How to set condition for snippet to only expand at beginning of line?

[haqle314]

Hi, I looked through the document but I'm not sure how can I achieve this? Let's say I have a snippet with a single character ?n as key. But I want this snippet to only be active when ?n is at the beginning of the line, not when it's in the middle of the line. I'm trying to write a function to be used as the snippet condition, something like this. But there's no yas--current-key, I tried using yas--current-template but it's not bound during condition checking.

(defun key-at-bol-p ()
    (equal yas--current-key (buffer-substring (line-beginning-position) (point)))))

[npostavs]

Currently expansion conditions are global, not per-snippet. But you could sort of hack it in with yas-key-syntaxes (see below). If #988 is implemented, an alternative would be to use ^n as the snippet key.

(defconst my-yas-bol-keys-regexp
  (regexp-opt '("n")))

(defun my-yas-key-syntax-wrapper (orig-method pos)
  (let ((ret (cond ((stringp orig-method)
                    (skip-syntax-backward orig-method)
                    nil)
                   ((functionp orig-method)
                    (funcall orig-method original))
                   (t (error "Bad `yas-key-syntax' method: `%s'"
                             orig-method)))))
    (if (and (not (bolp))
             (looking-at my-yas-bol-keys-regexp)
             (= (match-end 0) pos))
        ;; Don't match anything else.
        (progn (goto-char pos)
               nil)
      ret)))

(setq yas-key-syntaxes
      (mapcar (lambda (method)
                (apply-partially #'my-yas-key-syntax-wrapper method))
              ;; Default value.
              (list #'yas-try-key-from-whitespace
                    "w_.()" "w_." "w_" "w")))