elind1 > 0)
+    pos1 = buffer_or_string_memind_to_bytind
+      (obj, extent_end (extent_list_at (bel, elind1 - 1, 1)));
+  else
+    pos1 = limit;
+
+  /* Find the first start position before POS.  The extent corresponding
+     to this position is either in the SOE or is less than or
+     equal to POS1, so we just have to look in the SOE. */
+  elind2 = extent_list_locate_from_pos (sel, mempos, 0);
+  if (elind2 > 0)
+    pos2 = buffer_or_string_memind_to_bytind
+      (obj, extent_start (extent_list_at (sel, elind2 - 1, 0)));
+  else
+    pos2 = limit;
+
+  return max (max (pos1, pos2), limit);
+}
+
+struct extent_fragment *
+extent_fragment_new (Lisp_Object buffer_or_string, struct frame *frm)
+{
+  struct extent_fragment *ef = (struct extent_fragment *)
+    xmalloc (sizeof (struct extent_fragment));
+
+  memset (ef, 0, sizeof (*ef));
+  ef->object = buffer_or_string;
+  ef->frm = frm;
+  ef->extents = Dynarr_new (EXTENT);
+  ef->begin_glyphs = Dynarr_new (struct glyph_block);
+  ef->end_glyphs = Dynarr_new (struct glyph_block);
+
+  return ef;
+}
+
+void
+extent_fragment_delete (struct extent_fragment *ef)
+{
+  Dynarr_free (ef->extents);
+  Dynarr_free (ef->begin_glyphs);
+  Dynarr_free (ef->end_glyphs);
+  xfree (ef);
+}
+
+static int
+extent_priority_sort_function (const void *humpty, const void *dumpty)
+{
+  CONST EXTENT foo = * (CONST EXTENT *) humpty;
+  CONST EXTENT bar = * (CONST EXTENT *) dumpty;
+  if (extent_priority (foo) < extent_priority (bar))
+    return -1;
+  return (extent_priority (foo) > extent_priority (bar));
+}
+
+static void
+extent_fragment_sort_by_priority (extent_dynarr *extarr)
+{
+  int i;
+
+  /* Sort our copy of the stack by extent_priority.  We use a bubble
+     sort here because it's going to be faster than qsort() for small
+     numbers of extents (less than 10 or so), and 99.999% of the time
+     there won't ever be more extents than this in the stack. */
+  if (Dynarr_length (extarr) < 10)
+    {
+      for (i = 1; i < Dynarr_length (extarr); i++)
+	{
+	  int j = i - 1;
+	  while (j >= 0 &&
+		 (extent_priority (Dynarr_at (extarr, j)) >
+		  extent_priority (Dynarr_at (extarr, j+1))))
+	    {
+	      EXTENT tmp = Dynarr_at (extarr, j);
+	      Dynarr_at (extarr, j) = Dynarr_at (extarr, j+1);
+	      Dynarr_at (extarr, j+1) = tmp;
+	      j--;
+	    }
+	}
+    }
+  else
+    /* But some loser programs mess up and may create a large number
+       of extents overlapping the same spot.  This will result in
+       catastrophic behavior if we use the bubble sort above. */
+    qsort (Dynarr_atp (extarr, 0), Dynarr_length (extarr),
+	   sizeof (EXTENT), extent_priority_sort_function);
+}
+
+/* If PROP is the `invisible' property of an extent,
+   this is 1 if the extent should be treated as invisible.  */
+
+#define EXTENT_PROP_MEANS_INVISIBLE(buf, prop)			\
+  (EQ (buf->invisibility_spec, Qt)				\
+   ? ! NILP (prop)						\
+   : invisible_p (prop, buf->invisibility_spec))
+
+/* If PROP is the `invisible' property of a extent,
+   this is 1 if the extent should be treated as invisible
+   and should have an ellipsis.  */
+
+#define EXTENT_PROP_MEANS_INVISIBLE_WITH_ELLIPSIS(buf, prop)	\
+  (EQ (buf->invisibility_spec, Qt)				\
+   ? 0								\
+   : invisible_ellipsis_p (prop, buf->invisibility_spec))
+
+/* This is like a combination of memq and assq.
+   Return 1 if PROPVAL appears as an element of LIST
+   or as the car of an element of LIST.
+   If PROPVAL is a list, compare each element against LIST
+   in that way, and return 1 if any element of PROPVAL is found in LIST.
+   Otherwise return 0.
+   This function cannot quit.  */
+
+static int
+invisible_p (REGISTER Lisp_Object propval, Lisp_Object list)
+{
+  REGISTER Lisp_Object tail, proptail;
+  for (tail = list; CONSP (tail); tail = XCDR (tail))
+    {
+      REGISTER Lisp_Object tem;
+      tem = XCAR (tail);
+      if (EQ (propval, tem))
+	return 1;
+      if (CONSP (tem) && EQ (propval, XCAR (tem)))
+	return 1;
+    }
+  if (CONSP (propval))
+    for (proptail = propval; CONSP (proptail);
+	 proptail = XCDR (proptail))
+      {
+	Lisp_Object propelt;
+	propelt = XCAR (proptail);
+	for (tail = list; CONSP (tail); tail = XCDR (tail))
+	  {
+	    REGISTER Lisp_Object tem;
+	    tem = XCAR (tail);
+	    if (EQ (propelt, tem))
+	      return 1;
+	    if (CONSP (tem) && EQ (propelt, XCAR (tem)))
+	      return 1;
+	  }
+      }
+  return 0;
+}
+
+/* Return 1 if PROPVAL appears as the car of an element of LIST
+   and the cdr of that element is non-nil.
+   If PROPVAL is a list, check each element of PROPVAL in that way,
+   and the first time some element is found,
+   return 1 if the cdr of that element is non-nil.
+   Otherwise return 0.
+   This function cannot quit.  */
+
+static int
+invisible_ellipsis_p (REGISTER Lisp_Object propval, Lisp_Object list)
+{
+  REGISTER Lisp_Object tail, proptail;
+  for (tail = list; CONSP (tail); tail = XCDR (tail))
+    {
+      REGISTER Lisp_Object tem;
+      tem = XCAR (tail);
+      if (CONSP (tem) && EQ (propval, XCAR (tem)))
+	return ! NILP (XCDR (tem));
+    }
+  if (CONSP (propval))
+    for (proptail = propval; CONSP (proptail);
+	 proptail = XCDR (proptail))
+      {
+	Lisp_Object propelt;
+	propelt = XCAR (proptail);
+	for (tail = list; CONSP (tail); tail = XCDR (tail))
+	  {
+	    REGISTER Lisp_Object tem;
+	    tem = XCAR (tail);
+	    if (CONSP (tem) && EQ (propelt, XCAR (tem)))
+	      return ! NILP (XCDR (tem));
+	  }
+      }
+  return 0;
+}
+
+face_index
+extent_fragment_update (struct window *w, struct extent_fragment *ef,
+			Bytind pos)
+{
+  int i;
+  Extent_List *sel =
+    buffer_or_string_stack_of_extents_force (ef->object)->extents;
+  EXTENT lhe = 0;
+  struct extent dummy_lhe_extent;
+  Memind mempos = buffer_or_string_bytind_to_memind (ef->object, pos);
+
+#ifdef ERROR_CHECK_EXTENTS
+  assert (pos >= buffer_or_string_accessible_begin_byte (ef->object)
+	  && pos <= buffer_or_string_accessible_end_byte (ef->object));
+#endif
+
+  Dynarr_reset (ef->extents);
+  Dynarr_reset (ef->begin_glyphs);
+  Dynarr_reset (ef->end_glyphs);
+
+  ef->previously_invisible = ef->invisible;
+  if (ef->invisible)
+    {
+      if (ef->invisible_ellipses)
+	ef->invisible_ellipses_already_displayed = 1;
+    }
+  else
+    ef->invisible_ellipses_already_displayed = 0;
+  ef->invisible = 0;
+  ef->invisible_ellipses = 0;
+
+  /* Set up the begin and end positions. */
+  ef->pos = pos;
+  ef->end = extent_find_end_of_run (ef->object, pos, 0);
+
+  /* Note that extent_find_end_of_run() already moved the SOE for us. */
+  /* soe_move (ef->object, mempos); */
+
+  /* Determine the begin glyphs at POS. */
+  for (i = 0; i < extent_list_num_els (sel); i++)
+    {
+      EXTENT e = extent_list_at (sel, i, 0);
+      if (extent_start (e) == mempos && !NILP (extent_begin_glyph (e)))
+	{
+	  Lisp_Object glyph = extent_begin_glyph (e);
+	  struct glyph_block gb;
+	  
+	  gb.glyph = glyph;
+	  gb.extent = Qnil;
+	  XSETEXTENT (gb.extent, e);
+	  Dynarr_add (ef->begin_glyphs, gb);
+	}
+    }
+  
+  /* Determine the end glyphs at POS. */
+  for (i = 0; i < extent_list_num_els (sel); i++)
+    {
+      EXTENT e = extent_list_at (sel, i, 1);
+      if (extent_end (e) == mempos && !NILP (extent_end_glyph (e)))
+	{
+	  Lisp_Object glyph = extent_end_glyph (e);
+	  struct glyph_block gb;
+	  
+	  gb.glyph = glyph;
+	  gb.extent = Qnil;
+	  XSETEXTENT (gb.extent, e);
+	  Dynarr_add (ef->end_glyphs, gb);
+	}
+    }
+
+  /* We tried determining all the charsets used in the run here,
+     but that fails even if we only do the current line -- display
+     tables or non-printable characters might cause other charsets
+     to be used. */
+
+  /* Determine whether the last-highlighted-extent is present. */
+  if (EXTENTP (Vlast_highlighted_extent))
+    lhe = XEXTENT (Vlast_highlighted_extent);
+
+  /* Now add all extents that overlap the character after POS and
+     have a non-nil face.  Also check if the character is invisible. */
+  for (i = 0; i < extent_list_num_els (sel); i++)
+    {
+      EXTENT e = extent_list_at (sel, i, 0);
+      if (extent_end (e) > mempos)
+	{
+	  Lisp_Object invis_prop = extent_invisible (e);
+
+	  if (!NILP (invis_prop))
+	    {
+	      if (!BUFFERP (ef->object))
+		/* #### no `string-invisibility-spec' */
+		ef->invisible = 1;
+	      else
+		{
+		  if (!ef->invisible_ellipses_already_displayed &&
+		      EXTENT_PROP_MEANS_INVISIBLE_WITH_ELLIPSIS
+		      (XBUFFER (ef->object), invis_prop))
+		    {
+		      ef->invisible = 1;
+		      ef->invisible_ellipses = 1;
+		    }
+		  else if (EXTENT_PROP_MEANS_INVISIBLE
+			   (XBUFFER (ef->object), invis_prop))
+		    ef->invisible = 1;
+		}
+	    }
+
+	  /* Remember that one of the extents in the list might be our
+	     dummy extent representing the highlighting that is
+	     attached to some other extent that is currently
+	     mouse-highlighted.  When an extent is mouse-highlighted,
+	     it is as if there are two extents there, of potentially
+	     different priorities: the extent being highlighted, with
+	     whatever face and priority it has; and an ephemeral
+	     extent in the `mouse-face' face with
+	     `mouse-highlight-priority'.
+	     */
+
+	  if (!NILP (extent_face (e)))
+	    Dynarr_add (ef->extents, e);
+	  if (e == lhe)
+	    {
+	      /* memset isn't really necessary; we only deref `priority'
+		 and `face' */
+	      memset (&dummy_lhe_extent, 0, sizeof (dummy_lhe_extent));
+	      set_extent_priority (&dummy_lhe_extent,
+				   mouse_highlight_priority);
+	      extent_face (&dummy_lhe_extent) = extent_mouse_face (lhe);
+	      Dynarr_add (ef->extents, &dummy_lhe_extent);
+	    }
+	}
+    }
+
+  extent_fragment_sort_by_priority (ef->extents);
+
+  /* Now merge the faces together into a single face.  The code to
+     do this is in faces.c because it involves manipulating faces. */
+  return get_extent_fragment_face_cache_index (w, ef);
+}	  
+
+
+/************************************************************************/
+/*	  	        extent-object methods				*/
+/************************************************************************/
+
+/* These are the basic helper functions for handling the allocation of
+   extent objects.  They are similar to the functions for other
+   lrecord objects.  allocate_extent() is in alloc.c, not here. */
+
+static Lisp_Object mark_extent (Lisp_Object, void (*) (Lisp_Object));
+static int extent_equal (Lisp_Object, Lisp_Object, int depth);
+static unsigned long extent_hash (Lisp_Object obj, int depth);
+static void print_extent (Lisp_Object obj, Lisp_Object printcharfun,
+			  int escapeflag);
+static Lisp_Object extent_getprop (Lisp_Object obj, Lisp_Object prop);
+static int extent_putprop (Lisp_Object obj, Lisp_Object prop,
+			   Lisp_Object value);
+static int extent_remprop (Lisp_Object obj, Lisp_Object prop);
+static Lisp_Object extent_plist (Lisp_Object obj);
+
+DEFINE_BASIC_LRECORD_IMPLEMENTATION_WITH_PROPS ("extent", extent,
+						mark_extent,
+						print_extent,
+						/* NOTE: If you declare a
+						   finalization method here,
+						   it will NOT be called.
+						   Shaft city. */
+						0,
+						extent_equal, extent_hash,
+						extent_getprop, extent_putprop,
+						extent_remprop, extent_plist,
+						struct extent);
+
+static Lisp_Object
+mark_extent (Lisp_Object obj, void (*markobj) (Lisp_Object))
+{
+  struct extent *extent = XEXTENT (obj);
+
+  ((markobj) (extent_object (extent)));
+  ((markobj) (extent_no_chase_normal_field (extent, face)));
+  return (extent->plist);
+}
+
+static char *
+print_extent_1 (char *buf, Lisp_Object extent_obj)
+{
+  EXTENT ext = XEXTENT (extent_obj);
+  EXTENT anc = extent_ancestor (ext);
+  char *bp = buf;
+  Lisp_Object tail;
+
+  /* Retrieve the ancestor and use it, for faster retrieval of properties */
+
+  if (!NILP (extent_begin_glyph (anc))) *bp++ = '*';
+  *bp++ = (extent_start_open_p (anc) ? '(': '[');
+  if (extent_detached_p (ext))
+    sprintf (bp, "detached");
+  else
+    {
+      Bufpos from = XINT (Fextent_start_position (extent_obj));
+      Bufpos to = XINT (Fextent_end_position (extent_obj));
+      sprintf (bp, "%d, %d", from, to);
+    }
+  bp += strlen (bp);
+  *bp++ = (extent_end_open_p (anc) ? ')': ']');
+  if (!NILP (extent_end_glyph (anc))) *bp++ = '*';
+  *bp++ = ' ';
+
+  if (!NILP (extent_read_only (anc))) *bp++ = '%';
+  if (!NILP (extent_mouse_face (anc))) *bp++ = 'H';
+  if (extent_unique_p (anc)) *bp++ = 'U';
+  else if (extent_replicating_p (anc)) *bp++ = 'R';
+  else if (extent_duplicable_p (anc)) *bp++ = 'D';
+  if (!NILP (extent_invisible (anc))) *bp++ = 'I';
+
+  if (!NILP (extent_read_only (anc)) || !NILP (extent_mouse_face (anc)) ||
+      extent_unique_p (anc) || extent_replicating_p (anc) ||
+      extent_duplicable_p (anc) || !NILP (extent_invisible (anc)))
+    *bp++ = ' ';
+
+  tail = extent_plist_slot (anc);
+
+  for (; !NILP (tail); tail = Fcdr (Fcdr (tail)))
+    {
+      struct Lisp_String *k = XSYMBOL (XCAR (tail))->name;
+      Lisp_Object v = XCAR (XCDR (tail));
+      if (NILP (v)) continue;
+      memcpy (bp, (char *) string_data (k), string_length (k));
+      bp += string_length (k);
+      *bp++ = ' ';
+    }
+
+  sprintf (bp, "0x%lx", (long) ext);
+  bp += strlen (bp);
+
+  *bp++ = 0;
+  return buf;
+}
+
+static void
+print_extent (Lisp_Object obj, Lisp_Object printcharfun, int escapeflag)
+{
+  char buf2[256];
+
+  if (escapeflag)
+    {
+      CONST char *title = "";
+      CONST char *name = "";
+      CONST char *posttitle = "";
+      Lisp_Object obj2 = Qnil;
+	  
+      /* Destroyed extents have 't' in the object field, causing
+	 extent_object() to abort (maybe). */
+      if (EXTENT_LIVE_P (XEXTENT (obj)))
+	obj2 = extent_object (XEXTENT (obj));
+      
+      if (NILP (obj2))
+	title = "no buffer";
+      else if (BUFFERP (obj2))
+	{
+	  if (BUFFER_LIVE_P (XBUFFER (obj2)))
+	    {
+	      title = "buffer ";
+	      name = (char *) string_data (XSTRING (XBUFFER (obj2)->name));
+	    }
+	  else
+	    {
+	      title = "Killed Buffer";
+	      name = "";
+	    }
+	}
+      else
+	{
+	  assert (STRINGP (obj2));
+	  title = "string \"";
+	  posttitle = "\"";
+	  name = (char *) string_data (XSTRING (obj2));
+	}
+      
+      if (print_readably)
+	{
+	  if (!EXTENT_LIVE_P (XEXTENT (obj)))
+	    error ("printing unreadable object #<destroyed extent>");
+	  else
+	    error ("printing unreadable object #<extent %s>",
+		   print_extent_1 (buf2, obj));
+	}
+      
+      if (!EXTENT_LIVE_P (XEXTENT (obj)))
+	write_c_string ("#<destroyed extent", printcharfun);
+      else
+	{
+	  char buf[256];
+	  write_c_string ("#<extent ", printcharfun);
+	  if (extent_detached_p (XEXTENT (obj)))
+	    sprintf (buf, "%s from %s%s%s",
+		     print_extent_1 (buf2, obj), title, name, posttitle);
+	  else
+	    sprintf (buf, "%s in %s%s%s",
+		     print_extent_1 (buf2, obj),
+		     title, name, posttitle);
+	  write_c_string (buf, printcharfun);
+	}
+    }
+  else
+    {
+      if (print_readably)
+	error ("printing unreadable object #<extent>");
+      write_c_string ("#<extent", printcharfun);
+    }
+  write_c_string (">", printcharfun);
+}
+
+static int
+properties_equal (EXTENT e1, EXTENT e2, int depth)
+{
+  /* When this function is called, all indirections have been followed.
+     Thus, the indirection checks in the various macros below will not
+     amount to anything, and could be removed.  However, the time
+     savings would probably not be significant. */
+  if (!(EQ (extent_face (e1), extent_face (e2)) &&
+	extent_priority (e1) == extent_priority (e2) &&
+	internal_equal (extent_begin_glyph (e1), extent_begin_glyph (e2),
+			depth + 1) &&
+	internal_equal (extent_end_glyph (e1), extent_end_glyph (e2),
+			depth + 1)))
+    return 0;
+
+  /* compare the bit flags. */
+  {
+    /* The has_aux field should not be relevant. */
+    int e1_has_aux = e1->flags.has_aux;
+    int e2_has_aux = e2->flags.has_aux;
+    int value;
+
+    e1->flags.has_aux = e2->flags.has_aux = 0;
+    value = memcmp (&e1->flags, &e2->flags, sizeof (e1->flags));
+    e1->flags.has_aux = e1_has_aux;
+    e2->flags.has_aux = e2_has_aux;
+    if (value)
+      return 0;
+  }
+
+  /* compare the random elements of the plists. */
+  return (!plists_differ (extent_no_chase_plist (e1),
+			  extent_no_chase_plist (e2),
+			  0, 0, depth + 1));
+}
+
+static int
+extent_equal (Lisp_Object o1, Lisp_Object o2, int depth)
+{
+  struct extent *e1 = XEXTENT (o1);
+  struct extent *e2 = XEXTENT (o2);
+  return
+    (extent_start (e1) == extent_start (e2) &&
+     extent_end (e1) == extent_end (e2) &&
+     internal_equal (extent_object (e1), extent_object (e2), depth + 1) &&
+     properties_equal (extent_ancestor (e1), extent_ancestor (e2),
+		       depth));
+}
+
+static unsigned long
+extent_hash (Lisp_Object obj, int depth)
+{
+  struct extent *e = XEXTENT (obj);
+  /* No need to hash all of the elements; that would take too long.
