* lisp/isearch.el (isearch-forward-thing-at-point): New command (bug#39512).

(search-map): Bind "M-s M-." to isearch-forward-thing-at-point.
(isearch-forward-thing-at-point): New defcustom.

2 files changed, 49 insertions, 5 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 1fe49bbbd6a..559ffd6d8f6 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -958,6 +958,13 @@ authentication mechanism by setting a value for the key 'smtp-auth'.
 
 ** Search and Replace
 
+*** New key 'M-s M-.' starts isearch with the thing found at point.
+This key is bound to the new command 'isearch-forward-thing-at-point'.
+The new user option 'isearch-forward-thing-at-point' defines
+a list of symbols to try to get the "thing" at point.  By default,
+the first element of the list is 'region' that tries to yank
+the currently active region to the search string.
+
 *** New user option 'isearch-wrap-pause' defines how to wrap the search.
 There are choices to disable wrapping completely and to wrap immediately.
 When wrapping immediately, it consistently handles the numeric arguments
diff --git a/lisp/isearch.el b/lisp/isearch.el
index fb2633dbe8b..f1c61fc1677 100644
--- a/lisp/isearch.el
+++ b/lisp/isearch.el
@@ -972,12 +972,13 @@ Each element is an `isearch--state' struct where the slots are
 (defvar-local isearch-mode nil) ;; Name of the minor mode, if non-nil.
 
 (define-key global-map "\C-s" 'isearch-forward)
-(define-key esc-map "\C-s" 'isearch-forward-regexp)
+(define-key esc-map    "\C-s" 'isearch-forward-regexp)
 (define-key global-map "\C-r" 'isearch-backward)
-(define-key esc-map "\C-r" 'isearch-backward-regexp)
-(define-key search-map "w" 'isearch-forward-word)
-(define-key search-map "_" 'isearch-forward-symbol)
-(define-key search-map "." 'isearch-forward-symbol-at-point)
+(define-key esc-map    "\C-r" 'isearch-backward-regexp)
+(define-key search-map    "w" 'isearch-forward-word)
+(define-key search-map    "_" 'isearch-forward-symbol)
+(define-key search-map    "." 'isearch-forward-symbol-at-point)
+(define-key search-map "\M-." 'isearch-forward-thing-at-point)
 
 ;; Entry points to isearch-mode.
 
@@ -1157,6 +1158,42 @@ positive, or search for ARGth symbol backward if ARG is negative."
       (isearch-push-state)
       (isearch-update)))))
 
+(defcustom isearch-forward-thing-at-point '(region url symbol sexp)
+  "A list of symbols to try to get the \"thing\" at point.
+Each element of the list should be one of the symbols supported by
+`bounds-of-thing-at-point'.  This variable is used by the command
+`isearch-forward-thing-at-point' to yank the initial \"thing\"
+as text to the search string."
+  :type '(repeat (symbol :tag "Thing symbol"))
+  :version "28.1")
+
+(defun isearch-forward-thing-at-point ()
+  "Do incremental search forward for the \"thing\" found near point.
+Like ordinary incremental search except that the \"thing\" found at point
+is added to the search string initially.  The \"thing\" is defined by
+`bounds-of-thing-at-point'.  You can customize the variable
+`isearch-forward-thing-at-point' to define a list of symbols to try
+to find a \"thing\" at point.  For example, when the list contains
+the symbol `region' and the region is active, then text from the
+active region is added to the search string."
+  (interactive)
+  (isearch-forward nil 1)
+  (let ((bounds (seq-some (lambda (thing)
+                            (bounds-of-thing-at-point thing))
+                          isearch-forward-thing-at-point)))
+    (cond
+     (bounds
+      (when (use-region-p)
+        (deactivate-mark))
+      (when (< (car bounds) (point))
+	(goto-char (car bounds)))
+      (isearch-yank-string
+       (buffer-substring-no-properties (car bounds) (cdr bounds))))
+     (t
+      (setq isearch-error "No thing at point")
+      (isearch-push-state)
+      (isearch-update)))))
+
 
 ;; isearch-mode only sets up incremental search for the minor mode.
 ;; All the work is done by the isearch-mode commands.