diff options
Diffstat (limited to 'lisp')
| -rw-r--r-- | lisp/subr.el | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/lisp/subr.el b/lisp/subr.el index 63951b92bb2..45bcccbb6e5 100644 --- a/lisp/subr.el +++ b/lisp/subr.el @@ -1996,14 +1996,34 @@ STRING should be given if the last search was by `string-match' on STRING." (buffer-substring-no-properties (match-beginning num) (match-end num))))) -(defun looking-back (regexp &optional limit) +(defun looking-back (regexp &optional limit greedy) "Return non-nil if text before point matches regular expression REGEXP. Like `looking-at' except matches before point, and is slower. LIMIT if non-nil speeds up the search by specifying how far back the -match can start." - (not (null - (save-excursion - (re-search-backward (concat "\\(?:" regexp "\\)\\=") limit t))))) +match can start. + +If GREEDY is non-nil, extend the match backwards as far as possible, +stopping when a single additional previous character cannot be part +of a match for REGEXP." + (let ((start (point)) + (pos + (save-excursion + (and (re-search-backward (concat "\\(?:" regexp "\\)\\=") limit t) + (point))))) + (if (and greedy pos) + (save-restriction + (narrow-to-region (point-min) start) + (while (and (> pos (point-min)) + (save-excursion + (goto-char pos) + (backward-char 1) + (looking-at (concat "\\(?:" regexp "\\)\\'")))) + (setq pos (1- pos))) + (save-excursion + (goto-char pos) + (looking-at (concat "\\(?:" regexp "\\)\\'"))))) + (not (null pos)))) + (defconst split-string-default-separators "[ \f\t\n\r\v]+" "The default value of separators for `split-string'. |