+     Just hash the most common ones. */
+  return HASH3 (extent_start (e), extent_end (e),
+		internal_hash (extent_object (e), depth + 1));
+}
+
+static Lisp_Object
+extent_getprop (Lisp_Object obj, Lisp_Object prop)
+{
+  return Fextent_property (obj, prop, Qunbound);
+}
+
+static int
+extent_putprop (Lisp_Object obj, Lisp_Object prop, Lisp_Object value)
+{
+  error ("Not yet implemented"); /* #### */
+  return 0;
+}
+
+static int
+extent_remprop (Lisp_Object obj, Lisp_Object prop)
+{
+  error ("Not yet implemented"); /* #### */
+  return 0;
+}
+
+static Lisp_Object
+extent_plist (Lisp_Object obj)
+{
+  return Fextent_properties (obj);
+}
+
+
+/************************************************************************/
+/*			basic extent accessors				*/
+/************************************************************************/
+
+/* These functions are for checking externally-passed extent objects
+   and returning an extent's basic properties, which include the
+   buffer the extent is associated with, the endpoints of the extent's
+   range, the open/closed-ness of those endpoints, and whether the
+   extent is detached.  Manipulating these properties requires
+   manipulating the ordered lists that hold extents; thus, functions
+   to do that are in a later section. */
+
+/* Given a Lisp_Object that is supposed to be an extent, make sure it
+   is OK and return an extent pointer.  Extents can be in one of four
+   states:
+
+   1) destroyed
+   2) detached and not associated with a buffer
+   3) detached and associated with a buffer
+   4) attached to a buffer
+
+   If FLAGS is 0, types 2-4 are allowed.  If FLAGS is DE_MUST_HAVE_BUFFER,
+   types 3-4 are allowed.  If FLAGS is DE_MUST_BE_ATTACHED, only type 4
+   is allowed.
+   */
+
+static EXTENT
+decode_extent (Lisp_Object extent_obj, unsigned int flags)
+{
+  EXTENT extent;
+  Lisp_Object obj;
+
+  CHECK_LIVE_EXTENT (extent_obj);
+  extent = XEXTENT (extent_obj);
+  obj = extent_object (extent);
+
+  /* the following condition will fail if we're dealing with a freed extent */
+  assert (NILP (obj) || BUFFERP (obj) || STRINGP (obj));
+
+  if (flags & DE_MUST_BE_ATTACHED)
+    flags |= DE_MUST_HAVE_BUFFER;
+
+  /* if buffer is dead, then convert extent to have no buffer. */
+  if (BUFFERP (obj) && !BUFFER_LIVE_P (XBUFFER (obj)))
+    obj = extent_object (extent) = Qnil;
+
+  assert (!NILP (obj) || extent_detached_p (extent));
+
+  if (NILP (obj) && (flags & DE_MUST_HAVE_BUFFER))
+    {
+      signal_simple_error ("extent doesn't belong to a buffer or string",
+			   extent_obj);
+    }
+  
+  if (extent_detached_p (extent) && (flags & DE_MUST_BE_ATTACHED))
+    {
+      signal_simple_error ("extent cannot be detached", extent_obj);
+    }
+
+  return extent;
+}
+
+/* Note that the returned value is a buffer position, not a byte index. */
+
+static Lisp_Object
+extent_endpoint_external (Lisp_Object extent_obj, int endp)
+{
+  EXTENT extent = decode_extent (extent_obj, 0);
+
+  if (extent_detached_p (extent))
+    return Qnil;
+  else
+    return make_int (extent_endpoint_bufpos (extent, endp));
+}
+
+DEFUN ("extentp", Fextentp, Sextentp, 1, 1, 0 /*
+T if OBJECT is an extent.
+*/ )
+  (object)
+     Lisp_Object object;
+{
+  if (EXTENTP (object))
+    return Qt;
+  return Qnil;
+}
+ 
+DEFUN ("extent-live-p", Fextent_live_p, Sextent_live_p, 1, 1, 0 /*
+T if OBJECT is an extent and the extent has not been destroyed.
+*/ )
+  (object)
+     Lisp_Object object;
+{
+  if (EXTENTP (object) && EXTENT_LIVE_P (XEXTENT (object)))
+    return Qt;
+  return Qnil;
+}
+
+DEFUN ("extent-detached-p", Fextent_detached_p, Sextent_detached_p, 1, 1, 0 /*
+T if EXTENT is detached.
+*/ )
+  (extent)
+     Lisp_Object extent;
+{
+  if (extent_detached_p (decode_extent (extent, 0)))
+    return Qt;
+  return Qnil;
+}
+
+DEFUN ("extent-object", Fextent_object, Sextent_object, 1, 1, 0 /*
+Return object (buffer or string) EXTENT refers to.
+*/ )
+     (extent)
+     Lisp_Object extent;
+{
+  return extent_object (decode_extent (extent, 0));
+}
+
+DEFUN ("extent-start-position", Fextent_start_position, 
+       Sextent_start_position, 1, 1, 0 /*
+Return start position of EXTENT, or nil if EXTENT is detached.
+*/ )
+     (extent)
+     Lisp_Object extent;
+{
+  return extent_endpoint_external (extent, 0);
+}
+
+DEFUN ("extent-end-position", Fextent_end_position, 
+       Sextent_end_position, 1, 1, 0 /*
+Return end position of EXTENT, or nil if EXTENT is detached.
+*/ )
+     (extent)
+     Lisp_Object extent;
+{
+  return extent_endpoint_external (extent, 1);
+}
+
+DEFUN ("extent-length", Fextent_length, Sextent_length, 1, 1, 0 /*
+Return length of EXTENT in characters.
+*/ )
+     (extent)
+     Lisp_Object extent;
+{
+  EXTENT e = decode_extent (extent, DE_MUST_BE_ATTACHED);
+  return make_int (extent_endpoint_bufpos (e, 1)
+		   - extent_endpoint_bufpos (e, 0));
+}
+
+DEFUN ("next-extent", Fnext_extent, Snext_extent, 1, 1, 0 /*
+Find next extent after EXTENT.
+If EXTENT is a buffer return the first extent in the buffer; likewise
+ for strings.
+Extents in a buffer are ordered in what is called the \"display\"
+ order, which sorts by increasing start positions and then by *decreasing*
+ end positions.
+If you want to perform an operation on a series of extents, use
+ `map-extents' instead of this function; it is much more efficient.
+ The primary use of this function should be to enumerate all the
+ extents in a buffer.
+Note: The display order is not necessarily the order that `map-extents'
+ processes extents in!
+*/ )
+  (extent)
+   Lisp_Object extent;
+{
+  Lisp_Object val;
+  EXTENT next;
+
+  if (EXTENTP (extent))
+    next = extent_next (decode_extent (extent, DE_MUST_BE_ATTACHED));
+  else
+    next = extent_first (decode_buffer_or_string (extent));
+
+  if (!next)
+    return (Qnil);
+  XSETEXTENT (val, next);
+  return (val);
+}
+
+DEFUN ("previous-extent", Fprevious_extent, Sprevious_extent, 1, 1, 0 /*
+Find last extent before EXTENT.
+If EXTENT is a buffer return the last extent in the buffer; likewise
+ for strings.
+This function is analogous to `next-extent'.
+*/ )
+  (extent)
+   Lisp_Object extent;
+{
+  Lisp_Object val;
+  EXTENT prev;
+
+  if (EXTENTP (extent))
+    prev = extent_previous (decode_extent (extent, DE_MUST_BE_ATTACHED));
+  else
+    prev = extent_last (decode_buffer_or_string (extent));
+
+  if (!prev)
+    return (Qnil);
+  XSETEXTENT (val, prev);
+  return (val);
+}
+
+#ifdef DEBUG_XEMACS
+
+DEFUN ("next-e-extent", Fnext_e_extent, Snext_e_extent, 1, 1, 0 /*
+Find next extent after EXTENT using the \"e\" order.
+If EXTENT is a buffer return the first extent in the buffer; likewise
+ for strings.
+*/ )
+  (extent)
+   Lisp_Object extent;
+{
+  Lisp_Object val;
+  EXTENT next;
+
+  if (EXTENTP (extent))
+    next = extent_e_next (decode_extent (extent, DE_MUST_BE_ATTACHED));
+  else
+    next = extent_e_first (decode_buffer_or_string (extent));
+
+  if (!next)
+    return (Qnil);
+  XSETEXTENT (val, next);
+  return (val);
+}
+
+DEFUN ("previous-e-extent", Fprevious_e_extent, Sprevious_e_extent, 1, 1, 0 /*
+Find last extent before EXTENT using the \"e\" order.
+If EXTENT is a buffer return the last extent in the buffer; likewise
+ for strings.
+This function is analogous to `next-e-extent'.
+*/ )
+  (extent)
+   Lisp_Object extent;
+{
+  Lisp_Object val;
+  EXTENT prev;
+
+  if (EXTENTP (extent))
+    prev = extent_e_previous (decode_extent (extent, DE_MUST_BE_ATTACHED));
+  else
+    prev = extent_e_last (decode_buffer_or_string (extent));
+
+  if (!prev)
+    return (Qnil);
+  XSETEXTENT (val, prev);
+  return (val);
+}
+
+#endif
+
+DEFUN ("next-extent-change", Fnext_extent_change, Snext_extent_change,
+       1, 2, 0 /*
+Return the next position after POS where an extent begins or ends.
+If POS is at the end of the buffer or string, POS will be returned;
+ otherwise a position greater than POS will always be returned.
+If BUFFER is nil, the current buffer is assumed.
+*/ )
+  (pos, object)
+     Lisp_Object pos, object;
+{
+  Lisp_Object obj = decode_buffer_or_string (object);
+  Bytind bpos;
+
+  bpos = get_buffer_or_string_pos_byte (obj, pos, GB_ALLOW_PAST_ACCESSIBLE);
+  bpos = extent_find_end_of_run (obj, bpos, 1);
+  return make_int (buffer_or_string_bytind_to_bufpos (obj, bpos));
+}
+
+DEFUN ("previous-extent-change", Fprevious_extent_change,
+       Sprevious_extent_change, 1, 2, 0 /*
+Return the last position before POS where an extent begins or ends.
+If POS is at the beginning of the buffer or string, POS will be returned;
+ otherwise a position less than POS will always be returned.
+If OBJECT is nil, the current buffer is assumed.
+*/ )
+  (pos, object)
+     Lisp_Object pos, object;
+{
+  Lisp_Object obj = decode_buffer_or_string (object);
+  Bytind bpos;
+
+  bpos = get_buffer_or_string_pos_byte (obj, pos, GB_ALLOW_PAST_ACCESSIBLE);
+  bpos = extent_find_beginning_of_run (obj, bpos, 1);
+  return make_int (buffer_or_string_bytind_to_bufpos (obj, bpos));
+}
+
+
+/************************************************************************/
+/*		    	parent and children stuff			*/
+/************************************************************************/
+
+DEFUN ("extent-parent", Fextent_parent, Sextent_parent, 1, 1, 0 /*
+Return the parent (if any) of EXTENT.
+If an extent has a parent, it derives all its properties from that extent
+and has no properties of its own. (The only \"properties\" that the
+extent keeps are the buffer/string it refers to and the start and end
+points.) It is possible for an extent's parent to itself have a parent.
+*/ )
+     (extent)
+     Lisp_Object extent;
+/* do I win the prize for the strangest split infinitive? */
+{
+  EXTENT e = decode_extent (extent, 0);
+  return extent_parent (e);
+}
+
+DEFUN ("extent-children", Fextent_children, Sextent_children, 1, 1, 0 /*
+Return a list of the children (if any) of EXTENT.
+The children of an extent are all those extents whose parent is that extent.
+This function does not recursively trace children of children.
+\(To do that, use `extent-descendants'.)
+*/ )
+     (extent)
+     Lisp_Object extent;
+{
+  EXTENT e = decode_extent (extent, 0);
+  Lisp_Object children = extent_children (e);
+
+  if (!NILP (children))
+    return Fcopy_sequence (XWEAK_LIST_LIST (children));
+  else
+    return Qnil;
+}
+
+static void
+remove_extent_from_children_list (EXTENT e, Lisp_Object child)
+{
+  Lisp_Object children = extent_children (e);
+
+#ifdef ERROR_CHECK_EXTENTS
+  assert (!NILP (memq_no_quit (child, XWEAK_LIST_LIST (children))));
+#endif
+  XWEAK_LIST_LIST (children) =
+    delq_no_quit (child, XWEAK_LIST_LIST (children));
+}
+
+static void
+add_extent_to_children_list (EXTENT e, Lisp_Object child)
+{
+  Lisp_Object children = extent_children (e);
+
+  if (NILP (children))
+    {
+      children = make_weak_list (WEAK_LIST_SIMPLE);
+      set_extent_no_chase_aux_field (e, children, children);
+    }
+
+#ifdef ERROR_CHECK_EXTENTS
+  assert (NILP (memq_no_quit (child, XWEAK_LIST_LIST (children))));
+#endif
+  XWEAK_LIST_LIST (children) = Fcons (child, XWEAK_LIST_LIST (children));
+}
+
+DEFUN ("set-extent-parent", Fset_extent_parent, Sset_extent_parent, 2, 2, 0 /*
+Set the parent of EXTENT to PARENT (may be nil).
+See `extent-parent'.
+*/ )
+     (extent, parent)
+     Lisp_Object extent, parent;
+{
+  EXTENT e = decode_extent (extent, 0);
+  Lisp_Object cur_parent = extent_parent (e);
+  Lisp_Object rest;
+
+  XSETEXTENT (extent, e);
+  if (!NILP (parent))
+    CHECK_LIVE_EXTENT (parent);
+  if (EQ (parent, cur_parent))
+    return Qnil;
+  for (rest = parent; !NILP (rest); rest = extent_parent (XEXTENT (rest)))
+    if (EQ (rest, extent))
+      signal_simple_error ("Circular parent chain would result", extent);
+  if (NILP (parent))
+    {
+      remove_extent_from_children_list (XEXTENT (cur_parent), extent);
+      set_extent_no_chase_aux_field (e, parent, Qnil);
+      e->flags.has_parent = 0;
+    }
+  else
+    {
+      add_extent_to_children_list (XEXTENT (parent), extent);
+      set_extent_no_chase_aux_field (e, parent, parent);
+      e->flags.has_parent = 1;
+    }
+  /* changing the parent also changes the properties of all children. */
+  extent_maybe_changed_for_redisplay (e, 1);
+  return Qnil;
+}
+
+
+/************************************************************************/
+/*		    	basic extent mutators				*/
+/************************************************************************/
+
+/* Note:  If you track non-duplicable extents by undo, you'll get bogus
+   undo records for transient extents via update-extent.
+   For example, query-replace will do this.
+ */
+
+static void
+set_extent_endpoints_1 (EXTENT extent, Memind start, Memind end)
+{
+#ifdef ERROR_CHECK_EXTENTS
+  Lisp_Object obj = extent_object (extent);
+
+  assert (start <= end);
+  if (BUFFERP (obj))
+    {
+      assert (valid_memind_p (XBUFFER (obj), start));
+      assert (valid_memind_p (XBUFFER (obj), end));
+    }
+#endif
+
+  /* Optimization: if the extent is already where we want it to be,
+     do nothing. */
+  if (!extent_detached_p (extent) && extent_start (extent) == start &&
+      extent_end (extent) == end)
+    return;
+
+  if (extent_detached_p (extent))
+    {
+      if (extent_duplicable_p (extent))
+	{
+	  Lisp_Object extent_obj;
+	  XSETEXTENT (extent_obj, extent);
+	  record_extent (extent_obj, 1);
+	}
+    }
+  else
+    extent_detach (extent);
+
+  set_extent_start (extent, start);
+  set_extent_end (extent, end);
+  extent_attach (extent);
+}
+
+/* Set extent's endpoints to S and E, and put extent in buffer or string
+   OBJECT. (If OBJECT is nil, do not change the extent's object.) */
+
+void
+set_extent_endpoints (EXTENT extent, Bytind s, Bytind e, Lisp_Object object)
+{
+  Memind start, end;
+
+  if (NILP (object))
+    {
+      object = extent_object (extent);
+      assert (!NILP (object));
+    }
+  else if (!EQ (object, extent_object (extent)))
+    {
+      extent_detach (extent);
+      extent_object (extent) = object;
+    }
+
+  start = s < 0 ? extent_start (extent) :
+    buffer_or_string_bytind_to_memind (object, s);
+  end = e < 0 ? extent_end (extent) :
+    buffer_or_string_bytind_to_memind (object, e);
+  set_extent_endpoints_1 (extent, start, end);
+}
+
+static void
+set_extent_openness (EXTENT extent, int start_open, int end_open)
+{
+  if (start_open == -1)
+    start_open = extent_start_open_p (extent);
+  if (end_open == -1)
+    end_open = extent_end_open_p (extent);
+  extent_start_open_p (extent) = start_open;
+  extent_end_open_p (extent) = end_open;
+  /* changing the open/closedness of an extent does not affect
+     redisplay. */
+}
+
+static EXTENT
+make_extent_internal (Lisp_Object object, Bytind from, Bytind to)
+{
+  EXTENT extent;
+  
+  extent = make_extent_detached (object);
+  set_extent_endpoints (extent, from, to, Qnil);
+  return extent;
+}
+
+static EXTENT
+copy_extent (EXTENT original, Bytind from, Bytind to, Lisp_Object object)
+{
+  EXTENT e;
+
+  e = make_extent_detached (object);
+  if (from >= 0)
+    set_extent_endpoints (e, from, to, Qnil);
+
+  e->plist = Fcopy_sequence (original->plist);
+  memcpy (&e->flags, &original->flags, sizeof (e->flags));
+  if (e->flags.has_aux)
+    {
+      /* also need to copy the aux struct.  It won't work for
+	 this extent to share the same aux struct as the original
+	 one. */
+      struct extent_auxiliary *data =
+	alloc_lcrecord (sizeof (struct extent_auxiliary),
+			lrecord_extent_auxiliary);
+
+      copy_lcrecord (data, XEXTENT_AUXILIARY (XCAR (original->plist)));
+      XSETEXTENT_AUXILIARY (XCAR (e->plist), data);
+    }
+
+  {
+    /* we may have just added another child to the parent extent. */
+    Lisp_Object parent = extent_parent (e);
+    if (!NILP (parent))
+      {
+	Lisp_Object extent;
+	XSETEXTENT (extent, e);
+	add_extent_to_children_list (XEXTENT (parent), extent);
+      }
+  }
+      
+  /* #### it's still unclear to me that this Energize-specific junk
+     needs to be in here.  Just use the general mechanisms, or fix
+     them up! --ben */
+#ifdef ENERGIZE
+  if (energize_extent_data (original))
+    {
+      extent_plist_slot (e) = Qnil; /* slightly antisocial... */
+      restore_energize_extent_state (e);
+    }
+#endif
+
+  return e;
+}
+
+static void 
+destroy_extent (EXTENT extent) 
+{
+  Lisp_Object rest, nextrest, children;
+  Lisp_Object extent_obj = Qnil;
+
+  if (!extent_detached_p (extent))
+    extent_detach (extent);
+  /* disassociate the extent from its children and parent */
+  children = extent_children (extent);
+  if (!NILP (children))
+    {
+      LIST_LOOP_DELETING (rest, nextrest, XWEAK_LIST_LIST (children))
+	Fset_extent_parent (XCAR (rest), Qnil);
+    }
+  XSETEXTENT (extent_obj, extent);
+  Fset_extent_parent (extent_obj, Qnil);
+  /* mark the extent as destroyed */
+  extent_object (extent) = Qt;
+}
+
+DEFUN ("make-extent", Fmake_extent, Smake_extent, 2, 3, 0 /*
+Make an extent for the range [FROM, TO) in BUFFER-OR-STRING.
