Smart yanking for Emacs. See http://mbork.pl/2018-07-02_Smart_yanking for details.

smart-yank.el

(defun has-space-at-boundary-p (string)
  "Check whether STRING has any whitespace on the boundary.
Return 'left, 'right, 'both or nil."
  (let ((result nil))
    (when (string-match-p "^[[:space:]]+" string)
      (setq result 'left))
    (when (string-match-p "[[:space:]]+$" string)
      (if (eq result 'left)
	  (setq result 'both)
	(setq result 'right)))
    result))

(defun is-there-space-around-point-p ()
  "Check whether there is whitespace around point.
Return 'left, 'right, 'both or nil."
  (let ((result nil))
    (when (< (save-excursion
               (skip-chars-backward "[:space:]"))
             0)
      (setq result 'left))
    (when (> (save-excursion
               (skip-chars-forward "[:space:]"))
             0)
      (if (eq result 'left)
	  (setq result 'both)
	(setq result 'right)))
    result))

(defun set-point-before-yanking (string)
  "Put point in the appropriate place before yanking STRING."
  (let ((space-in-yanked-string (has-space-at-boundary-p string))
	(space-at-point (is-there-space-around-point-p)))
    (cond ((and (eq space-in-yanked-string 'left)
		(eq space-at-point 'left))
	   (skip-chars-backward "[:space:]"))
	  ((and (eq space-in-yanked-string 'right)
		(eq space-at-point 'right))
	   (skip-chars-forward "[:space:]")))))

(defun set-point-before-yanking-if-in-text-mode (string)
  "Invoke `set-point-before-yanking' in text modes."
  (when (derived-mode-p 'text-mode)
    (set-point-before-yanking string)))

(advice-add
 'insert-for-yank
 :before
 #'set-point-before-yanking-if-in-text-mode)