Rework history Isearch for Eshell

This is to make history Isearch for Eshell similar to that of
'comint-mode', by hooking into Isearch properly instead of
defining new commands to emulate Isearch (bug#74287).

* lisp/eshell/em-hist.el (eshell-history-isearch): New user
option.
(eshell-goto-history, eshell--isearch-setup)
(eshell-history-isearch-end, eshell-history-isearch-search)
(eshell-history-isearch-message, eshell-history-isearch-wrap)
(eshell-history-isearch-push-state): New functions.
(eshell-isearch-backward-regexp, eshell-isearch-forward-regexp):
New commands.
(eshell--history-isearch-message-overlay)
(eshell--stored-incomplete-input, eshell--force-history-isearch):
New internal variables.
(eshell-hist-mode-map): Bind 'M-r' to
'eshell-isearch-backward-regexp' and free 'M-s' binding for
normal in-buffer search commands.
(eshell-isearch-backward, eshell-isearch-forward): Use the new
way to start searching.
(eshell-hist-initialize): Use the new Isearch setup function.
(eshell-previous-matching-input): Use 'eshell-goto-history'.
Also inhibit messages when searching.
(eshell-isearch-map, eshell-isearch-repeat-backward)
(eshell-isearch-abort, eshell-isearch-delete-char)
(eshell-isearch-return, eshell-isearch-cancel)
(eshell-isearch-repeat-forward, eshell-test-imatch)
(eshell-return-to-prompt, eshell-prepare-for-search): Remove.
These are for the old history Isearch implementation.

* doc/misc/eshell.texi (History): Document changes.

* etc/NEWS: Annouce changes.

1 files changed, 12 insertions, 3 deletions

diff --git a/doc/misc/eshell.texi b/doc/misc/eshell.texi
index 709417a7efb..264bb655e5e 100644
--- a/doc/misc/eshell.texi
+++ b/doc/misc/eshell.texi
@@ -2660,10 +2660,10 @@ navigation and searching are bound to different keys:
 
 @table @kbd
 @kindex M-r
-@kindex M-s
 @item M-r
-@itemx M-s
-History I-search.
+History I-search.  @kbd{M-r} starts an incremental search in input
+history.  While searching, type @kbd{C-r} to move to the previous match,
+and @kbd{C-s} to move to the next match in the input history.
 
 @kindex M-p
 @kindex M-n
@@ -2674,6 +2674,15 @@ line when you run these commands, they will instead jump to the
 previous or next line that begins with that string.
 @end table
 
+@vindex eshell-history-isearch
+If you would like to use the default Isearch key-bindings to search
+through input history, you may customize @code{eshell-history-isearch}
+to @code{t}.  That makes, for example, @kbd{C-r} and @kbd{C-M-r} in an
+Eshell buffer search in input history only.  In addition, if the value
+of @code{eshell-history-isearch} is @code{dwim}, those commands search
+in the history when the point is after the last prompt, and search in
+the buffer when the point is before or within the last prompt.
+
 @node Extension modules
 @chapter Extension modules
 Eshell provides a facility for defining extension modules so that they