+BUFFER-OR-STRING defaults to the current buffer.  Insertions at point
+TO will be outside of the extent; insertions at FROM will be inside the
+extent, causing the extent to grow. (This is the same way that markers
+behave.) You can change the behavior of insertions at the endpoints
+using `set-extent-property'.  The extent is initially detached if both
+FROM and TO are nil, and in this case BUFFER-OR-STRING defaults to nil,
+meaning the extent is in no buffer and no string.
+*/ )
+  (from, to, buffer_or_string)
+   Lisp_Object from, to, buffer_or_string;
+{
+  Lisp_Object extent_obj = Qnil;
+  Lisp_Object obj;
+
+  obj = decode_buffer_or_string (buffer_or_string);
+  if (NILP (from) && NILP (to))
+    {
+      if (NILP (buffer_or_string))
+	obj = Qnil;
+      XSETEXTENT (extent_obj, make_extent_detached (obj));
+    }
+  else
+    {
+      Bytind start, end;
+
+      get_buffer_or_string_range_byte (obj, from, to, &start, &end,
+				       GB_ALLOW_PAST_ACCESSIBLE);
+      XSETEXTENT (extent_obj, make_extent_internal (obj, start, end));
+    }
+  return extent_obj;
+}
+
+DEFUN ("copy-extent", Fcopy_extent, Scopy_extent, 1, 2, 0 /*
+Make a copy of EXTENT.  It is initially detached.
+Optional argument BUFFER-OR-STRING defaults to EXTENT's buffer or string.
+*/ )
+  (extent, buffer_or_string)
+   Lisp_Object extent, buffer_or_string;
+{
+  EXTENT ext = decode_extent (extent, 0);
+
+  if (NILP (buffer_or_string))
+    buffer_or_string = extent_object (ext);
+  else
+    buffer_or_string = decode_buffer_or_string (buffer_or_string);
+
+  XSETEXTENT (extent, copy_extent (ext, -1, -1, buffer_or_string));
+  return extent;
+}
+
+DEFUN ("delete-extent", Fdelete_extent, Sdelete_extent, 1, 1, 0 /*
+Remove EXTENT from its buffer and destroy it.
+This does not modify the buffer's text, only its display properties.
+The extent cannot be used thereafter.
+*/ )
+  (extent)
+   Lisp_Object extent;
+{
+  EXTENT ext;
+
+  /* We do not call decode_extent() here because already-destroyed
+     extents are OK. */
+  CHECK_EXTENT (extent);
+  ext = XEXTENT (extent);
+
+  if (!EXTENT_LIVE_P (ext))
+    return Qnil;
+  destroy_extent (ext);
+  return Qnil;
+}
+
+DEFUN ("detach-extent", Fdetach_extent, Sdetach_extent, 1, 1, 0 /*
+Remove EXTENT from its buffer in such a way that it can be re-inserted.
+An extent is also detached when all of its characters are all killed by a
+deletion, unless its `detachable' property has been unset.
+
+Extents which have the `duplicable' attribute are tracked by the undo
+mechanism.  Detachment via `detach-extent' and string deletion is recorded,
+as is attachment via `insert-extent' and string insertion.  Extent motion,
+face changes, and attachment via `make-extent' and `set-extent-endpoints'
+are not recorded.  This means that extent changes which are to be undo-able
+must be performed by character editing, or by insertion and detachment of
+duplicable extents.
+*/ )
+  (extent)
+   Lisp_Object extent;
+{
+  EXTENT ext = decode_extent (extent, 0);
+
+  if (extent_detached_p (ext))
+    return extent;
+  if (extent_duplicable_p (ext))
+    record_extent (extent, 0);
+  extent_detach (ext);
+
+  return extent;
+}
+
+DEFUN ("set-extent-endpoints", Fset_extent_endpoints, Sset_extent_endpoints,
+       3, 4, 0 /*
+Set the endpoints of EXTENT to START, END.
+If START and END are null, call detach-extent on EXTENT.
+BUFFER-OR-STRING specifies the new buffer or string that the extent should
+be in, and defaults to EXTENT's buffer or string. (If nil, and EXTENT
+is in no buffer and no string, it defaults to the current buffer.)
+See documentation on `detach-extent' for a discussion of undo recording.
+*/ )
+  (extent, start, end, buffer_or_string)
+   Lisp_Object extent, start, end, buffer_or_string;
+{
+  EXTENT ext;
+  Bytind s, e;
+
+  ext = decode_extent (extent, 0);
+
+  if (NILP (buffer_or_string))
+    {
+      buffer_or_string = extent_object (ext);
+      if (NILP (buffer_or_string))
+	buffer_or_string = Fcurrent_buffer ();
+    }
+  else
+    buffer_or_string = decode_buffer_or_string (buffer_or_string);
+
+  if (NILP (start) && NILP (end))
+    return Fdetach_extent (extent);
+      
+  get_buffer_or_string_range_byte (buffer_or_string, start, end, &s, &e,
+				   GB_ALLOW_PAST_ACCESSIBLE);
+
+  set_extent_endpoints (ext, s, e, buffer_or_string);
+  return extent;
+}
+
+
+/************************************************************************/
+/*		           mapping over extents				*/
+/************************************************************************/
+
+static unsigned int
+decode_map_extents_flags (Lisp_Object flags)
+{
+  unsigned int retval = 0;
+  unsigned int all_extents_specified = 0;
+  unsigned int in_region_specified = 0;
+
+  if (EQ (flags, Qt)) /* obsoleteness compatibility */
+    return ME_END_CLOSED;
+  if (NILP (flags))
+    return 0;
+  if (SYMBOLP (flags))
+    flags = Fcons (flags, Qnil);
+  while (!NILP (flags))
+    {
+      Lisp_Object sym;
+      CHECK_CONS (flags);
+      sym = XCAR (flags);
+      CHECK_SYMBOL (sym);
+      if (EQ (sym, Qall_extents_closed) || EQ (sym, Qall_extents_open) ||
+	  EQ (sym, Qall_extents_closed_open) ||
+	  EQ (sym, Qall_extents_open_closed))
+	{
+	  if (all_extents_specified)
+	    error ("Only one `all-extents-*' flag may be specified");
+	  all_extents_specified = 1;
+	}
+      if (EQ (sym, Qstart_in_region) || EQ (sym, Qend_in_region) ||
+	  EQ (sym, Qstart_and_end_in_region) ||
+	  EQ (sym, Qstart_or_end_in_region))
+	{
+	  if (in_region_specified)
+	    error ("Only one `*-in-region' flag may be specified");
+	  in_region_specified = 1;
+	}
+
+      /* I do so love that conditional operator ... */
+      retval |=
+	EQ (sym, Qend_closed) ? ME_END_CLOSED :
+	EQ (sym, Qstart_open) ? ME_START_OPEN :
+	EQ (sym, Qall_extents_closed) ? ME_ALL_EXTENTS_CLOSED :
+	EQ (sym, Qall_extents_open) ? ME_ALL_EXTENTS_OPEN :
+	EQ (sym, Qall_extents_closed_open) ? ME_ALL_EXTENTS_CLOSED_OPEN :
+	EQ (sym, Qall_extents_open_closed) ? ME_ALL_EXTENTS_OPEN_CLOSED :
+	EQ (sym, Qstart_in_region) ? ME_START_IN_REGION :
+	EQ (sym, Qend_in_region) ? ME_END_IN_REGION :
+	EQ (sym, Qstart_and_end_in_region) ? ME_START_AND_END_IN_REGION :
+	EQ (sym, Qstart_or_end_in_region) ? ME_START_OR_END_IN_REGION :
+	EQ (sym, Qnegate_in_region) ? ME_NEGATE_IN_REGION :
+	(signal_simple_error ("Invalid `map-extents' flag", sym), 0);
+
+      flags = XCDR (flags);
+    }
+  return retval;
+}
+
+DEFUN ("extent-in-region-p", Fextent_in_region_p, Sextent_in_region_p,
+       1, 4, 0 /*
+Return whether EXTENT overlaps a specified region.
+This is equivalent to whether `map-extents' would visit EXTENT when called
+with these args.
+*/ )
+     (extent, from, to, flags)
+     Lisp_Object extent, from, to, flags;
+{
+  EXTENT ext;
+  Lisp_Object obj;
+  Bytind start, end;
+
+  ext = decode_extent (extent, DE_MUST_BE_ATTACHED);
+  obj = extent_object (ext);
+  get_buffer_or_string_range_byte (obj, from, to, &start, &end, GB_ALLOW_NIL |
+				   GB_ALLOW_PAST_ACCESSIBLE);
+
+  if (extent_in_region_p (ext, start, end, decode_map_extents_flags (flags)))
+    return Qt;
+  return Qnil;
+}
+
+struct slow_map_extents_arg
+{
+  Lisp_Object map_arg;
+  Lisp_Object map_routine;
+  Lisp_Object result;
+  Lisp_Object property;
+  Lisp_Object value;
+};
+
+static int
+slow_map_extents_function (EXTENT extent, void *arg)
+{
+  /* This function can GC */
+  struct slow_map_extents_arg *closure = (struct slow_map_extents_arg *) arg;
+  Lisp_Object extent_obj;
+
+  XSETEXTENT (extent_obj, extent);
+
+  /* make sure this extent qualifies according to the PROPERTY
+     and VALUE args */
+
+  if (!NILP (closure->property))
+    {
+      Lisp_Object value = Fextent_property (extent_obj, closure->property,
+					    Qnil);
+      if ((NILP (closure->value) && NILP (value)) ||
+	  (!NILP (closure->value) && !EQ (value, closure->value)))
+	return 0;
+    }
+
+  closure->result = call2 (closure->map_routine, extent_obj,
+			   closure->map_arg);
+  if (NILP (closure->result))
+    return 0;
+  else
+    return 1;
+}
+
+DEFUN ("map-extents", Fmap_extents, Smap_extents, 1, 8, 0 /*
+Map FUNCTION over the extents which overlap a region in OBJECT.
+OBJECT is normally a buffer or string but could be an extent (see below).
+The region is normally bounded by [FROM, TO) (i.e. the beginning of the
+region is closed and the end of the region is open), but this can be
+changed with the FLAGS argument (see below for a complete discussion).
+
+FUNCTION is called with the arguments (extent, MAPARG).  The arguments
+OBJECT, FROM, TO, MAPARG, and FLAGS are all optional and default to
+the current buffer, the beginning of OBJECT, the end of OBJECT, nil,
+and nil, respectively.  `map-extents' returns the first non-nil result
+produced by FUNCTION, and no more calls to FUNCTION are made after it
+returns non-nil.
+
+If OBJECT is an extent, FROM and TO default to the extent's endpoints,
+and the mapping omits that extent and its predecessors.  This feature
+supports restarting a loop based on `map-extents'.  Note: OBJECT must
+be attached to a buffer or string, and the mapping is done over that
+buffer or string.
+
+An extent overlaps the region if there is any point in the extent that is
+also in the region. (For the purpose of overlap, zero-length extents and
+regions are treated as closed on both ends regardless of their endpoints'
+specified open/closedness.) Note that the endpoints of an extent or region
+are considered to be in that extent or region if and only if the
+corresponding end is closed.  For example, the extent [5,7] overlaps the
+region [2,5] because 5 is in both the extent and the region.  However, (5,7]
+does not overlap [2,5] because 5 is not in the extent, and neither [5,7] nor
+\(5,7] overlaps the region [2,5) because 5 is not in the region.
+
+The optional FLAGS can be a symbol or a list of one or more symbols,
+modifying the behavior of `map-extents'.  Allowed symbols are:
+
+end-closed		The region's end is closed.
+
+start-open		The region's start is open.
+
+all-extents-closed	Treat all extents as closed on both ends for the
+			purpose of determining whether they overlap the
+			region, irrespective of their actual open- or
+			closedness.
+all-extents-open	Treat all extents as open on both ends.
+all-extents-closed-open	Treat all extents as start-closed, end-open.
+all-extents-open-closed	Treat all extents as start-open, end-closed.
+
+start-in-region		In addition to the above conditions for extent
+			overlap, the extent's start position must lie within
+			the specified region.  Note that, for this
+			condition, open start positions are treated as if
+			0.5 was added to the endpoint's value, and open
+			end positions are treated as if 0.5 was subtracted
+			from the endpoint's value.
+end-in-region		The extent's end position must lie within the
+			region.
+start-and-end-in-region	Both the extent's start and end positions must lie
+			within the region.
+start-or-end-in-region	Either the extent's start or end position must lie
+			within the region.
+
+negate-in-region	The condition specified by a `*-in-region' flag
+			must NOT hold for the extent to be considered.
+
+
+At most one of `all-extents-closed', `all-extents-open',
+`all-extents-closed-open', and `all-extents-open-closed' may be specified.
+
+At most one of `start-in-region', `end-in-region',
+`start-and-end-in-region', and `start-or-end-in-region' may be specified.
+
+If optional arg PROPERTY is non-nil, only extents with that property set
+on them will be visited.  If optional arg VALUE is non-nil, only extents
+whose value for that property is `eq' to VALUE will be visited.
+*/ )
+  (function, object, from, to, maparg, flags, property, value)
+  Lisp_Object function, object, from, to, maparg, flags, property, value;
+{
+  /* This function can GC */
+  struct slow_map_extents_arg closure;
+  unsigned int me_flags;
+  Bytind start, end;
+  struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5;
+  EXTENT after = 0;
+
+  if (EXTENTP (object))
+    {
+      after = decode_extent (object, DE_MUST_BE_ATTACHED);
+      if (NILP (from))
+	from = Fextent_start_position (object);
+      if (NILP (to))
+	to = Fextent_end_position (object);
+      object = extent_object (after);
+    }
+  else
+    object = decode_buffer_or_string (object);
+
+  get_buffer_or_string_range_byte (object, from, to, &start, &end,
+				   GB_ALLOW_NIL | GB_ALLOW_PAST_ACCESSIBLE);
+
+  me_flags = decode_map_extents_flags (flags);
+
+  if (!NILP (property))
+    {
+      CHECK_SYMBOL (property);
+      if (!NILP (value))
+	value =	canonicalize_extent_property (property, value);
+    }
+
+  GCPRO5 (function, maparg, object, property, value);
+
+  closure.map_arg = maparg;
+  closure.map_routine = function;
+  closure.result = Qnil;
+  closure.property = property;
+  closure.value = value;
+
+  map_extents_bytind (start, end, slow_map_extents_function,
+		      (void *) &closure, object, after,
+		      /* You never know what the user might do ... */
+		      me_flags | ME_MIGHT_CALL_ELISP);
+
+  UNGCPRO;
+  return closure.result;
+}
+
+
+/************************************************************************/
+/*		mapping over extents -- other functions			*/
+/************************************************************************/
+
+/* ------------------------------- */
+/*      map-extent-children        */
+/* ------------------------------- */
+
+struct slow_map_extent_children_arg
+{
+  Lisp_Object map_arg;
+  Lisp_Object map_routine;
+  Lisp_Object result;
+  Lisp_Object property;
+  Lisp_Object value;
+  Bytind start_min;
+  Bytind prev_start;
+  Bytind prev_end;
+};
+
+static int
+slow_map_extent_children_function (EXTENT extent, void *arg)
+{
+  /* This function can GC */
+  struct slow_map_extent_children_arg *closure =
+    (struct slow_map_extent_children_arg *) arg;
+  Lisp_Object extent_obj;
+  Bytind start = extent_endpoint_bytind (extent, 0);
+  Bytind end = extent_endpoint_bytind (extent, 1);
+  /* Make sure the extent starts inside the region of interest,
+     rather than just overlaps it.
+     */
+  if (start < closure->start_min)
+    return 0;
+  /* Make sure the extent is not a child of a previous visited one.
+     We know already, because of extent ordering,
+     that start >= prev_start, and that if
+     start == prev_start, then end <= prev_end.
+     */
+  if (start == closure->prev_start)
+    {
+      if (end < closure->prev_end)
+	return 0;
+    }
+  else /* start > prev_start */
+    {
+      if (start < closure->prev_end)
+	return 0;
+      /* corner case:  prev_end can be -1 if there is no prev */
+    }
+  XSETEXTENT (extent_obj, extent);
+
+  /* make sure this extent qualifies according to the PROPERTY
+     and VALUE args */
+
+  if (!NILP (closure->property))
+    {
+      Lisp_Object value = Fextent_property (extent_obj, closure->property,
+					    Qnil);
+      if ((NILP (closure->value) && NILP (value)) ||
+	  (!NILP (closure->value) && !EQ (value, closure->value)))
+	return 0;
+    }
+
+  closure->result = call2 (closure->map_routine, extent_obj,
+			   closure->map_arg);
+
+  /* Since the callback may change the buffer, compute all stored
+     buffer positions here.
+     */
+  closure->start_min = -1;	/* no need for this any more */
+  closure->prev_start = extent_endpoint_bytind (extent, 0);
+  closure->prev_end = extent_endpoint_bytind (extent, 1);
+
+  if (NILP (closure->result))
+    return 0;
+  else
+    return 1;
+}
+
+DEFUN ("map-extent-children", Fmap_extent_children, Smap_extent_children,
+       1, 8, 0 /*
+Map FUNCTION over the extents in the region from FROM to TO.
+FUNCTION is called with arguments (extent, MAPARG).  See `map-extents'
+for a full discussion of the arguments FROM, TO, and FLAGS.
+
+The arguments are the same as for `map-extents', but this function differs
+in that it only visits extents which start in the given region, and also
+in that, after visiting an extent E, it skips all other extents which start
+inside E but end before E's end.
+
+Thus, this function may be used to walk a tree of extents in a buffer:
+	(defun walk-extents (buffer &optional ignore)
+	 (map-extent-children 'walk-extents buffer))
+*/ )
+     (function, object, from, to, maparg, flags, property, value)
+     Lisp_Object function, object, from, to, maparg, flags, property, value;
+{
+  /* This function can GC */
+  struct slow_map_extent_children_arg closure;
+  unsigned int me_flags;
+  Bytind start, end;
+  struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5;
+  EXTENT after = 0;
+
+  if (EXTENTP (object))
+    {
+      after = decode_extent (object, DE_MUST_BE_ATTACHED);
+      if (NILP (from))
+	from = Fextent_start_position (object);
+      if (NILP (to))
+	to = Fextent_end_position (object);
+      object = extent_object (after);
+    }
+  else
+    object = decode_buffer_or_string (object);
+
+  get_buffer_or_string_range_byte (object, from, to, &start, &end,
+				   GB_ALLOW_NIL | GB_ALLOW_PAST_ACCESSIBLE);
+
+  me_flags = decode_map_extents_flags (flags);
+
+  if (!NILP (property))
+    {
+      CHECK_SYMBOL (property);
+      if (!NILP (value))
+	value =	canonicalize_extent_property (property, value);
+    }
+
+  GCPRO5 (function, maparg, object, property, value);
+
+  closure.map_arg = maparg;
+  closure.map_routine = function;
+  closure.result = Qnil;
+  closure.property = property;
+  closure.value = value;
+  closure.start_min = start;
+  closure.prev_start = -1;
+  closure.prev_end = -1;
+  map_extents_bytind (start, end, slow_map_extent_children_function,
+		      (void *) &closure, object, after,
+		      /* You never know what the user might do ... */
+		      me_flags | ME_MIGHT_CALL_ELISP);
+
+  UNGCPRO;
+  return closure.result;
+}
+
+/* ------------------------------- */
+/*             extent-at           */
+/* ------------------------------- */
+
+/* find "smallest" matching extent containing pos -- (flag == 0) means 
+   all extents match, else (EXTENT_FLAGS (extent) & flag) must be true;
+   for more than one matching extent with precisely the same endpoints,
+   we choose the last extent in the extents_list.
