Add command to replace buffer contents

Add a new command 'replace-buffer-contents' that uses the Myers diff
algorithm to non-destructively replace the accessible portion of the
current buffer.  The Myers algorithm is implemented in Gnulib.

* src/editfns.c (Freplace_buffer_contents): New command.
(set_bit, bit_is_set, buffer_chars_equal): New helper functions.
(syms_of_editfns): Define new command.

* test/src/editfns-tests.el (replace-buffer-contents-1)
(replace-buffer-contents-2): New unit tests.

* src/buffer.h (BUF_FETCH_CHAR_AS_MULTIBYTE): New helper macro.

* admin/merge-gnulib (GNULIB_MODULES): Add diffseq.h and minmax.h.

1 files changed, 2 insertions, 2 deletions

diff --git a/admin/merge-gnulib b/admin/merge-gnulib
index e5fb0f59fb3..d4bbf17cb3d 100755
--- a/admin/merge-gnulib
+++ b/admin/merge-gnulib
@@ -30,12 +30,12 @@ GNULIB_MODULES='
   careadlinkat close-stream
   count-leading-zeros count-one-bits count-trailing-zeros
   crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512
-  dtoastr dtotimespec dup2 environ execinfo faccessat
+  diffseq dtoastr dtotimespec dup2 environ execinfo faccessat
   fcntl fcntl-h fdatasync fdopendir
   filemode filevercmp flexmember fstatat fsync
   getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog
   ignore-value intprops largefile lstat
-  manywarnings memrchr mkostemp mktime
+  manywarnings memrchr minmax mkostemp mktime
   pipe2 pselect pthread_sigmask putenv qcopy-acl readlink readlinkat
   sig2str socklen stat-time std-gnu11 stdalign stddef stdio
   stpcpy strftime strtoimax symlink sys_stat