(defun line-matches (regexp)
“Returns non-nil if the current line matches the given regexp, nil otherwise.”
(save-excursion
(beginning-of-line)
(re-search-forward regexp (line-end-position) t)))

Additionally, as this is to be used from elisp and not interactively, I’d opt for using the -p convention for predicates and protecting the match data:

(defun line-matches-p (regexp)
“Return non-nil if the current line matches the given regexp, nil otherwise.”
(save-excursion
(beginning-of-line)
(let ((inhibit-changing-match-data t))
(re-search-forward regexp (line-end-position) t))))

http://www.neilvandyke.org/webjump/