+   The search stops just before "before", if that is non-null.
+   */
+
+struct extent_at_arg
+{
+  EXTENT best_match;
+  Memind best_start;
+  Memind best_end;
+  Lisp_Object prop;
+  EXTENT before;
+};
+
+enum extent_at_flag
+{
+  EXTENT_AT_AFTER,
+  EXTENT_AT_BEFORE,
+  EXTENT_AT_AT
+};
+
+static enum extent_at_flag
+decode_extent_at_flag (Lisp_Object at_flag)
+{
+  enum extent_at_flag fl;
+
+  if (NILP (at_flag))
+    fl = EXTENT_AT_AFTER;
+  else
+    {
+      CHECK_SYMBOL (at_flag);
+      if (EQ (at_flag, Qafter))
+	fl = EXTENT_AT_AFTER;
+      else if (EQ (at_flag, Qbefore))
+	fl = EXTENT_AT_BEFORE;
+      else if (EQ (at_flag, Qat))
+	fl = EXTENT_AT_AT;
+      else
+	signal_simple_error ("Invalid AT-FLAG in `extent-at'", at_flag);
+    }
+
+  return fl;
+}
+
+static int
+extent_at_mapper (EXTENT e, void *arg)
+{
+  struct extent_at_arg *closure = (struct extent_at_arg *) arg;
+
+  if (e == closure->before)
+    return 1;
+
+  /* If closure->prop is non-nil, then the extent is only acceptable
+     if it has a non-nil value for that property. */
+  if (!NILP (closure->prop))
+    {
+      Lisp_Object extent;
+      XSETEXTENT (extent, e);
+      if (NILP (Fextent_property (extent, closure->prop, Qnil)))
+	return 0;
+    }
+
+    {
+      EXTENT current = closure->best_match;
+
+      if (!current)
+	goto accept;
+      /* redundant but quick test */
+      else if (extent_start (current) > extent_start (e))
+	return 0;
+
+      /* we return the "last" best fit, instead of the first --
+	 this is because then the glyph closest to two equivalent
+	 extents corresponds to the "extent-at" the text just past
+	 that same glyph */
+      else if (!EXTENT_LESS_VALS (e, closure->best_start,
+				  closure->best_end))
+        goto accept;
+      else
+	return 0;
+    accept:
+      closure->best_match = e;
+      closure->best_start = extent_start (e);
+      closure->best_end = extent_end (e);
+    }
+
+  return 0;
+}
+
+static Lisp_Object
+extent_at_bytind (Bytind position, Lisp_Object object, Lisp_Object property,
+		  EXTENT before, enum extent_at_flag at_flag)
+{
+  struct extent_at_arg closure;
+  Lisp_Object extent_obj = Qnil;
+
+  /* it might be argued that invalid positions should cause
+     errors, but the principle of least surprise dictates that
+     nil should be returned (extent-at is often used in
+     response to a mouse event, and in many cases previous events
+     have changed the buffer contents).
+
+     Also, the openness stuff in the text-property code currently
+     does not check its limits and might go off the end. */
+  if ((at_flag == EXTENT_AT_BEFORE
+       ? position <= buffer_or_string_absolute_begin_byte (object)
+       : position < buffer_or_string_absolute_begin_byte (object))
+      || (at_flag == EXTENT_AT_AFTER
+	  ? position >= buffer_or_string_absolute_end_byte (object)
+	  : position > buffer_or_string_absolute_end_byte (object)))
+    return Qnil;
+
+  closure.best_match = 0;
+  closure.prop = property;
+  closure.before = before;
+  
+  map_extents_bytind (at_flag == EXTENT_AT_BEFORE ? position - 1 : position,
+		      at_flag == EXTENT_AT_AFTER ? position + 1 : position,
+		      extent_at_mapper, (void *) &closure, object, 0,
+		      ME_START_OPEN | ME_ALL_EXTENTS_CLOSED);
+
+  if (!closure.best_match)
+    return Qnil;
+
+  XSETEXTENT (extent_obj, closure.best_match);
+  return extent_obj;
+}
+
+DEFUN ("extent-at", Fextent_at, Sextent_at, 1, 5, 0 /*
+Find \"smallest\" extent at POS in OBJECT having PROPERTY set.
+Normally, an extent is \"at\" POS if it overlaps the region (POS, POS+1);
+ i.e. if it covers the character after POS. (However, see the definition
+ of AT-FLAG.) \"Smallest\" means the extent that comes last in the display
+ order; this normally means the extent whose start position is closest to
+ POS.  See `next-extent' for more information.
+OBJECT specifies a buffer or string and defaults to the current buffer.
+PROPERTY defaults to nil, meaning that any extent will do.
+Properties are attached to extents with `set-extent-property', which see.
+Returns nil if POS is invalid or there is no matching extent at POS.
+If the fourth argument BEFORE is not nil, it must be an extent; any returned
+ extent will precede that extent.  This feature allows `extent-at' to be
+ used by a loop over extents.
+AT-FLAG controls how end cases are handled, and should be one of:
+
+nil or `after'		An extent is at POS if it covers the character
+			after POS.  This is consistent with the way
+			that text properties work.
+`before'		An extent is at POS if it covers the character
+			before POS.
+`at'			An extent is at POS if it overlaps or abuts POS.
+			This includes all zero-length extents at POS.
+
+Note that in all cases, the start-openness and end-openness of the extents
+considered is ignored.  If you want to pay attention to those properties,
+you should use `map-extents', which gives you more control.
+*/ )
+     (pos, object, property, before, at_flag)
+     Lisp_Object pos, object, property, before, at_flag;
+{
+  Bytind position;
+  EXTENT before_extent;
+  enum extent_at_flag fl;
+
+  object = decode_buffer_or_string (object);
+  position = get_buffer_or_string_pos_byte (object, pos, GB_NO_ERROR_IF_BAD);
+  CHECK_SYMBOL (property);
+  if (NILP (before))
+    before_extent = 0;
+  else
+    before_extent = decode_extent (before, DE_MUST_BE_ATTACHED);
+  if (before_extent && !EQ (object, extent_object (before_extent)))
+    signal_simple_error ("extent not in specified buffer or string", object);
+  fl = decode_extent_at_flag (at_flag);
+
+  return extent_at_bytind (position, object, property, before_extent, fl);
+}
+
+/* ------------------------------- */
+/*   verify_extent_modification()  */
+/* ------------------------------- */
+
+/* verify_extent_modification() is called when a buffer or string is
+   modified to check whether the modification is occuring inside a
+   read-only extent.
+ */
+
+struct verify_extents_arg
+{
+  Lisp_Object object;
+  Memind start;
+  Memind end;
+  Lisp_Object iro; /* value of inhibit-read-only */
+};
+
+static int
+verify_extent_mapper (EXTENT extent, void *arg)
+{
+  struct verify_extents_arg *closure = (struct verify_extents_arg *) arg;
+  Lisp_Object prop = extent_read_only (extent);
+
+  if (NILP (prop))
+    return 0;
+
+  if (CONSP (closure->iro) && !NILP (Fmemq (prop, closure->iro)))
+    return 0;
+
+  /* Allow deletion if the extent is completely contained in
+     the region being deleted.
+     This is important for supporting tokens which are internally
+     write-protected, but which can be killed and yanked as a whole.
+     Ignore open/closed distinctions at this point.
+     -- Rose
+     */
+  if (closure->start != closure->end &&
+      extent_start (extent) >= closure->start &&
+      extent_end (extent) <= closure->end)
+    return 0;
+
+  while (1)
+    Fsignal (Qbuffer_read_only, (list1 (closure->object)));
+
+  RETURN_NOT_REACHED(0)
+}
+
+/* Value of Vinhibit_read_only is precomputed and passed in for
+   efficiency */
+
+void
+verify_extent_modification (Lisp_Object object, Bytind from, Bytind to,
+			    Lisp_Object inhibit_read_only_value)
+{
+  int closed;
+  struct verify_extents_arg closure;
+
+  /* If insertion, visit closed-endpoint extents touching the insertion
+     point because the text would go inside those extents.  If deletion,
+     treat the range as open on both ends so that touching extents are not
+     visited.  Note that we assume that an insertion is occurring if the
+     changed range has zero length, and a deletion otherwise.  This
+     fails if a change (i.e. non-insertion, non-deletion) is happening.
+     As far as I know, this doesn't currently occur in XEmacs. --ben */
+  closed = (from==to);
+  closure.object = object;
+  closure.start = buffer_or_string_bytind_to_memind (object, from);
+  closure.end = buffer_or_string_bytind_to_memind (object, to);
+  closure.iro = inhibit_read_only_value;
+
+  map_extents_bytind (from, to, verify_extent_mapper, (void *) &closure,
+		      object, 0, closed ? ME_END_CLOSED : ME_START_OPEN);
+}
+
+/* ------------------------------------ */
+/*    process_extents_for_insertion()   */
+/* ------------------------------------ */
+
+struct process_extents_for_insertion_arg
+{
+  Bytind opoint;
+  int length;
+  Lisp_Object object;
+};
+   
+/*   A region of length LENGTH was just inserted at OPOINT.  Modify all
+     of the extents as required for the insertion, based on their
+     start-open/end-open properties.
+ */
+
+static int
+process_extents_for_insertion_mapper (EXTENT extent, void *arg)
+{
+  struct process_extents_for_insertion_arg *closure = 
+    (struct process_extents_for_insertion_arg *) arg;
+  Memind indecks = buffer_or_string_bytind_to_memind (closure->object,
+						      closure->opoint);
+
+  /* When this function is called, one end of the newly-inserted text should
+     be adjacent to some endpoint of the extent, or disjoint from it.  If
+     the insertion overlaps any existing extent, something is wrong.
+   */
+#ifdef ERROR_CHECK_EXTENTS
+  if (extent_start (extent) > indecks &&
+      extent_start (extent) < indecks + closure->length)
+    abort ();
+  if (extent_end (extent) > indecks &&
+      extent_end (extent) < indecks + closure->length)
+    abort ();
+#endif
+
+  /* The extent-adjustment code adjusted the extent's endpoints as if
+     they were markers -- endpoints at the gap (i.e. the insertion
+     point) go to the left of the insertion point, which is correct
+     for [) extents.  We need to fix the other kinds of extents.
+
+     Note that both conditions below will hold for zero-length (]
+     extents at the gap.  Zero-length () extents would get adjusted
+     such that their start is greater than their end; we treat them
+     as [) extents.  This is unfortunately an inelegant part of the
+     extent model, but there is no way around it. */
+
+  {
+    Memind new_start, new_end;
+
+    new_start = extent_start (extent);
+    new_end = extent_end (extent);
+    if (indecks == extent_start (extent) && extent_start_open_p (extent) &&
+	/* coerce zero-length () extents to [) */
+	new_start != new_end)
+      new_start += closure->length;
+    if (indecks == extent_end (extent) && !extent_end_open_p (extent))
+      new_end += closure->length;
+    set_extent_endpoints_1 (extent, new_start, new_end);
+  }
+
+  return 0;
+}
+
+void
+process_extents_for_insertion (Lisp_Object object, Bytind opoint,
+			       Bytecount length)
+{
+  struct process_extents_for_insertion_arg closure;
+
+  closure.opoint = opoint;
+  closure.length = length;
+  closure.object = object;
+  
+  map_extents_bytind (opoint, opoint + length,
+		      process_extents_for_insertion_mapper,
+		      (void *) &closure, object, 0,
+		      ME_END_CLOSED | ME_MIGHT_MODIFY_EXTENTS |
+		      ME_INCLUDE_INTERNAL);
+}
+
+/* ------------------------------------ */
+/*    process_extents_for_deletion()    */
+/* ------------------------------------ */
+
+struct process_extents_for_deletion_arg
+{
+  Memind start, end;
+  int destroy_included_extents;
+};
+
+/* This function is called when we're about to delete the range [from, to].
+   Detach all of the extents that are completely inside the range [from, to],
+   if they're detachable or open-open. */
+
+static int
+process_extents_for_deletion_mapper (EXTENT extent, void *arg)
+{
+  struct process_extents_for_deletion_arg *closure = 
+    (struct process_extents_for_deletion_arg *) arg;
+
+  /* If the extent lies completely within the range that
+     is being deleted, then nuke the extent if it's detachable
+     (otherwise, it will become a zero-length extent). */
+
+  if (closure->start <= extent_start (extent) &&
+      extent_end (extent) <= closure->end)
+    {
+      if (extent_detachable_p (extent))
+	{
+	  if (closure->destroy_included_extents)
+	    destroy_extent (extent);
+	  else
+	    extent_detach (extent);
+	}
+    }
+
+  return 0;
+}
+
+/* DESTROY_THEM means destroy the extents instead of just deleting them.
+   It is unused currently, but perhaps might be used (there used to
+   be a function process_extents_for_destruction(), #if 0'd out,
+   that did the equivalent). */
+void
+process_extents_for_deletion (Lisp_Object object, Bytind from,
+			      Bytind to, int destroy_them)
+{
+  struct process_extents_for_deletion_arg closure;
+
+  closure.start = buffer_or_string_bytind_to_memind (object, from);
+  closure.end = buffer_or_string_bytind_to_memind (object, to);
+  closure.destroy_included_extents = destroy_them;
+
+  map_extents_bytind (from, to, process_extents_for_deletion_mapper,
+		      (void *) &closure, object, 0,
+		      ME_END_CLOSED | ME_MIGHT_MODIFY_EXTENTS);
+}
+
+
+/************************************************************************/
+/*		    	extent properties				*/
+/************************************************************************/
+
+static void
+set_extent_invisible (EXTENT extent, Lisp_Object value)
+{
+  if (!EQ (extent_invisible (extent), value))
+    {
+      set_extent_invisible_1 (extent, value);
+      extent_changed_for_redisplay (extent, 1);
+    }
+}
+
+/* This function does "memoization" -- similar to the interning
+   that happens with symbols.  Given a list of faces, an equivalent
+   list is returned such that if this function is called twice with
+   input that is `equal', the resulting outputs will be `eq'.
+
+   Note that the inputs and outputs are in general *not* `equal' --
+   faces in symbol form become actual face objects in the output.
+   This is necessary so that temporary faces stay around. */
+
+static Lisp_Object
+memoize_extent_face_internal (Lisp_Object list)
+{
+  int len;
+  int thelen;
+  Lisp_Object cons, thecons;
+  Lisp_Object oldtail, tail;
+  struct gcpro gcpro1;
+
+  if (NILP (list))
+    return Qnil;
+  if (!CONSP (list))
+    return Fget_face (list);
+
+  /* To do the memoization, we use a hash table mapping from
+     external lists to internal lists.  We do `equal' comparisons
+     on the keys so the memoization works correctly.
+
+     Note that we canonicalize things so that the keys in the
+     hashtable (the external lists) always contain symbols and
+     the values (the internal lists) always contain face objects.
+
+     We also maintain a "reverse" table that maps from the internal
+     lists to the external equivalents.  The idea here is twofold:
+
+     1) `extent-face' wants to return a list containing face symbols
+        rather than face objects.
+     2) We don't want things to get quite so messed up if the user
+        maliciously side-effects the returned lists.
+     */
+
+  len = XINT (Flength (list));
+  thelen = XINT (Flength (Vextent_face_reusable_list));
+  oldtail = Qnil;
+  tail = Qnil;
+  GCPRO1 (oldtail);
+
+  /* We canonicalize the given list into another list.
+     We try to avoid consing except when necessary, so we have
+     a reusable list.
+  */
+  
+  if (thelen < len)
+    {
+      cons = Vextent_face_reusable_list;
+      while (!NILP (XCDR (cons)))
+	cons = XCDR (cons);
+      XCDR (cons) = Fmake_list (make_int (len - thelen), Qnil);
+    }
+  else if (thelen > len)
+    {
+      int i;
+
+      /* Truncate the list temporarily so it's the right length;
+	 remember the old tail. */
+      cons = Vextent_face_reusable_list;
+      for (i = 0; i < len - 1; i++)
+	cons = XCDR (cons);
+      tail = cons;
+      oldtail = XCDR (cons);
+      XCDR (cons) = Qnil;
+    }
+
+  thecons = Vextent_face_reusable_list;
+  EXTERNAL_LIST_LOOP (cons, list)
+    {
+      Lisp_Object face = Fget_face (XCAR (cons));
+
+      XCAR (thecons) = Fface_name (face);
+      thecons = XCDR (thecons);
+    }
+
+  list = Fgethash (Vextent_face_reusable_list, Vextent_face_memoize_hash_table,
+		   Qnil);
+  if (NILP (list))
+    {
+      Lisp_Object symlist = Fcopy_sequence (Vextent_face_reusable_list);
+      Lisp_Object facelist = Fcopy_sequence (Vextent_face_reusable_list);
+
+      LIST_LOOP (cons, facelist)
+	{
+	  XCAR (cons) = Fget_face (XCAR (cons));
+	}
+      Fputhash (symlist, facelist, Vextent_face_memoize_hash_table);
+      Fputhash (facelist, symlist, Vextent_face_reverse_memoize_hash_table);
+      list = facelist;
+    }
+
+  /* Now restore the truncated tail of the reusable list, if necessary. */
+  if (!NILP (tail))
+    XCDR (tail) = oldtail;
+
+  UNGCPRO;
+  return list;
+}
+
+static Lisp_Object
+external_of_internal_memoized_face (Lisp_Object face)
+{
+  if (NILP (face))
+    return Qnil;
+  else if (!CONSP (face))
+    return XFACE (face)->name;
+  else
+    {
+      face = Fgethash (face, Vextent_face_reverse_memoize_hash_table,
+		       Qunbound);
+      assert (!UNBOUNDP (face));
+      return face;
+    }
+}
+
+static Lisp_Object
+canonicalize_extent_property (Lisp_Object prop, Lisp_Object value)
+{
+  if (EQ (prop, Qface) || EQ (prop, Qmouse_face))
+    value = (external_of_internal_memoized_face
+	     (memoize_extent_face_internal (value)));
+  return value;
+}
+
+DEFUN ("extent-face", Fextent_face, Sextent_face, 1, 1, 0 /*
+Return the name of the face in which EXTENT is displayed, or nil
+if the extent's face is unspecified.  This might also return a list
+of face names.
+*/ )
+     (extent)
+     Lisp_Object extent;
+{
+  Lisp_Object face;
+
+  CHECK_EXTENT (extent);
+  face = extent_face (XEXTENT (extent));
+
+  return external_of_internal_memoized_face (face);
+}
+
+DEFUN ("set-extent-face", Fset_extent_face, Sset_extent_face, 2, 2, 0 /*
+Make the given EXTENT have the graphic attributes specified by FACE.
