Make ghostel-yank-pop fall through to completing-read

When M-y is pressed without a preceding yank, instead of signaling
an error, open a completing-read browser over kill-ring and paste
the selected entry. This integrates naturally with consult/vertico.

Author: dakra

ghostel.el

@@ -1108,21 +1108,26 @@ Use `ghostel-yank-pop' afterwards to cycle through older kills."
 
 (defun ghostel-yank-pop ()
   "Replace the just-yanked text with the next kill ring entry.
-Must be called after `ghostel-yank' or `ghostel-yank-pop'.
-Sends backspaces to erase the previous yank, then pastes the next entry."
+After `ghostel-yank' or `ghostel-yank-pop', cycles through the
+kill ring by erasing the previous paste and inserting the next entry.
+Otherwise, opens a `completing-read' browser over `kill-ring' and
+pastes the selected entry into the terminal."
   (interactive)
-  (unless (memq last-command '(ghostel-yank ghostel-yank-pop))
-    (user-error "Previous command was not a yank"))
-  (let* ((prev-text (current-kill ghostel--yank-index t))
-         (prev-len (length prev-text)))
-    (setq ghostel--yank-index (1+ ghostel--yank-index))
-    ;; Erase previous paste: send backspaces
-    (when (and ghostel--process (process-live-p ghostel--process))
-      (process-send-string ghostel--process
-                           (make-string prev-len ?\x7f)))
-    ;; Paste the next entry
-    (ghostel--paste-text (current-kill ghostel--yank-index t))
-    (setq this-command 'ghostel-yank-pop)))
+  (if (memq last-command '(ghostel-yank ghostel-yank-pop))
+      (let* ((prev-text (current-kill ghostel--yank-index t))
+             (prev-len (length prev-text)))
+        (setq ghostel--yank-index (1+ ghostel--yank-index))
+        ;; Erase previous paste: send backspaces
+        (when (and ghostel--process (process-live-p ghostel--process))
+          (process-send-string ghostel--process
+                               (make-string prev-len ?\x7f)))
+        ;; Paste the next entry
+        (ghostel--paste-text (current-kill ghostel--yank-index t))
+        (setq this-command 'ghostel-yank-pop))
+    ;; No preceding yank: browse kill ring and paste selection
+    (when-let* ((text (completing-read "Paste from kill ring: "
+                                       kill-ring nil t)))
+      (ghostel--paste-text text))))
 
 
 ;;; Drag and drop

test/ghostel-test.el

@@ -2608,6 +2608,42 @@ buffer and hand nil to the native module."
   ;; M-y should be bound to ghostel-yank-pop, not send-event
   (should (eq (lookup-key ghostel-mode-map (kbd "M-y")) #'ghostel-yank-pop)))
 
+;; -----------------------------------------------------------------------
+;; Test: ghostel-yank-pop DWIM
+;; -----------------------------------------------------------------------
+
+(ert-deftest ghostel-test-yank-pop-after-yank ()
+  "yank-pop after yank should cycle the kill ring."
+  (let* ((pasted nil)
+         (erased nil)
+         (kill-ring '("first" "second" "third"))
+         (kill-ring-yank-pointer kill-ring)
+         (ghostel--yank-index 0)
+         (last-command 'ghostel-yank)
+         (ghostel--process (start-process "true" nil "true")))
+    (cl-letf (((symbol-function 'ghostel--paste-text)
+               (lambda (text) (push text pasted)))
+              ((symbol-function 'process-live-p) (lambda (_) t))
+              ((symbol-function 'process-send-string)
+               (lambda (_proc str) (setq erased str))))
+      (ghostel-yank-pop)
+      ;; Should have erased the previous paste (5 backspaces for "first")
+      (should (= (length erased) 5))
+      ;; Should have pasted the next kill ring entry
+      (should (equal (car pasted) "second")))))
+
+(ert-deftest ghostel-test-yank-pop-no-preceding-yank ()
+  "yank-pop without preceding yank should use completing-read."
+  (let* ((pasted nil)
+         (kill-ring '("alpha" "beta"))
+         (last-command 'ghostel--self-insert))
+    (cl-letf (((symbol-function 'ghostel--paste-text)
+               (lambda (text) (push text pasted)))
+              ((symbol-function 'completing-read)
+               (lambda (_prompt coll &rest _) (car coll))))
+      (ghostel-yank-pop)
+      (should (equal (car pasted) "alpha")))))
+
 ;; -----------------------------------------------------------------------
 ;; Test: ghostel-copy-mode-recenter
 ;; -----------------------------------------------------------------------
@@ -3076,6 +3112,8 @@ while :; do sleep 0.1; done'\n")
     ghostel-test-c-g-exits-copy-mode
     ghostel-test-inhibit-quit
     ghostel-test-meta-key-bindings
+    ghostel-test-yank-pop-after-yank
+    ghostel-test-yank-pop-no-preceding-yank
     ghostel-test-copy-mode-recenter
     ghostel-test-send-next-key-control-x
     ghostel-test-send-next-key-control-h