半角文字で全角文字をisearch

emacs-w3mを使っている時等、たまに全角のアルファベット・数字が出て来る。そんな場合に半角文字でisearchを行ってもsearch結果に出て来なくてちょっと困っていたので、elispを書いてみた。

;;; begin
(defconst *zenkaku-list*
'((?a . ?ａ) (?b . ?ｂ) (?c . ?ｃ) (?d . ?ｄ)
  (?e . ?ｅ) (?f . ?ｆ) (?g . ?ｇ) (?h . ?ｈ)
  (?i . ?ｉ) (?j . ?ｊ) (?k . ?ｋ) (?l . ?ｌ)
  (?m . ?ｍ) (?n . ?ｎ) (?o . ?ｏ) (?p . ?ｐ)
  (?q . ?ｑ) (?r . ?ｒ) (?s . ?ｓ) (?t . ?ｔ)
  (?u . ?ｕ) (?v . ?ｖ) (?w . ?ｗ) (?x . ?ｘ)
  (?y . ?ｙ) (?z . ?ｚ)
  (?A . ?Ａ) (?B . ?Ｂ) (?C . ?Ｃ) (?D . ?Ｄ)
  (?E . ?Ｅ) (?F . ?Ｆ) (?G . ?Ｇ) (?H . ?Ｈ)
  (?I . ?Ｉ) (?J . ?Ｊ) (?K . ?Ｋ) (?L . ?Ｌ)
  (?M . ?Ｍ) (?N . ?Ｎ) (?O . ?Ｏ) (?P . ?Ｐ)
  (?Q . ?Ｑ) (?R . ?Ｒ) (?S . ?Ｓ) (?T . ?Ｔ)
  (?U . ?Ｕ) (?V . ?Ｖ) (?W . ?Ｗ) (?X . ?Ｘ)
  (?Y . ?Ｙ) (?Z . ?Ｚ)
  (?0 . ?０) (?1 . ?１) (?2 . ?２) (?3 . ?３)
  (?4 . ?４) (?5 . ?５) (?6 . ?６) (?7 . ?７)
  (?8 . ?８) (?9 . ?９)))

(defun my-get-hankaku-zenkaku-regexp (target-string)
(let ((case-fold-search nil)
      (target-string-length (length target-string))
      (target-string-new "")
      char-current
      matchp
      (x 0))
  (while (< x target-string-length)
    (setq char-current (elt target-string x))
    (setq matchp nil)
    (dolist (pair *zenkaku-list*)
      (if (char-equal (car pair) char-current)
          (progn
            (setq target-string-new
              (format "%s\\(%s\\|%s\\)"
                target-string-new (string char-current) (string (cdr pair))))
            (setq matchp t))))
    (if (not matchp)
        (setq target-string-new (format "%s%s" target-string-new (string char-current))))
    (setq x (1+ x)))
  target-string-new))

(defun my-re-search-zenkaku-by-hankaku-forward (search-string &optional bound noerror count)
(re-search-forward (my-get-hankaku-zenkaku-regexp search-string) bound noerror count))

(defun my-re-search-zenkaku-by-hankaku-backward (search-string &optional bound noerror count)
(re-search-backward (my-get-hankaku-zenkaku-regexp search-string) bound noerror count))

(defun my-isearch-zenkaku-by-hankaku ()
(if isearch-forward 'my-re-search-zenkaku-by-hankaku-forward 'my-re-search-zenkaku-by-hankaku-backward))

(setq isearch-search-fun-function 'my-isearch-zenkaku-by-hankaku)

;;; end