+FACE can also be a list of faces, and all faces listed will apply,
+with faces earlier in the list taking priority over those later in the
+list.
+*/ )
+     (extent, face)
+     Lisp_Object extent, face;
+{
+  EXTENT e;
+  Lisp_Object orig_face = face;
+
+  CHECK_EXTENT (extent);
+  e = XEXTENT (extent);
+  /* retrieve the ancestor for efficiency and proper redisplay noting. */
+  e = extent_ancestor (e);
+
+  face = memoize_extent_face_internal (face);
+
+  extent_face (e) = face;
+  extent_changed_for_redisplay (e, 1);
+
+  return orig_face;
+}
+
+
+DEFUN ("extent-mouse-face", Fextent_mouse_face, Sextent_mouse_face, 1, 1, 0 /*
+Return the face used to highlight EXTENT when the mouse passes over it.
+The return value will be a face name, a list of face names, or nil
+if the extent's mouse face is unspecified.
+*/ )
+     (extent)
+     Lisp_Object extent;
+{
+  Lisp_Object face;
+
+  CHECK_EXTENT (extent);
+  face = extent_mouse_face (XEXTENT (extent));
+
+  return external_of_internal_memoized_face (face);
+}
+
+DEFUN ("set-extent-mouse-face", Fset_extent_mouse_face, Sset_extent_mouse_face,
+       2, 2, 0 /*
+Set the face used to highlight EXTENT when the mouse passes over it.
+FACE can also be a list of faces, and all faces listed will apply,
+with faces earlier in the list taking priority over those later in the
+list.
+*/ )
+     (extent, face)
+     Lisp_Object extent, face;
+{
+  EXTENT e;
+  Lisp_Object orig_face = face;
+
+  CHECK_EXTENT (extent);
+  e = XEXTENT (extent);
+  /* retrieve the ancestor for efficiency and proper redisplay noting. */
+  e = extent_ancestor (e);
+
+  face = memoize_extent_face_internal (face);
+
+  set_extent_mouse_face (e, face);
+  extent_changed_for_redisplay (e, 1);
+
+  return orig_face;
+}
+
+void
+set_extent_glyph (EXTENT extent, Lisp_Object glyph, int endp,
+		  unsigned int layout)
+{
+  extent = extent_ancestor (extent);
+
+  if (!endp)
+    {
+      set_extent_begin_glyph (extent, glyph);
+      extent_begin_glyph_layout (extent) = layout;
+    }
+  else
+    {
+      set_extent_end_glyph (extent, glyph);
+      extent_end_glyph_layout (extent) = layout;
+    }
+
+  extent_changed_for_redisplay (extent, 1);
+}
+
+static Lisp_Object
+glyph_layout_to_symbol (unsigned int layout)
+{
+  switch (layout)
+    {
+    case GL_TEXT: return Qtext;
+    case GL_OUTSIDE_MARGIN: return Qoutside_margin;
+    case GL_INSIDE_MARGIN: return Qinside_margin;
+    case GL_WHITESPACE: return Qwhitespace;
+    default: abort ();
+    }
+  return Qnil;	/* shut up compiler */
+}
+
+static unsigned int
+symbol_to_glyph_layout (Lisp_Object layout_obj)
+{
+  unsigned int layout = 0;
+
+  if (NILP (layout_obj))
+    layout = GL_TEXT;
+  else
+    {
+      CHECK_SYMBOL (layout_obj);
+      if (EQ (Qoutside_margin, layout_obj))
+	layout = GL_OUTSIDE_MARGIN;
+      else if (EQ (Qinside_margin, layout_obj))
+	layout = GL_INSIDE_MARGIN;
+      else if (EQ (Qwhitespace, layout_obj))
+	layout = GL_WHITESPACE;
+      else if (EQ (Qtext, layout_obj))
+	layout = GL_TEXT;
+      else
+	signal_simple_error ("unknown glyph layout type", layout_obj);
+    }
+  return layout;
+}
+
+static Lisp_Object
+set_extent_glyph_1 (Lisp_Object extent_obj, Lisp_Object glyph, int endp,
+		    Lisp_Object layout_obj)
+{
+  EXTENT extent = decode_extent (extent_obj, DE_MUST_HAVE_BUFFER);
+  unsigned int layout = symbol_to_glyph_layout (layout_obj);
+
+  /* Make sure we've actually been given a glyph or it's nil (meaning
+     we're deleting a glyph from an extent). */
+  if (!NILP (glyph))
+    CHECK_GLYPH (glyph);
+
+  set_extent_glyph (extent, glyph, endp, layout);
+  return glyph;
+}
+
+DEFUN ("set-extent-begin-glyph", Fset_extent_begin_glyph, 
+       Sset_extent_begin_glyph, 2, 3, 0 /*
+Display a bitmap, subwindow or string at the beginning of EXTENT.
+BEGIN-GLYPH must be a glyph object.  The layout policy defaults to `text'.
+*/ )
+  (extent, begin_glyph, layout)
+   Lisp_Object extent, begin_glyph, layout;
+{
+  return set_extent_glyph_1 (extent, begin_glyph, 0, layout);
+}
+
+DEFUN ("set-extent-end-glyph", Fset_extent_end_glyph, 
+       Sset_extent_end_glyph, 2, 3, 0 /*
+Display a bitmap, subwindow or string at the end of the EXTENT.
+END-GLYPH must be a glyph object.  The layout policy defaults to `text'.
+*/ )
+  (extent, end_glyph, layout)
+   Lisp_Object extent, end_glyph, layout;
+{
+  return set_extent_glyph_1 (extent, end_glyph, 1, layout);
+}
+
+DEFUN ("extent-begin-glyph", Fextent_begin_glyph, Sextent_begin_glyph,
+       1, 1, 0 /*
+Return the glyph object displayed at the beginning of EXTENT.
+If there is none, nil is returned.
+*/ )
+     (extent_obj)
+     Lisp_Object extent_obj;
+{
+  return extent_begin_glyph (decode_extent (extent_obj, 0));
+}
+
+DEFUN ("extent-end-glyph", Fextent_end_glyph, Sextent_end_glyph, 1, 1, 0 /*
+Return the glyph object displayed at the end of EXTENT.
+If there is none, nil is returned.
+*/ )
+     (extent_obj)
+     Lisp_Object extent_obj;
+{
+  return extent_end_glyph (decode_extent (extent_obj, 0));
+}
+
+DEFUN ("set-extent-begin-glyph-layout", Fset_extent_begin_glyph_layout,
+       Sset_extent_begin_glyph_layout, 2, 2, 0 /*
+Set the layout policy of the given extent's begin glyph.
+Access this using the `extent-begin-glyph-layout' function.
+*/ )
+	(extent, layout)
+	Lisp_Object extent, layout;
+{
+  EXTENT e = decode_extent (extent, 0);
+  e = extent_ancestor (e);
+  extent_begin_glyph_layout (e) = symbol_to_glyph_layout (layout);
+  extent_maybe_changed_for_redisplay (e, 1);
+  return layout;
+}
+
+DEFUN ("set-extent-end-glyph-layout", Fset_extent_end_glyph_layout,
+       Sset_extent_end_glyph_layout, 2, 2, 0 /*
+Set the layout policy of the given extent's end glyph.
+Access this using the `extent-end-glyph-layout' function.
+*/ )
+	(extent, layout)
+	Lisp_Object extent, layout;
+{
+  EXTENT e = decode_extent (extent, 0);
+  e = extent_ancestor (e);
+  extent_end_glyph_layout (e) = symbol_to_glyph_layout (layout);
+  extent_maybe_changed_for_redisplay (e, 1);
+  return layout;
+}
+
+DEFUN ("extent-begin-glyph-layout", Fextent_begin_glyph_layout,
+       Sextent_begin_glyph_layout, 1, 1, 0 /*
+Return the layout policy associated with the given extent's begin glyph.
+Set this using the `set-extent-begin-glyph-layout' function.
+*/ )
+	(extent)
+	Lisp_Object extent;
+{
+  EXTENT e = decode_extent (extent, 0);
+  return glyph_layout_to_symbol (extent_begin_glyph_layout (e));
+}
+
+DEFUN ("extent-end-glyph-layout", Fextent_end_glyph_layout,
+       Sextent_end_glyph_layout, 1, 1, 0 /*
+Return the layout policy associated with the given extent's end glyph.
+Set this using the `set-extent-end-glyph-layout' function.
+*/ )
+	(extent)
+	Lisp_Object extent;
+{
+  EXTENT e = decode_extent (extent, 0);
+  return glyph_layout_to_symbol (extent_end_glyph_layout (e));
+}
+
+DEFUN ("set-extent-priority", Fset_extent_priority, Sset_extent_priority,
+       2, 2, 0 /*
+Changes the display priority of EXTENT.
+When the extent attributes are being merged for display, the priority
+is used to determine which extent takes precedence in the event of a
+conflict (two extents whose faces both specify font, for example: the
+font of the extent with the higher priority will be used).
+Extents are created with priority 0; priorities may be negative.
+*/ )
+	(extent, pri)
+	Lisp_Object extent, pri;
+{
+  EXTENT e = decode_extent (extent, 0);
+
+  CHECK_INT (pri);
+  e = extent_ancestor (e);
+  set_extent_priority (e, XINT (pri));
+  extent_maybe_changed_for_redisplay (e, 1);
+  return pri;
+}
+
+DEFUN ("extent-priority", Fextent_priority, Sextent_priority, 1, 1, 0 /*
+Return the display priority of EXTENT; see `set-extent-priority'.
+*/ )
+     (extent)
+     Lisp_Object extent;
+{
+  EXTENT e = decode_extent (extent, 0);
+  return make_int (extent_priority (e));
+}
+
+DEFUN ("set-extent-property", Fset_extent_property, Sset_extent_property,
+       3, 3, 0 /*
+Change a property of an extent.
+PROPERTY may be any symbol; the value stored may be accessed with
+ the `extent-property' function.
+The following symbols have predefined meanings:
+
+ detached           Removes the extent from its buffer; setting this is
+                    the same as calling `detach-extent'.
+                    
+ destroyed          Removes the extent from its buffer, and makes it
+                    unusable in the future; this is the same calling
+                    `delete-extent'.
+                    
+ priority           Change redisplay priority; same as `set-extent-priority'.
+                    
+ start-open         Whether the set of characters within the extent is
+                    treated being open on the left, that is, whether
+                    the start position is an exclusive, rather than
+                    inclusive, boundary.  If true, then characters
+                    inserted exactly at the beginning of the extent
+                    will remain outside of the extent; otherwise they
+                    will go into the extent, extending it.
+                    
+ end-open           Whether the set of characters within the extent is
+                    treated being open on the right, that is, whether
+                    the end position is an exclusive, rather than
+                    inclusive, boundary.  If true, then characters
+                    inserted exactly at the end of the extent will
+                    remain outside of the extent; otherwise they will
+                    go into the extent, extending it.
+                    
+                    By default, extents have the `end-open' but not the
+                    `start-open' property set.
+                    
+ read-only          Text within this extent will be unmodifiable.
+                    
+ detachable         Whether the extent gets detached (as with
+                    `detach-extent') when all the text within the
+                    extent is deleted.  This is true by default.  If
+                    this property is not set, the extent becomes a
+                    zero-length extent when its text is deleted. (In
+                    such a case, the `start-open' property is
+                    automatically removed if both the `start-open' and
+                    `end-open' properties are set, since zero-length
+                    extents open on both ends are not allowed.)
+              
+ face               The face in which to display the text.  Setting
+                    this is the same as calling `set-extent-face'.
+
+ mouse-face	    If non-nil, the extent will be highlighted in this
+		    face when the mouse moves over it.
+
+ pointer            If non-nil, and a valid pointer glyph, this specifies
+                    the shape of the mouse pointer while over the extent.
+
+ highlight          Obsolete: Setting this property is equivalent to
+		    setting a `mouse-face' property of `highlight'.
+		    Reading this property returns non-nil if
+		    the extent has a non-nil `mouse-face' property.
+                    
+ duplicable         Whether this extent should be copied into strings,
+                    so that kill, yank, and undo commands will restore
+                    or copy it.  `duplicable' extents are copied from
+                    an extent into a string when `buffer-substring' or
+                    a similar function creates a string.  The extents
+                    in a string are copied into other strings created
+                    from the string using `concat' or `substring'.
+                    When `insert' or a similar function inserts the
+                    string into a buffer, the extents are copied back
+                    into the buffer.
+                    
+ replicating        Meaningful only in conjunction with `duplicable'.
+                    If this flag is set, extents that are copied from
+                    buffers into strings are made children of the
+                    original extent.  When the string is pasted back
+                    into a buffer, the same extent (i.e. the `eq'
+                    predicate applies) that was originally in the
+                    buffer will be used if possible -- i.e. if the
+                    extent is detached or the paste location abuts or
+                    overlaps the extent.  This behavior is compatible
+                    with the old "extent replica" behavior and was
+                    apparently required by Energize.
+                    
+ unique             Meaningful only in conjunction with `duplicable'
+                    and `replicating'.  When this is set, there may be
+                    only one instance of this extent attached at a
+                    time: if it is copied to the kill ring and then
+                    yanked, the extent is not copied.  If, however, it
+                    is killed (removed from the buffer) and then
+                    yanked, it will be re-attached at the new
+                    position.
+                    
+ invisible          If the value is non-nil, text under this extent
+                    may be treated as not present for the purpose of
+                    redisplay, or may be displayed using an ellipsis
+                    or other marker; see `buffer-invisibility-spec'
+                    and `invisible-text-glyph'.  In all cases,
+                    however, the text is still visible to other
+                    functions that examine a buffer's text.
+                   
+ keymap             This keymap is consulted for mouse clicks on this
+                    extent, or keypresses made while point is within the
+                    extent.
+                    
+ copy-function      This is a hook that is run when a duplicable extent
+                    is about to be copied from a buffer to a string (or
+                    the kill ring).  It is called with three arguments,
+                    the extent, and the buffer-positions within it
+                    which are being copied.  If this function returns
+                    nil, then the extent will not be copied; otherwise
+                    it will.
+                    
+ paste-function     This is a hook that is run when a duplicable extent is
+                    about to be copied from a string (or the kill ring)
+                    into a buffer.  It is called with three arguments,
+                    the original extent, and the buffer positions which
+                    the copied extent will occupy.  (This hook is run
+                    after the corresponding text has already been
+                    inserted into the buffer.)  Note that the extent
+                    argument may be detached when this function is run.
+                    If this function returns nil, no extent will be
+                    inserted.  Otherwise, there will be an extent
+                    covering the range in question.
+                    
+                    If the original extent is not attached to a buffer,
+                    then it will be re-attached at this range.
+                    Otherwise, a copy will be made, and that copy
+                    attached here.
+                    
+                    The copy-function and paste-function are meaningful
+                    only for extents with the `duplicable' flag set,
+                    and if they are not specified, behave as if `t' was
+                    the returned value.  When these hooks are invoked,
+                    the current buffer is the buffer which the extent
+                    is being copied from/to, respectively.
+                    
+ begin-glyph        A glyph to be displayed at the beginning of the extent,
+                    or nil.
+                    
+ end-glyph          A glyph to be displayed at the end of the extent,
+                    or nil.
+
+ begin-glyph-layout The layout policy (one of `text', `whitespace',
+                    `inside-margin', or `outside-margin') of the extent's
+                    begin glyph.
+
+ end-glyph-layout   The layout policy of the extent's end glyph.
+*/ )
+     (extent, property, value)
+     Lisp_Object extent, property, value;
+{
+  /* This function can GC if property is `keymap' */
+  EXTENT e = decode_extent (extent, 0);
+  CHECK_SYMBOL (property);
+
+  if (EQ (property, Qread_only))
+    set_extent_read_only (e, value);
+  else if (EQ (property, Qunique))
+    extent_unique_p (e) = !NILP (value);
+  else if (EQ (property, Qduplicable))
+    extent_duplicable_p (e) = !NILP (value);
+  else if (EQ (property, Qreplicating))
+    extent_replicating_p (e) = !NILP (value);
+  else if (EQ (property, Qinvisible))
+    set_extent_invisible (e, value);
+  else if (EQ (property, Qdetachable))
+    extent_detachable_p (e) = !NILP (value);
+
+  else if (EQ (property, Qdetached))
+    {
+      if (NILP (value))
+	error ("can only set `detached' to t");
+      Fdetach_extent (extent);
+    }
+  else if (EQ (property, Qdestroyed))
+    {
+      if (NILP (value))
+	error ("can only set `destroyed' to t");
+      Fdelete_extent (extent);
+    }
+  else if (EQ (property, Qpriority))
+    Fset_extent_priority (extent, value);
+  else if (EQ (property, Qface))
+    Fset_extent_face (extent, value);
+  else if (EQ (property, Qmouse_face))
+    Fset_extent_mouse_face (extent, value);
+  /* Obsolete: */
+  else if (EQ (property, Qhighlight))
+    Fset_extent_mouse_face (extent, Qhighlight); 
+  else if (EQ (property, Qbegin_glyph_layout))
+    Fset_extent_begin_glyph_layout (extent, value);
+  else if (EQ (property, Qend_glyph_layout))
+    Fset_extent_end_glyph_layout (extent, value);
+  /* For backwards compatibility.  We use begin glyph because it is by
+     far the more used of the two. */
+  else if (EQ (property, Qglyph_layout))
+    Fset_extent_begin_glyph_layout (extent, value);
+  else if (EQ (property, Qbegin_glyph))
+    Fset_extent_begin_glyph (extent, value, Qnil);
+  else if (EQ (property, Qend_glyph))
+    Fset_extent_end_glyph (extent, value, Qnil);
+  else if (EQ (property, Qstart_open) ||
+	   EQ (property, Qend_open) ||
+	   EQ (property, Qstart_closed) ||
+	   EQ (property, Qend_closed))
+    {
+      int start_open = -1, end_open = -1;
+      if (EQ (property, Qstart_open))
+	start_open = !NILP (value);
+      else if (EQ (property, Qend_open))
+	end_open = !NILP (value);
+      /* Support (but don't document...) the obvious antonyms. */
+      else if (EQ (property, Qstart_closed))
+	start_open = NILP (value);
+      else
+	end_open = NILP (value);
+      set_extent_openness (e, start_open, end_open);
+    }
+  else
+    {
+      if (EQ (property, Qkeymap))
+	while (NILP (Fkeymapp (value)))
+	  value = wrong_type_argument (Qkeymapp, value);
+
+      external_plist_put (extent_plist_addr (e), property, value, 0, ERROR_ME);
+    }
+
+  return value;
+}
+
+DEFUN ("extent-property", Fextent_property, Sextent_property, 2, 3, 0 /*
+Return EXTENT's value for property PROPERTY.
+See `set-extent-property' for the built-in property names.
+*/ )
+  (extent, property, defalt)
+   Lisp_Object extent, property, defalt;
+{
+  EXTENT e = decode_extent (extent, 0);
+  CHECK_SYMBOL (property);
+
+  if      (EQ (property, Qdetached))
+    return (extent_detached_p (e) ? Qt : Qnil);
+  else if (EQ (property, Qdestroyed))
+    return (!EXTENT_LIVE_P (e) ? Qt : Qnil);
+#define RETURN_FLAG(flag) \
+  return (extent_normal_field (e, flag) ? Qt : Qnil)
+  else if (EQ (property, Qstart_open))	 RETURN_FLAG (start_open);
+  else if (EQ (property, Qend_open))	 RETURN_FLAG (end_open);
+  else if (EQ (property, Qunique))	 RETURN_FLAG (unique);
+  else if (EQ (property, Qduplicable))	 RETURN_FLAG (duplicable);
+  else if (EQ (property, Qreplicating))	 RETURN_FLAG (replicating);
+  else if (EQ (property, Qdetachable))	 RETURN_FLAG (detachable);
+#undef RETURN_FLAG
+  /* Support (but don't document...) the obvious antonyms. */
+  else if (EQ (property, Qstart_closed))
+    return (extent_start_open_p (e) ? Qnil : Qt);
+  else if (EQ (property, Qend_closed))
+    return (extent_end_open_p (e) ? Qnil : Qt);
+  else if (EQ (property, Qpriority))
+    return make_int (extent_priority (e));
+  else if (EQ (property, Qread_only))
+    return extent_read_only (e);
+  else if (EQ (property, Qinvisible))
+    return extent_invisible (e);
+  else if (EQ (property, Qface))
+    return Fextent_face (extent);
+  else if (EQ (property, Qmouse_face))
+    return Fextent_mouse_face (extent);
+  /* Obsolete: */
+  else if (EQ (property, Qhighlight))
+    return !NILP (Fextent_mouse_face (extent)) ? Qt : Qnil;
+  else if (EQ (property, Qbegin_glyph_layout))
+    return Fextent_begin_glyph_layout (extent);
+  else if (EQ (property, Qend_glyph_layout))
+    return Fextent_end_glyph_layout (extent);
+  /* For backwards compatibility.  We use begin glyph because it is by
+     far the more used of the two. */
+  else if (EQ (property, Qglyph_layout))
+    return Fextent_begin_glyph_layout (extent);
+  else if (EQ (property, Qbegin_glyph))
+    return extent_begin_glyph (e);
+  else if (EQ (property, Qend_glyph))
+    return extent_end_glyph (e);
+  else
+    {
+      Lisp_Object value;
+
+      value = external_plist_get (extent_plist_addr (e), property, 0,
+				  ERROR_ME);
+      if (UNBOUNDP (value))
+	return defalt;
+      return value;
+    }
+}
+
+DEFUN ("extent-properties", Fextent_properties, Sextent_properties, 1, 1, 0 /*
+Return a property list of the attributes of the given extent.
+Do not modify this list; use `set-extent-property' instead.
+*/ )
+  (extent)
+   Lisp_Object extent;
+{
+  EXTENT e, anc;
+  Lisp_Object result, face, anc_obj = Qnil;
+
+  CHECK_EXTENT (extent);
+  e = XEXTENT (extent);
+  if (!EXTENT_LIVE_P (e))
+    return Fcons (Qdestroyed, Fcons (Qt, Qnil));
+
+  anc = extent_ancestor (e);
+  XSETEXTENT (anc_obj, anc);
+
+  /* For efficiency, use the ancestor for all properties except detached */
+
+  result = extent_plist_slot (anc);
+  face = Fextent_face (anc_obj);
+  if (!NILP (face))
+    result = Fcons (Qface, Fcons (face, result));
+  face = Fextent_mouse_face (anc_obj);
+  if (!NILP (face))
+    result = Fcons (Qmouse_face, Fcons (face, result));
+
+  /* For now continue to include this for backwards compatibility. */
+  if (extent_begin_glyph_layout (anc) != GL_TEXT)
+    result = Fcons (Qglyph_layout,
+		    glyph_layout_to_symbol (extent_begin_glyph_layout (anc)));
+
+  if (extent_begin_glyph_layout (anc) != GL_TEXT)
+    result = Fcons (Qbegin_glyph_layout,
+		    glyph_layout_to_symbol (extent_begin_glyph_layout (anc)));
+  if (extent_end_glyph_layout (anc) != GL_TEXT)
+    result = Fcons (Qend_glyph_layout,
+		    glyph_layout_to_symbol (extent_end_glyph_layout (anc)));
+
+  if (!NILP (extent_end_glyph (anc)))
+    result = Fcons (Qend_glyph, Fcons (extent_end_glyph (anc), result));
+  if (!NILP (extent_begin_glyph (anc)))
+    result = Fcons (Qbegin_glyph, Fcons (extent_begin_glyph (anc), result));
+
+  if (extent_priority (anc) != 0)
+    result = Fcons (Qpriority, Fcons (make_int (extent_priority (anc)),
+				      result));
+
+  if (!NILP (extent_invisible (anc)))
+    result = Fcons (Qinvisible, Fcons (extent_invisible (anc), result));
+
+  if (!NILP (extent_read_only (anc)))
+    result = Fcons (Qread_only, Fcons (extent_read_only (anc), result));
+
+#define CONS_FLAG(flag, sym) if (extent_normal_field (anc, flag)) \
+  result = Fcons (sym, Fcons (Qt, result))
+  CONS_FLAG (end_open, Qend_open);
+  CONS_FLAG (start_open, Qstart_open);
+  CONS_FLAG (replicating, Qreplicating);
+  CONS_FLAG (detachable, Qdetachable);
+  CONS_FLAG (duplicable, Qduplicable);
+  CONS_FLAG (unique, Qunique);
+#undef CONS_FLAG
+
+  /* detached is not an inherited property */
+  if (extent_detached_p (e))
+    result = Fcons (Qdetached, Fcons (Qt, result));
+
+  return result;
+}
+
+
+/************************************************************************/
+/*		    	     highlighting      				*/
+/************************************************************************/
+
+/* The display code looks into the Vlast_highlighted_extent variable to 
+   correctly display highlighted extents.  This updates that variable,
+   and marks the appropriate buffers as needing some redisplay.
+ */
+static void
+do_highlight (Lisp_Object extent_obj, int highlight_p)
+{
+  if (( highlight_p && (EQ (Vlast_highlighted_extent, extent_obj))) ||
+      (!highlight_p && (EQ (Vlast_highlighted_extent, Qnil))))
+    return;
+  if (EXTENTP (Vlast_highlighted_extent) &&
+      EXTENT_LIVE_P (XEXTENT (Vlast_highlighted_extent)))
+    {
+      /* do not recurse on descendants.  Only one extent is highlighted
+	 at a time. */
+      extent_changed_for_redisplay (XEXTENT (Vlast_highlighted_extent), 0);
+    }
+  Vlast_highlighted_extent = Qnil;
+  if (!NILP (extent_obj)
+      && BUFFERP (extent_object (XEXTENT (extent_obj)))
+      && highlight_p)
+    {
+      extent_changed_for_redisplay (XEXTENT (extent_obj), 0);
+      Vlast_highlighted_extent = extent_obj;
+    }
+}
+
+DEFUN ("force-highlight-extent", Fforce_highlight_extent, 
+       Sforce_highlight_extent, 1, 2, 0 /*
+Highlight or unhighlight the given extent.
+If the second arg is non-nil, it will be highlighted, else dehighlighted.
+This is the same as `highlight-extent', except that it will work even
+on extents without the `mouse-face' property.
+*/ )
+     (extent_obj, highlight_p)
+     Lisp_Object extent_obj, highlight_p;
+{
+  if (NILP (extent_obj))
+    highlight_p = Qnil;
+  else
+    XSETEXTENT (extent_obj, decode_extent (extent_obj, DE_MUST_BE_ATTACHED));
+  do_highlight (extent_obj, !NILP (highlight_p));
+  return Qnil;
+}
+
+DEFUN ("highlight-extent", Fhighlight_extent, Shighlight_extent, 1, 2, 0 /*
+Highlight the given extent, if it is highlightable
+\(that is, if it has the `mouse-face' property).
+If the second arg is non-nil, it will be highlighted, else dehighlighted.
+Highlighted extents are displayed as if they were merged with the face
+or faces specified by the `mouse-face' property.
+*/ )
+     (extent_obj, highlight_p)
+     Lisp_Object extent_obj, highlight_p;
+{
+  if (EXTENTP (extent_obj) && NILP (extent_mouse_face (XEXTENT (extent_obj))))
+    return Qnil;
+  else
+    return (Fforce_highlight_extent (extent_obj, highlight_p));
+}
+
+
+/************************************************************************/
+/*			   strings and extents				*/
+/************************************************************************/
+
+/* copy/paste hooks */
+
+static int
+run_extent_copy_paste_internal (EXTENT e, Bufpos from, Bufpos to,
+				Lisp_Object object,
+				Lisp_Object prop)
+{
+  /* This function can GC */
+  Lisp_Object extent;
+  Lisp_Object copy_fn;
+  XSETEXTENT (extent, e);
+  copy_fn = Fextent_property (extent, prop, Qnil);
+  if (!NILP (copy_fn))
+    {
+      Lisp_Object flag;
+      struct gcpro gcpro1, gcpro2, gcpro3;
+      GCPRO3 (extent, copy_fn, object);
+      if (BUFFERP (object))
+	flag = call3_in_buffer (XBUFFER (object), copy_fn, extent,
+				make_int (from), make_int (to));
+      else
+	flag = call3 (copy_fn, extent, make_int (from), make_int (to));
+      UNGCPRO;
+      if (NILP (flag) || !EXTENT_LIVE_P (XEXTENT (extent)))
+	return 0;
+    }
+  return 1;
+}
+
+static int
+run_extent_copy_function (EXTENT e, Bytind from, Bytind to)
+{
+  Lisp_Object object = extent_object (e);
+  /* This function can GC */
+  return run_extent_copy_paste_internal
+    (e, buffer_or_string_bytind_to_bufpos (object, from),
+     buffer_or_string_bytind_to_bufpos (object, to), object,
+     Qcopy_function);
+}
+
+static int
+run_extent_paste_function (EXTENT e, Bytind from, Bytind to,
+			   Lisp_Object object)
+{
+  /* This function can GC */
+  return run_extent_copy_paste_internal
+    (e, buffer_or_string_bytind_to_bufpos (object, from),
+     buffer_or_string_bytind_to_bufpos (object, to), object,
+     Qpaste_function);
+}
+
+static void   
+update_extent (EXTENT extent, Bytind from, Bytind to)
+{
+  set_extent_endpoints (extent, from, to, Qnil);
+/* #### remove this crap */
+#ifdef ENERGIZE
+  restore_energize_extent_state (extent);
+#endif
+}
+
+/* Insert an extent, usually from the dup_list of a string which
+   has just been inserted.
+   This code does not handle the case of undo.
+   */
+static Lisp_Object
+insert_extent (EXTENT extent, Bytind new_start, Bytind new_end,
+	       Lisp_Object object, int run_hooks)
+{
+  /* This function can GC */
+  Lisp_Object tmp;
+
+  if (!EQ (extent_object (extent), object))
+    goto copy_it;
+
+  if (extent_detached_p (extent))
+    {
+      if (run_hooks &&
+	  !run_extent_paste_function (extent, new_start, new_end, object))
+	/* The paste-function said don't re-attach this extent here. */
+	return Qnil;
+      else
+	update_extent (extent, new_start, new_end);
+    }
+  else
+    {
+      Bytind exstart = extent_endpoint_bytind (extent, 0);
+      Bytind exend = extent_endpoint_bytind (extent, 1);
+      
+      if (exend < new_start || exstart > new_end)
+	goto copy_it;
+      else
+	{
+	  new_start = min (exstart, new_start);
+	  new_end = max (exend, new_end);
+	  if (exstart != new_start || exend != new_end)
+	    update_extent (extent, new_start, new_end);
+	}
+    }
+
+  XSETEXTENT (tmp, extent);
+  return tmp;
+
+ copy_it:
+  if (run_hooks &&
+      !run_extent_paste_function (extent, new_start, new_end, object))
+    /* The paste-function said don't attach a copy of the extent here. */
+    return Qnil;
+  else
+    {
+      XSETEXTENT (tmp, copy_extent (extent, new_start, new_end, object));
+      return tmp;
+    }
+}
+
+DEFUN ("insert-extent", Finsert_extent, Sinsert_extent, 1, 5, 0 /*
+Insert EXTENT from START to END in BUFFER-OR-STRING.
+BUFFER-OR-STRING defaults to the current buffer if omitted.
+This operation does not insert any characters,
+but otherwise acts as if there were a replicating extent whose
+parent is EXTENT in some string that was just inserted.
+Returns the newly-inserted extent.
+The fourth arg, NO-HOOKS, can be used to inhibit the running of the
+ extent's `paste-function' property if it has one.
+See documentation on `detach-extent' for a discussion of undo recording.
+*/ )
+  (extent, start, end, no_hooks, buffer_or_string)
+   Lisp_Object extent, start, end, no_hooks, buffer_or_string;
+{
+  EXTENT ext = decode_extent (extent, 0);
+  Lisp_Object copy;
+  Bytind s, e;
+
+  buffer_or_string = decode_buffer_or_string (buffer_or_string);
+  get_buffer_or_string_range_byte (buffer_or_string, start, end, &s, &e,
+				   GB_ALLOW_PAST_ACCESSIBLE);
+
+  copy = insert_extent (ext, s, e, buffer_or_string, NILP (no_hooks));
+  if (EXTENTP (copy))
+    {
+      if (extent_duplicable_p (XEXTENT (copy)))
+	record_extent (copy, 1);
+    }
+  return copy;
+}
+
+
+/* adding buffer extents to a string */
+
+struct add_string_extents_arg
+{
+  Bytind from;
+  Bytecount length;
+  Lisp_Object string;
+};
+
+static int
+add_string_extents_mapper (EXTENT extent, void *arg)
+{
+  /* This function can GC */
+  struct add_string_extents_arg *closure = 
+    (struct add_string_extents_arg *) arg;
+  Bytecount start = extent_endpoint_bytind (extent, 0) - closure->from;
+  Bytecount end = extent_endpoint_bytind (extent, 1) - closure->from;
+  
+  if (extent_duplicable_p (extent))
+    {
+      EXTENT e;
+
+      start = max (start, 0);
+      end = min (end, closure->length);
+
+      /* Run the copy-function to give an extent the option of
+	 not being copied into the string (or kill ring).
+	 */
+      if (extent_duplicable_p (extent) &&
+	  !run_extent_copy_function (extent, start + closure->from,
+				     end + closure->from))
+	return 0;
+      e = copy_extent (extent, start, end, closure->string);
+      if (extent_replicating_p (extent))
+	{
+	  Lisp_Object e_obj = Qnil, extent_obj = Qnil;
+
+	  XSETEXTENT (e_obj, e);
+	  XSETEXTENT (extent_obj, extent);
+	  Fset_extent_parent (e_obj, extent_obj);
+	}
+    }
+
+  return 0;
+}
+
+/* Add the extents in buffer BUF from OPOINT to OPOINT+LENGTH to
+   the string STRING. */
+void 
+add_string_extents (Lisp_Object string, struct buffer *buf, Bytind opoint,
+		    Bytecount length)
+{
+  /* This function can GC */
+  struct add_string_extents_arg closure;
+  struct gcpro gcpro1, gcpro2;
+  Lisp_Object buffer;
+
+  closure.from = opoint;
+  closure.length = length;
+  closure.string = string;
+  buffer = make_buffer (buf);
+  GCPRO2 (buffer, string);
+  map_extents_bytind (opoint, opoint + length, add_string_extents_mapper, 
+		      (void *) &closure, buffer, 0,
+		      /* ignore extents that just abut the region */
+		      ME_END_CLOSED | ME_ALL_EXTENTS_OPEN |
+		      /* we are calling E-Lisp (the extent's copy function)
+			 so anything might happen */
+		      ME_MIGHT_CALL_ELISP);
+  UNGCPRO;
+}
+
+struct splice_in_string_extents_arg
+{
+  Bytecount pos;
+  Bytecount length;
+  Bytind opoint;
+  Lisp_Object buffer;
+};
+
+static int
+splice_in_string_extents_mapper (EXTENT extent, void *arg)
+{
+  /* This function can GC */
+  struct splice_in_string_extents_arg *closure = 
+    (struct splice_in_string_extents_arg *) arg;
+  /* BASE_START and BASE_END are the limits in the buffer of the string
+     that was just inserted.
+
+     NEW_START and NEW_END are the prospective buffer positions of the
+     extent that is going into the buffer. */
+  Bytind base_start = closure->opoint;
+  Bytind base_end = base_start + closure->length;
+  Bytind new_start = (base_start + extent_endpoint_bytind (extent, 0) -
+		      closure->pos);
+  Bytind new_end = (base_start + extent_endpoint_bytind (extent, 1) -
+		    closure->pos);
+
+  if (new_start < base_start)
+    new_start = base_start;
+  if (new_end > base_end)
+    new_end = base_end;
+  if (new_end <= new_start)
+    return 0;
+
+  if (!extent_duplicable_p (extent))
+    return 0;
+
+  if (!extent_replicating_p (extent))
+    {
+      if (!inside_undo &&
+	  !run_extent_paste_function (extent, new_start, new_end,
+				      closure->buffer))
+	return 0;
+      copy_extent (extent, new_start, new_end, closure->buffer);
+    }
+  else
+    {
+      Bytind parstart = 0;
+      Bytind parend = 0;
+      Lisp_Object parent_obj = extent_parent (extent);
+      EXTENT parent;
+
+      if (!EXTENTP (parent_obj))
+	return 0;
+      parent = XEXTENT (parent_obj);
+      if (!EXTENT_LIVE_P (parent))
+	return 0;
+
+      if (!extent_detached_p (parent))
+	{
+	  parstart = extent_endpoint_bytind (parent, 0);
+	  parend = extent_endpoint_bytind (parent, 1);
+	}
+
+/* #### remove this crap */
+#ifdef ENERGIZE
+      /* Energize extents like toplevel-forms can only be pasted 
+	 in the buffer they come from.  This should be parametrized
+	 in the generic extent objects.  Right now just silently
+	 skip the extents if it's not from the same buffer.
+	 */
+      if (!EQ (extent_object (parent), closure->buffer)
+	  && energize_extent_data (parent))
+	return 0;
+#endif
+	  
+      /* If this is a `unique' extent, and it is currently attached
+	 somewhere other than here (non-overlapping), then don't copy
+	 it (that's what `unique' means).  If however it is detached,
+	 or if we are inserting inside/adjacent to the original
+	 extent, then insert_extent() will simply reattach it, which
+	 is what we want.
+	 */
+      if (extent_unique_p (parent)
+	  && !extent_detached_p (parent)
+	  && (!EQ (extent_object (parent), closure->buffer)
+	      || parend > new_end
+	      || parstart < new_start))
+	return 0;
+  
+      insert_extent (parent, new_start, new_end,
+		     closure->buffer, !inside_undo);
+    }
+  return 0;
+}
+
+/* We have just inserted a section of STRING (starting at POS, of
+   length LENGTH) into buffer BUF at OPOINT.  Do whatever is necessary
+   to get the string's extents into the buffer. */
+
+void 
+splice_in_string_extents (Lisp_Object string, struct buffer *buf,
+			  Bytind opoint, Bytecount length, Bytecount pos)
+{
+  struct splice_in_string_extents_arg closure;
+  struct gcpro gcpro1, gcpro2;
+  Lisp_Object buffer;
+
+  buffer = make_buffer (buf);
+  closure.opoint = opoint;
+  closure.pos = pos;
+  closure.length = length;
+  closure.buffer = buffer;
+  GCPRO2 (buffer, string);
+  map_extents_bytind (pos, pos + length,
+		      splice_in_string_extents_mapper, 
+		      (void *) &closure, string, 0,
+		      /* ignore extents that just abut the region */
+		      ME_END_CLOSED | ME_ALL_EXTENTS_OPEN |
+		      /* we are calling E-Lisp (the extent's copy function)
+			 so anything might happen */
+		      ME_MIGHT_CALL_ELISP);
+  UNGCPRO;
+}
+
+struct copy_string_extents_arg
+{
+  Bytecount new_pos;
+  Bytecount old_pos;
+  Bytecount length;
+  Lisp_Object new_string;
+};
+
+struct copy_string_extents_1_arg
+{
+  Lisp_Object parent_in_question;
+  EXTENT found_extent;
+};
+  
+static int
+copy_string_extents_1_mapper (EXTENT extent, void *arg)
+{
+  struct copy_string_extents_1_arg *closure = 
+    (struct copy_string_extents_1_arg *) arg;
+
+  if (extent_replicating_p (extent) &&
+      EQ (extent_parent (extent), closure->parent_in_question))
+    {
+      closure->found_extent = extent;
+      return 1; /* stop mapping */
+    }
+
+  return 0;
+}
+
+static int
+copy_string_extents_mapper (EXTENT extent, void *arg)
+{
+  struct copy_string_extents_arg *closure = 
+    (struct copy_string_extents_arg *) arg;
+  Bytecount old_start, old_end;
+  Bytecount new_start, new_end;
+
+  old_start = extent_endpoint_bytind (extent, 0);
+  old_end = extent_endpoint_bytind (extent, 1);
+
+  old_start = max (closure->old_pos, old_start);
+  old_end = min (closure->old_pos + closure->length, old_end);
+
+  if (old_start >= old_end)
+    return 0;
+
+  new_start = old_start + closure->new_pos - closure->old_pos;
+  new_end = old_end + closure->new_pos - closure->old_pos;
+
+  if (extent_replicating_p (extent))
+    {
+      struct copy_string_extents_1_arg closure_1;
+
+      closure_1.parent_in_question = extent_parent (extent);
+      closure_1.found_extent = 0;
+
+      /* When adding a replicating extent, we need to make sure
+	 that there isn't an existing replicating extent referring
+	 to the same parent extent that abuts or overlaps.  If so,
+	 we merge with that extent rather than adding anew. */
+      map_extents_bytind (closure->old_pos, closure->old_pos + closure->length,
+			  copy_string_extents_1_mapper,
+			  (void *) &closure, closure->new_string, 0,
+			  /* get all extents that abut the region */
+			  ME_END_CLOSED | ME_ALL_EXTENTS_CLOSED);
+      if (closure_1.found_extent)
+	{
+	  Bytecount exstart =
+	    extent_endpoint_bytind (closure_1.found_extent, 0);
+	  Bytecount exend =
+	    extent_endpoint_bytind (closure_1.found_extent, 1);
+	  exstart = min (exstart, new_start);
+	  exend = max (exend, new_end);
+	  set_extent_endpoints (closure_1.found_extent, exstart, exend, Qnil);
+	  return 0;
+	}
+    }
+      
+  copy_extent (extent,
+	       old_start + closure->new_pos - closure->old_pos,
+	       old_end + closure->new_pos - closure->old_pos,
+	       closure->new_string);
+  return 0;
+}
+
+/* The string NEW_STRING was partially constructed from OLD_STRING.
+   In particular, the section of length LEN starting at NEW_POS in
+   NEW_STRING came from the section of the same length starting at
+   OLD_POS in OLD_STRING.  Copy the extents as appropriate. */
+
+void 
+copy_string_extents (Lisp_Object new_string, Lisp_Object old_string,
+		     Bytecount new_pos, Bytecount old_pos,
+		     Bytecount length)
+{
+  struct copy_string_extents_arg closure;
+  struct gcpro gcpro1, gcpro2;
+
+  closure.new_pos = new_pos;
+  closure.old_pos = old_pos;
+  closure.new_string = new_string;
+  closure.length = length;
+  GCPRO2 (new_string, old_string);
+  map_extents_bytind (old_pos, old_pos + length,
+		      copy_string_extents_mapper,
+		      (void *) &closure, old_string, 0,
+		      /* ignore extents that just abut the region */
+		      ME_END_CLOSED | ME_ALL_EXTENTS_OPEN |
+		      /* we are calling E-Lisp (the extent's copy function)
+			 so anything might happen */
+		      ME_MIGHT_CALL_ELISP);
+  UNGCPRO;
+}
+
+/* Checklist for sanity checking:
+   - {kill, yank, copy} at {open, closed} {start, end} of {writable, read-only} extent
+   - {kill, copy} & yank {once, repeatedly} duplicable extent in {same, different} buffer
+ */
+
+
+/************************************************************************/
+/*				text properties				*/
+/************************************************************************/
+
+/* Text properties
+   Originally this stuff was implemented in lisp (all of the functionality
+   exists to make that possible) but speed was a problem.
+ */
+
+Lisp_Object Qtext_prop;
+Lisp_Object Qtext_prop_extent_paste_function;
+
+static Lisp_Object
+get_text_property_bytind (Bytind position, Lisp_Object prop,
+			  Lisp_Object object, enum extent_at_flag fl,
+			  int text_props_only)
+{
+  Lisp_Object extent;
+
+  /* text_props_only specifies whether we only consider text-property
+     extents (those with the 'text-prop property set) or all extents. */
+  if (!text_props_only)
+    extent = extent_at_bytind (position, object, prop, 0, fl);
+  else
+    {
+      EXTENT prior = 0;
+      while (1)
+	{
+	  extent = extent_at_bytind (position, object, Qtext_prop, prior,
+				     fl);
+	  if (NILP (extent))
+	    return Qnil;
+	  if (EQ (prop, Fextent_property (extent, Qtext_prop, Qnil)))
+	    break;
+	  prior = XEXTENT (extent);
+	}
+    }
+
+  if (!NILP (extent))
+    return Fextent_property (extent, prop, Qnil);
+  if (!NILP (Vdefault_text_properties))
+    return Fplist_get (Vdefault_text_properties, prop, Qnil);
+  return Qnil;
+}
+
+static Lisp_Object
+get_text_property_1 (Lisp_Object pos, Lisp_Object prop, Lisp_Object object,
+		     Lisp_Object at_flag, int text_props_only)
+{
+  Bytind position;
+  int invert = 0;
+
+  object = decode_buffer_or_string (object);
+  position = get_buffer_or_string_pos_byte (object, pos, GB_NO_ERROR_IF_BAD);
+  CHECK_SYMBOL (prop);
+
+  /* We canonicalize the start/end-open/closed properties to the
+     non-default version -- "adding" the default property really
+     needs to remove the non-default one.  See below for more
+     on this. */
+  if (EQ (prop, Qstart_closed))
+    {
+      prop = Qstart_open;
+      invert = 1;
+    }
+
+  if (EQ (prop, Qend_open))
+    {
+      prop = Qend_closed;
+      invert = 1;
+    }
+
+  {
+    Lisp_Object val =
+      get_text_property_bytind (position, prop, object,
+				decode_extent_at_flag (at_flag),
+				text_props_only);
+    if (invert)
+      val = NILP (val) ? Qt : Qnil;
+    return val;
+  }
+}
+
+DEFUN ("get-text-property", Fget_text_property, Sget_text_property, 2, 4, 0 /*
+Returns the value of the PROP property at the given position.
+Optional arg OBJECT specifies the buffer or string to look in, and
+ defaults to the current buffer.
+Optional arg AT-FLAG controls what it means for a property to be \"at\"
+ a position, and has the same meaning as in `extent-at'.
+This examines only those properties added with `put-text-property'.
+See also `get-char-property'.
+*/ )
+     (pos, prop, object, at_flag)
+     Lisp_Object pos, prop, object, at_flag;
+{
+  return get_text_property_1 (pos, prop, object, at_flag, 1);
+}
+
+DEFUN ("get-char-property", Fget_char_property, Sget_char_property, 2, 4, 0 /*
+Returns the value of the PROP property at the given position.
+Optional arg OBJECT specifies the buffer or string to look in, and
+ defaults to the current buffer.
+Optional arg AT-FLAG controls what it means for a property to be \"at\"
+ a position, and has the same meaning as in `extent-at'.
+This examines properties on all extents.
+See also `get-text-property'.
+*/ )
+     (pos, prop, object, at_flag)
+     Lisp_Object pos, prop, object, at_flag;
+{
+  return get_text_property_1 (pos, prop, object, at_flag, 0);
+}
+
+/* About start/end-open/closed:
+
+   These properties have to be handled specially because of their
+   strange behavior.  If I put the "start-open" property on a region,
+   then *all* text-property extents in the region have to have their
+   start be open.  This is unlike all other properties, which don't
+   affect the extents of text properties other than their own.
+
+   So:
+
+   1) We have to map start-closed to (not start-open) and end-open
+      to (not end-closed) -- i.e. adding the default is really the
+      same as remove the non-default property.  It won't work, for
+      example, to have both "start-open" and "start-closed" on
+      the same region.
+   2) Whenever we add one of these properties, we go through all
+      text-property extents in the region and set the appropriate
+      open/closedness on them.
+   3) Whenever we change a text-property extent for a property,
+      we have to make sure we set the open/closedness properly.
+
+      (2) and (3) together rely on, and maintain, the invariant
+      that the open/closedness of text-property extents is correct
+      at the beginning and end of each operation.
+   */
+
+struct put_text_prop_arg
+{
+  Lisp_Object prop, value;	/* The property and value we are storing */
+  Bytind start, end;	/* The region into which we are storing it */
+  Lisp_Object object;
+  Lisp_Object the_extent;	/* Our chosen extent; this is used for
+				   communication between subsequent passes. */
+  int changed_p;		/* Output: whether we have modified anything */
+};
+
+static int
+put_text_prop_mapper (EXTENT e, void *arg)
+{
+  struct put_text_prop_arg *closure = (struct put_text_prop_arg *) arg;
+
+  Lisp_Object object = closure->object;
+  Lisp_Object value = closure->value;
+  Bytind e_start, e_end; 
+  Bytind start = closure->start;
+  Bytind end   = closure->end;
+  Lisp_Object extent, e_val;
+  int is_eq;
+
+  XSETEXTENT (extent, e);
+
+  /* Note: in some cases when the property itself is 'start-open
+     or 'end-closed, the checks to set the openness may do a bit
+     of extra work; but it won't hurt because we then fix up the
+     openness later in in put_text_prop_openness_mapper(). */
+  if (!EQ (Fextent_property (extent, Qtext_prop, Qnil), closure->prop))
+    /* It's not for this property; do nothing. */
+    return 0;
+
+  e_start = extent_endpoint_bytind (e, 0);
+  e_end   = extent_endpoint_bytind (e, 1);
+  e_val = Fextent_property (extent, closure->prop, Qnil);
+  is_eq = EQ (value, e_val);
+
+  if (!NILP (value) && NILP (closure->the_extent) && is_eq)
+    {
+      /* We want there to be an extent here at the end, and we haven't picked
+	 one yet, so use this one.  Extend it as necessary.  We only reuse an
+	 extent which has an EQ value for the prop in question to avoid
+	 side-effecting the kill ring (that is, we never change the property
+	 on an extent after it has been created.)
+       */
+      if (e_start != start || e_end != end)
+	{
+	  Bytind new_start = min (e_start, start);
+	  Bytind new_end = max (e_end, end);
+	  set_extent_endpoints (e, new_start, new_end, Qnil);
+	  /* If we changed the endpoint, then we need to set its
+	     openness. */
+	  set_extent_openness (e, new_start != e_start
+			       ? !NILP (get_text_property_bytind
+					(start, Qstart_open, object,
+					 EXTENT_AT_AFTER, 1)) : -1,
+			       new_end != e_end
+			       ? NILP (get_text_property_bytind
+				       (end - 1, Qend_closed, object,
+					EXTENT_AT_AFTER, 1))
+			       : -1);
+	  closure->changed_p = 1;
+	}
+      closure->the_extent = extent;
+    }
+
+  /* Even if we're adding a prop, at this point, we want all other extents of
+     this prop to go away (as now they overlap).  So the theory here is that,
+     when we are adding a prop to a region that has multiple (disjoint)
+     occurences of that prop in it already, we pick one of those and extend
+     it, and remove the others.
+   */
+
+  else if (EQ (extent, closure->the_extent))
+    {
+      /* just in case map-extents hits it again (does that happen?) */
+      ;
+    }
+  else if (e_start >= start && e_end <= end)
+    {
+      /* Extent is contained in region; remove it.  Don't destroy or modify
+	 it, because we don't want to change the attributes pointed to by the
+	 duplicates in the kill ring.
+       */
+      extent_detach (e);
+      closure->changed_p = 1;
+    }
+  else if (!NILP (closure->the_extent) &&
+	   is_eq &&
+	   e_start <= end &&
+	   e_end >= start)
+    {
+      EXTENT te = XEXTENT (closure->the_extent);
+      /* This extent overlaps, and has the same prop/value as the extent we've
+	 decided to reuse, so we can remove this existing extent as well (the
+	 whole thing, even the part outside of the region) and extend
+	 the-extent to cover it, resulting in the minimum number of extents in
+	 the buffer.
+       */
+      Bytind the_start = extent_endpoint_bytind (te, 0);
+      Bytind the_end = extent_endpoint_bytind (te, 1);
+      if (e_start != the_start &&  /* note AND not OR -- hmm, why is this
+				      the case? I think it's because the
+				      assumption that the text-property
+				      extents don't overlap makes it
+				      OK; changing it to an OR would
+				      result in changed_p sometimes getting
+				      falsely marked.  Is this bad? */
+	  e_end   != the_end)
+	{
+	  Bytind new_start = min (e_start, the_start);
+	  Bytind new_end = max (e_end, the_end);
+	  set_extent_endpoints (te, new_start, new_end, Qnil);
+	  /* If we changed the endpoint, then we need to set its
+	     openness.  We are setting the endpoint to be the same as
+	     that of the extent we're about to remove, and we assume
+	     (the invariant mentioned above) that extent has the
+	     proper endpoint setting, so we just use it. */
+	  set_extent_openness (te, new_start != e_start ?
+			       extent_start_open_p (e) : -1,
+			       new_end != e_end ?
+			       extent_end_open_p (e) : -1);
+	  closure->changed_p = 1;
+	}
+      extent_detach (e);
+    }
+  else if (e_end <= end)
+    {
+      /* Extent begins before start but ends before end, so we can just
+	 decrease its end position.
+       */
+      if (e_end != start)
+	{
+	  set_extent_endpoints (e, e_start, start, Qnil);
+	  set_extent_openness (e, -1, NILP (get_text_property_bytind
+				       (start - 1, Qend_closed, object,
+					EXTENT_AT_AFTER, 1)));
+	  closure->changed_p = 1;
+	}
+    }
+  else if (e_start >= start)
+    {
+      /* Extent ends after end but begins after start, so we can just
+	 increase its start position.
+       */
+      if (e_start != end)
+	{
+	  set_extent_endpoints (e, end, e_end, Qnil);
+	  set_extent_openness (e, !NILP (get_text_property_bytind
+					(end, Qstart_open, object,
+					 EXTENT_AT_AFTER, 1)), -1);
+	  closure->changed_p = 1;
+	}
+    }
+  else
+    {
+      /* Otherwise, `extent' straddles the region.  We need to split it.
+       */
+      set_extent_endpoints (e, e_start, start, Qnil);
+      set_extent_openness (e, -1, NILP (get_text_property_bytind
+					(start - 1, Qend_closed, object,
+					 EXTENT_AT_AFTER, 1)));
+      set_extent_openness (copy_extent (e, end, e_end, extent_object (e)),
+			   !NILP (get_text_property_bytind
+				  (end, Qstart_open, object,
+				   EXTENT_AT_AFTER, 1)), -1);
+      closure->changed_p = 1;
+    }
+
+  return 0;  /* to continue mapping. */
+}
+
+static int
+put_text_prop_openness_mapper (EXTENT e, void *arg)
+{
+  struct put_text_prop_arg *closure = (struct put_text_prop_arg *) arg;
+  Bytind e_start, e_end; 
+  Bytind start = closure->start;
+  Bytind end   = closure->end;
+  Lisp_Object extent;
+  XSETEXTENT (extent, e);
+  e_start = extent_endpoint_bytind (e, 0);
+  e_end   = extent_endpoint_bytind (e, 1);
+
+  if (NILP (Fextent_property (extent, Qtext_prop, Qnil)))
+    {
+      /* It's not a text-property extent; do nothing. */
+      ;
+    }
+  /* Note end conditions and NILP/!NILP's carefully. */
+  else if (EQ (closure->prop, Qstart_open)
+	   && e_start >= start && e_start < end)
+    set_extent_openness (e, !NILP (closure->value), -1);
+  else if (EQ (closure->prop, Qend_closed)
+	   && e_end > start && e_end <= end)
+    set_extent_openness (e, -1, NILP (closure->value));
+
+  return 0;  /* to continue mapping. */
+}
+
+static int
+put_text_prop (Bytind start, Bytind end, Lisp_Object object,
+	       Lisp_Object prop, Lisp_Object value,
+	       int duplicable_p)
+{
+  /* This function can GC */
+  struct put_text_prop_arg closure;
+
+  if (start == end)   /* There are no characters in the region. */
+    return 0;
+
+  /* convert to the non-default versions, since a nil property is
+     the same as it not being present. */
+  if (EQ (prop, Qstart_closed))
+    {
+      prop = Qstart_open;
+      value = NILP (value) ? Qt : Qnil;
+    }
+  else if (EQ (prop, Qend_open))
+    {
+      prop = Qend_closed;
+      value = NILP (value) ? Qt : Qnil;
+    }
+
+  value = canonicalize_extent_property (prop, value);
+
+  closure.prop = prop;
+  closure.value = value;
+  closure.start = start;
+  closure.end = end;
+  closure.object = object;
+  closure.changed_p = 0;
+  closure.the_extent = Qnil;
+
+  map_extents_bytind (start, end,
+		      put_text_prop_mapper,
+		      (void *) &closure, object, 0,
+		      /* get all extents that abut the region */
+		      ME_ALL_EXTENTS_CLOSED | ME_END_CLOSED |
+		      /* it might QUIT or error if the user has
+			 fucked with the extent plist. */
+		      ME_MIGHT_THROW |
+		      ME_MIGHT_MODIFY_EXTENTS);
+
+  /* If we made it through the loop without reusing an extent
+     (and we want there to be one) make it now.
+   */
+  if (!NILP (value) && NILP (closure.the_extent))
+    {
+      Lisp_Object extent = Qnil;
+
+      XSETEXTENT (extent, make_extent_internal (object, start, end));
+      closure.changed_p = 1;
+      Fset_extent_property (extent, Qtext_prop, prop);
+      Fset_extent_property (extent, prop, value);
+      if (duplicable_p)
+	{
+	  extent_duplicable_p (XEXTENT (extent)) = 1;
+	  Fset_extent_property (extent, Qpaste_function,
+				Qtext_prop_extent_paste_function);
+	}
+      set_extent_openness (XEXTENT (extent),
+			   !NILP (get_text_property_bytind
+				  (start, Qstart_open, object,
+				   EXTENT_AT_AFTER, 1)),
+			   NILP (get_text_property_bytind
+				 (end - 1, Qend_closed, object,
+				  EXTENT_AT_AFTER, 1)));
+    }
+
+  if (EQ (prop, Qstart_open) || EQ (prop, Qend_closed))
+    {
+      map_extents_bytind (start, end,
+			  put_text_prop_openness_mapper,
+			  (void *) &closure, object, 0,
+			  /* get all extents that abut the region */
+			  ME_ALL_EXTENTS_CLOSED | ME_END_CLOSED |
+			  ME_MIGHT_MODIFY_EXTENTS);
+    }
+
+  return closure.changed_p;
+}
+
+DEFUN ("put-text-property", Fput_text_property, Sput_text_property, 4, 5, 0 /*
+Adds the given property/value to all characters in the specified region.
+The property is conceptually attached to the characters rather than the
+region.  The properties are copied when the characters are copied/pasted.
+Fifth argument OBJECT is the buffer or string containing the text, and
+defaults to the current buffer.
+*/ )
+     (start, end, prop, value, object)
+     Lisp_Object start, end, prop, value, object;
+{
+  /* This function can GC */
+  Bytind s, e;
+
+  object = decode_buffer_or_string (object);
+  get_buffer_or_string_range_byte (object, start, end, &s, &e, 0);
+  CHECK_SYMBOL (prop);
+  put_text_prop (s, e, object, prop, value, 1);
+  return prop;
+}
+
+DEFUN ("put-nonduplicable-text-property", Fput_nonduplicable_text_property,
+       Sput_nonduplicable_text_property, 4, 5, 0 /*
+Adds the given property/value to all characters in the specified region.
+The property is conceptually attached to the characters rather than the
+region, however the properties will not be copied when the characters
+are copied.
+Fifth argument OBJECT is the buffer or string containing the text, and
+defaults to the current buffer.
+*/ )
+     (start, end, prop, value, object)
+     Lisp_Object start, end, prop, value, object;
+{
+  /* This function can GC */
+  Bytind s, e;
+
+  object = decode_buffer_or_string (object);
+  get_buffer_or_string_range_byte (object, start, end, &s, &e, 0);
+  CHECK_SYMBOL (prop);
+  put_text_prop (s, e, object, prop, value, 0);
+  return prop;
+}
+
+DEFUN ("add-text-properties", Fadd_text_properties, Sadd_text_properties,
+       3, 4, 0 /*
+Add properties to the characters from START to END.
+The third argument PROPS is a property list specifying the property values
+to add.  The optional fourth argument, OBJECT, is the buffer or string
+containing the text and defaults to the current buffer.  Returns t if
+any property was changed, nil otherwise.
+*/ )
+	(start, end, props, object)
+	Lisp_Object start, end, props, object;
+{
+  /* This function can GC */
+  int changed = 0;
+  Bytind s, e;
+
+  object = decode_buffer_or_string (object);
+  get_buffer_or_string_range_byte (object, start, end, &s, &e, 0);
+  CHECK_LIST (props);
+  for (; !NILP (props); props = Fcdr (Fcdr (props)))
+    {
+      Lisp_Object prop = XCAR (props);
+      Lisp_Object value = Fcar (XCDR (props));
+      CHECK_SYMBOL (prop);
+      changed |= put_text_prop (s, e, object, prop, value, 1);
+    }
+  return (changed ? Qt : Qnil);
+}
+
+
+DEFUN ("add-nonduplicable-text-properties",
+       Fadd_nonduplicable_text_properties,
+       Sadd_nonduplicable_text_properties,
+       3, 4, 0 /*
+Add nonduplicable properties to the characters from START to END.
+(The properties will not be copied when the characters are copied.)
+The third argument PROPS is a property list specifying the property values
+to add.  The optional fourth argument, OBJECT, is the buffer or string
+containing the text and defaults to the current buffer.  Returns t if
+any property was changed, nil otherwise.
+*/ )
+	(start, end, props, object)
+	Lisp_Object start, end, props, object;
+{
+  /* This function can GC */
+  int changed = 0;
+  Bytind s, e;
+
+  object = decode_buffer_or_string (object);
+  get_buffer_or_string_range_byte (object, start, end, &s, &e, 0);
+  CHECK_LIST (props);
+  for (; !NILP (props); props = Fcdr (Fcdr (props)))
+    {
+      Lisp_Object prop = XCAR (props);
+      Lisp_Object value = Fcar (XCDR (props));
+      CHECK_SYMBOL (prop);
+      changed |= put_text_prop (s, e, object, prop, value, 0);
+    }
+  return (changed ? Qt : Qnil);
+}
+
+DEFUN ("remove-text-properties", Fremove_text_properties,
+       Sremove_text_properties, 3, 4, 0 /*
+Remove the given properties from all characters in the specified region.
+PROPS should be a plist, but the values in that plist are ignored (treated
+as nil).  Returns t if any property was changed, nil otherwise.
+Fourth argument OBJECT is the buffer or string containing the text, and
+defaults to the current buffer.
+*/ )
+	(start, end, props, object)
+	Lisp_Object start, end, props, object;
+{
+  /* This function can GC */
+  int changed = 0;
+  Bytind s, e;
+
+  object = decode_buffer_or_string (object);
+  get_buffer_or_string_range_byte (object, start, end, &s, &e, 0);
+  CHECK_LIST (props);
+  for (; !NILP (props); props = Fcdr (Fcdr (props)))
+    {
+      Lisp_Object prop = XCAR (props);
+      CHECK_SYMBOL (prop);
+      changed |= put_text_prop (s, e, object, prop, Qnil, 1);
+    }
+  return (changed ? Qt : Qnil);
+}
+
+/* Whenever a text-prop extent is pasted into a buffer (via `yank' or `insert'
+   or whatever) we attach the properties to the buffer by calling
+   `put-text-property' instead of by simply allowing the extent to be copied or
+   re-attached.  Then we return nil, telling the extents code not to attach it
+   again.  By handing the insertion hackery in this way, we make kill/yank
+   behave consistently with put-text-property and not fragment the extents
+   (since text-prop extents must partition, not overlap).
+
+   The lisp implementation of this was probably fast enough, but since I moved
+   the rest of the put-text-prop code here, I moved this as well for 
+   completeness. 
+ */
+DEFUN ("text-prop-extent-paste-function", Ftext_prop_extent_paste_function,
+       Stext_prop_extent_paste_function, 3, 3, 0 /*
+Used as the `paste-function' property of `text-prop' extents.
+*/ )
+     (extent, from, to)
+     Lisp_Object extent, from, to;
+{
+  /* This function can GC */
+  Lisp_Object prop, val;
+
+  prop = Fextent_property (extent, Qtext_prop, Qnil);
+  if (NILP (prop))
+    signal_simple_error ("internal error: no text-prop", extent);
+  val = Fextent_property (extent, prop, Qnil);
+  if (NILP (val))
+    signal_simple_error_2 ("internal error: no text-prop",
+			   extent, prop);
+  Fput_text_property (from, to, prop, val, Qnil);
+  return Qnil; /* important! */
+}
+
+/* This function could easily be written in Lisp but the C code wants
+   to use it in connection with invisible extents (at least currently).
+   If this changes, consider moving this back into Lisp. */
+
+DEFUN ("next-single-property-change", Fnext_single_property_change,
+       Snext_single_property_change, 2, 4, 0 /*
+Return the position of next property change for a specific property.
+Scans characters forward from POS till it finds a change in the PROP
+ property, then returns the position of the change.  The optional third
+ argument OBJECT is the buffer or string to scan (defaults to the current
+ buffer).
+The property values are compared with `eq'.
+Return nil if the property is constant all the way to the end of BUFFER.
+If the value is non-nil, it is a position greater than POS, never equal.
+
+If the optional fourth argument LIMIT is non-nil, don't search
+ past position LIMIT; return LIMIT if nothing is found before LIMIT.
+If two or more extents with conflicting non-nil values for PROP overlap
+ a particular character, it is undefined which value is considered to be
+ the value of PROP. (Note that this situation will not happen if you always
+ use the text-property primitives.)
+*/ )
+  (pos, prop, object, limit)
+     Lisp_Object pos, prop, object, limit;
+{
+  Bufpos bpos;
+  Bufpos blim;
+  Lisp_Object extent, value;
+  int limit_was_nil;
+
+  object = decode_buffer_or_string (object);
+  bpos = get_buffer_or_string_pos_char (object, pos, 0);
+  if (NILP (limit))
+    {
+      blim = buffer_or_string_accessible_end_char (object);
+      limit_was_nil = 1;
+    }
+  else
+    {
+      blim = get_buffer_or_string_pos_char (object, limit, 0);
+      limit_was_nil = 0;
+    }
+  CHECK_SYMBOL (prop);
+
+  extent = Fextent_at (make_int (bpos), object, prop, Qnil, Qnil);
+  if (!NILP (extent))
+    value = Fextent_property (extent, prop, Qnil);
+  else
+    value = Qnil;
+
+  while (1)
+    {
+      bpos = XINT (Fnext_extent_change (make_int (bpos), object));
+      if (bpos >= blim)
+	break; /* property is the same all the way to the end */
+      extent = Fextent_at (make_int (bpos), object, prop, Qnil, Qnil);
+      if ((NILP (extent) && !NILP (value)) ||
+	  (!NILP (extent) && !EQ (value,
+				  Fextent_property (extent, prop, Qnil))))
+	return make_int (bpos);
+    }
+
+  /* I think it's more sensible for this function to return nil always
+     in this situation and it used to do it this way, but it's been changed
+     for FSF compatibility. */
+  if (limit_was_nil)
+    return Qnil;
+  else
+    return make_int (blim);
+}
+
+/* See comment on previous function about why this is written in C. */
+
+DEFUN ("previous-single-property-change", Fprevious_single_property_change,
+       Sprevious_single_property_change, 2, 4, 0 /*
+Return the position of next property change for a specific property.
+Scans characters backward from POS till it finds a change in the PROP
+ property, then returns the position of the change.  The optional third
+ argument OBJECT is the buffer or string to scan (defaults to the current
+ buffer).
+The property values are compared with `eq'.
+Return nil if the property is constant all the way to the start of BUFFER.
+If the value is non-nil, it is a position less than POS, never equal.
+
+If the optional fourth argument LIMIT is non-nil, don't search back
+ past position LIMIT; return LIMIT if nothing is found until LIMIT.
+If two or more extents with conflicting non-nil values for PROP overlap
+ a particular character, it is undefined which value is considered to be
+ the value of PROP. (Note that this situation will not happen if you always
+ use the text-property primitives.)
+*/ )
+  (pos, prop, object, limit)
+     Lisp_Object pos, prop, object, limit;
+{
+  Bufpos bpos;
+  Bufpos blim;
+  Lisp_Object extent, value;
+  int limit_was_nil;
+
+  object = decode_buffer_or_string (object);
+  bpos = get_buffer_or_string_pos_char (object, pos, 0);
+  if (NILP (limit))
+    {
+      blim = buffer_or_string_accessible_begin_char (object);
+      limit_was_nil = 1;
+    }
+  else
+    {
+      blim = get_buffer_or_string_pos_char (object, limit, 0);
+      limit_was_nil = 0;
+    }
+
+  CHECK_SYMBOL (prop);
+
+  /* extent-at refers to the character AFTER bpos, but we want the
+     character before bpos.  Thus the - 1.  extent-at simply
+     returns nil on bogus positions, so not to worry. */
+  extent = Fextent_at (make_int (bpos - 1), object, prop, Qnil, Qnil);
+  if (!NILP (extent))
+    value = Fextent_property (extent, prop, Qnil);
+  else
+    value = Qnil;
+
+  while (1)
+    {
+      bpos = XINT (Fprevious_extent_change (make_int (bpos), object));
+      if (bpos <= blim)
+	break; /* property is the same all the way to the beginning */
+      extent = Fextent_at (make_int (bpos - 1), object, prop, Qnil, Qnil);
+      if ((NILP (extent) && !NILP (value)) ||
+	  (!NILP (extent) && !EQ (value,
+				  Fextent_property (extent, prop, Qnil))))
+	return make_int (bpos);
+    }
+  
+  /* I think it's more sensible for this function to return nil always
+     in this situation and it used to do it this way, but it's been changed
+     for FSF compatibility. */
+  if (limit_was_nil)
+    return Qnil;
+  else
+    return make_int (blim);
+}
+
+#ifdef MEMORY_USAGE_STATS
+
+int
+compute_buffer_extent_usage (struct buffer *b, struct overhead_stats *ovstats)
+{
+  /* #### not yet written */
+  return 0;
+}
+
+#endif /* MEMORY_USAGE_STATS */
+
+
+/************************************************************************/
+/*				initialization				*/
+/************************************************************************/
+
+void
+syms_of_extents (void)
+{
+  defsymbol (&Qextentp, "extentp");
+  defsymbol (&Qextent_live_p, "extent-live-p");
+
+  defsymbol (&Qend_closed, "end-closed");
+  defsymbol (&Qstart_open, "start-open");
+  defsymbol (&Qall_extents_closed, "all-extents-closed");
+  defsymbol (&Qall_extents_open, "all-extents-open");
+  defsymbol (&Qall_extents_closed_open, "all-extents-closed-open");
+  defsymbol (&Qall_extents_open_closed, "all-extents-open-closed");
+  defsymbol (&Qstart_in_region, "start-in-region");
+  defsymbol (&Qend_in_region, "end-in-region");
+  defsymbol (&Qstart_and_end_in_region, "start-and-end-in-region");
+  defsymbol (&Qstart_or_end_in_region, "start-or-end-in-region");
+  defsymbol (&Qnegate_in_region, "negate-in-region");
+
+  defsymbol (&Qdetached, "detached");
+  defsymbol (&Qdestroyed, "destroyed");
+  defsymbol (&Qbegin_glyph, "begin-glyph");
+  defsymbol (&Qend_glyph, "end-glyph");
+  defsymbol (&Qstart_open, "start-open");
+  defsymbol (&Qend_open, "end-open");
+  defsymbol (&Qstart_closed, "start-closed");
+  defsymbol (&Qend_closed, "end-closed");
+  defsymbol (&Qread_only, "read-only");
+  /* defsymbol (&Qhighlight, "highlight"); in faces.c */
+  defsymbol (&Qunique, "unique");
+  defsymbol (&Qduplicable, "duplicable");
+  defsymbol (&Qreplicating, "replicating");
+  defsymbol (&Qdetachable, "detachable");
+  defsymbol (&Qpriority, "priority");
+  defsymbol (&Qmouse_face, "mouse-face");
+
+  defsymbol (&Qglyph_layout, "glyph-layout");	/* backwards compatibility */
+  defsymbol (&Qbegin_glyph_layout, "begin-glyph-layout");
+  defsymbol (&Qbegin_glyph_layout, "end-glyph-layout");
+  defsymbol (&Qoutside_margin, "outside-margin");
+  defsymbol (&Qinside_margin, "inside-margin");
+  defsymbol (&Qwhitespace, "whitespace");
+  /* Qtext defined in general.c */
+
+  defsymbol (&Qglyph_invisible, "glyph-invisible");
+
+  defsymbol (&Qpaste_function, "paste-function");
+  defsymbol (&Qcopy_function,  "copy-function");
+
+  defsymbol (&Qtext_prop, "text-prop");
+  defsymbol (&Qtext_prop_extent_paste_function,
+	     "text-prop-extent-paste-function");
+
+  defsubr (&Sextentp);
+  defsubr (&Sextent_live_p);
+  defsubr (&Sextent_detached_p);
+  defsubr (&Sextent_start_position);
+  defsubr (&Sextent_end_position);
+  defsubr (&Sextent_object);
+  defsubr (&Sextent_length);
+#if 0
+  defsubr (&Sstack_of_extents);
+#endif
+
+  defsubr (&Smake_extent);
+  defsubr (&Scopy_extent);
+  defsubr (&Sdelete_extent);
+  defsubr (&Sdetach_extent);
+  defsubr (&Sset_extent_endpoints);
+  defsubr (&Snext_extent);
+  defsubr (&Sprevious_extent);
+#if DEBUG_XEMACS
+  defsubr (&Snext_e_extent);
+  defsubr (&Sprevious_e_extent);
+#endif
+  defsubr (&Snext_extent_change);
+  defsubr (&Sprevious_extent_change);
+
+  defsubr (&Sextent_parent);
+  defsubr (&Sextent_children);
+  defsubr (&Sset_extent_parent);
+
+  defsubr (&Sextent_in_region_p);
+  defsubr (&Smap_extents);
+  defsubr (&Smap_extent_children);
+  defsubr (&Sextent_at);
+
+  defsubr (&Sextent_face);
+  defsubr (&Sset_extent_face);
+  defsubr (&Sextent_mouse_face);
+  defsubr (&Sset_extent_mouse_face);
+  defsubr (&Sset_extent_begin_glyph);
+  defsubr (&Sset_extent_end_glyph);
+  defsubr (&Sextent_begin_glyph);
+  defsubr (&Sextent_end_glyph);
+  defsubr (&Sset_extent_begin_glyph_layout);
+  defsubr (&Sset_extent_end_glyph_layout);
+  defsubr (&Sextent_begin_glyph_layout);
+  defsubr (&Sextent_end_glyph_layout);
+  defsubr (&Sset_extent_priority);
+  defsubr (&Sextent_priority);
+  defsubr (&Sset_extent_property);
+  defsubr (&Sextent_property);
+  defsubr (&Sextent_properties);
+
+  defsubr (&Shighlight_extent);
+  defsubr (&Sforce_highlight_extent);
+
+  defsubr (&Sinsert_extent);
+
+  defsubr (&Sget_text_property);
+  defsubr (&Sget_char_property);
+  defsubr (&Sput_text_property);
+  defsubr (&Sput_nonduplicable_text_property);
+  defsubr (&Sadd_text_properties);
+  defsubr (&Sadd_nonduplicable_text_properties);
+  defsubr (&Sremove_text_properties);
+  defsubr (&Stext_prop_extent_paste_function);
+  defsubr (&Snext_single_property_change);
+  defsubr (&Sprevious_single_property_change);
+}
+
+void
+vars_of_extents (void)
+{
+  DEFVAR_INT ("mouse-highlight-priority", &mouse_highlight_priority /*
+The priority to use for the mouse-highlighting pseudo-extent
+that is used to highlight extents with the `mouse-face' attribute set.
+See `set-extent-priority'.
+*/ );
+  /* Set mouse-highlight-priority (which ends up being used both for the
+     mouse-highlighting pseudo-extent and the primary selection extent)
+     to a very high value because very few extents should override it.
+     1000 gives lots of room below it for different-prioritied extents.
+     10 doesn't. ediff, for example, likes to use priorities around 100.
+     --ben */
+  mouse_highlight_priority = /* 10 */ 1000;
+
+  DEFVAR_LISP ("default-text-properties", &Vdefault_text_properties /*
+Property list giving default values for text properties.
+Whenever a character does not specify a value for a property, the value
+stored in this list is used instead.  This only applies when the
+functions `get-text-property' or `get-char-property' are called.
+*/ );
+  Vdefault_text_properties = Qnil;
+
+  staticpro (&Vlast_highlighted_extent);
+  Vlast_highlighted_extent = Qnil;
+
+  Vextent_face_reusable_list = Fcons (Qnil, Qnil);
+  staticpro (&Vextent_face_reusable_list);
+
+  extent_auxiliary_defaults.begin_glyph = Qnil;
+  extent_auxiliary_defaults.end_glyph = Qnil;
+  extent_auxiliary_defaults.parent = Qnil;
+  extent_auxiliary_defaults.children = Qnil;
+  extent_auxiliary_defaults.priority = 0;
+  extent_auxiliary_defaults.invisible = Qnil;
+  extent_auxiliary_defaults.read_only = Qnil;
+  extent_auxiliary_defaults.mouse_face = Qnil;
+}
+
+void
+complex_vars_of_extents (void)
+{
+  staticpro (&Vextent_face_memoize_hash_table);
+  /* The memoize hash-table maps from lists of symbols to lists of
+     faces.  It needs to be `equal' to implement the memoization.
+     The reverse table maps in the other direction and just needs
+     to do `eq' comparison because the lists of faces are already
+     memoized. */
+  Vextent_face_memoize_hash_table =
+    make_lisp_hashtable (100, HASHTABLE_VALUE_WEAK, HASHTABLE_EQUAL);
+  staticpro (&Vextent_face_reverse_memoize_hash_table);
+  Vextent_face_reverse_memoize_hash_table =
+    make_lisp_hashtable (100, HASHTABLE_KEY_WEAK, HASHTABLE_EQ);
+}