+(defvar mime-field-decoder-alist nil)
+
+(defvar mime-field-decoder-cache nil)
+
+(defvar mime-update-field-decoder-cache 'mime-update-field-decoder-cache
+ "*Field decoder cache update function.")
+
+;;;###autoload
+(defun mime-set-field-decoder (field &rest specs)
+ "Set decoder of FIELD.
+SPECS must be like `MODE1 DECODER1 MODE2 DECODER2 ...'.
+Each mode must be `nil', `plain', `wide', `summary' or `nov'.
+If mode is `nil', corresponding decoder is set up for every modes."
+ (when specs
+ (let ((mode (pop specs))
+ (function (pop specs)))
+ (if mode
+ (progn
+ (let ((cell (assq mode mime-field-decoder-alist)))
+ (if cell
+ (setcdr cell (put-alist field function (cdr cell)))
+ (setq mime-field-decoder-alist
+ (cons (cons mode (list (cons field function)))
+ mime-field-decoder-alist))
+ ))
+ (apply (function mime-set-field-decoder) field specs)
+ )
+ (mime-set-field-decoder field
+ 'plain function
+ 'wide function
+ 'summary function
+ 'nov function)
+ ))))
+
+;;;###autoload
+(defmacro mime-find-field-presentation-method (name)
+ "Return field-presentation-method from NAME.
+NAME must be `plain', `wide', `summary' or `nov'."
+ (cond ((eq name nil)
+ `(or (assq 'summary mime-field-decoder-cache)
+ '(summary))
+ )
+ ((and (consp name)
+ (car name)
+ (consp (cdr name))
+ (symbolp (car (cdr name)))
+ (null (cdr (cdr name))))
+ `(or (assq ,name mime-field-decoder-cache)
+ (cons ,name nil))
+ )
+ (t
+ `(or (assq (or ,name 'summary) mime-field-decoder-cache)
+ (cons (or ,name 'summary) nil))
+ )))
+
+(defun mime-find-field-decoder-internal (field &optional mode)
+ "Return function to decode field-body of FIELD in MODE.
+Optional argument MODE must be object of field-presentation-method."
+ (cdr (or (assq field (cdr mode))
+ (prog1
+ (funcall mime-update-field-decoder-cache
+ field (car mode))
+ (setcdr mode
+ (cdr (assq (car mode) mime-field-decoder-cache)))
+ ))))
+
+;;;###autoload
+(defun mime-find-field-decoder (field &optional mode)
+ "Return function to decode field-body of FIELD in MODE.
+Optional argument MODE must be object or name of
+field-presentation-method. Name of field-presentation-method must be
+`plain', `wide', `summary' or `nov'.
+Default value of MODE is `summary'."
+ (if (symbolp mode)
+ (let ((p (cdr (mime-find-field-presentation-method mode))))
+ (if (and p (setq p (assq field p)))
+ (cdr p)
+ (cdr (funcall mime-update-field-decoder-cache
+ field (or mode 'summary)))))
+ (inline (mime-find-field-decoder-internal field mode))
+ ))
+
+;;;###autoload
+(defun mime-update-field-decoder-cache (field mode &optional function)
+ "Update field decoder cache `mime-field-decoder-cache'."
+ (cond ((eq function 'identity)
+ (setq function nil)
+ )
+ ((null function)
+ (let ((decoder-alist
+ (cdr (assq (or mode 'summary) mime-field-decoder-alist))))
+ (setq function (cdr (or (assq field decoder-alist)
+ (assq t decoder-alist)))))
+ ))
+ (let ((cell (assq mode mime-field-decoder-cache))
+ ret)
+ (if cell
+ (if (setq ret (assq field (cdr cell)))
+ (setcdr ret function)
+ (setcdr cell (cons (setq ret (cons field function)) (cdr cell))))
+ (setq mime-field-decoder-cache
+ (cons (cons mode (list (setq ret (cons field function))))
+ mime-field-decoder-cache)))
+ ret))
+
+;; ignored fields
+(mime-set-field-decoder 'Archive nil nil)
+(mime-set-field-decoder 'Content-Md5 nil nil)
+(mime-set-field-decoder 'Control nil nil)
+(mime-set-field-decoder 'Date nil nil)
+(mime-set-field-decoder 'Distribution nil nil)
+(mime-set-field-decoder 'Followup-Host nil nil)
+(mime-set-field-decoder 'Followup-To nil nil)
+(mime-set-field-decoder 'Lines nil nil)
+(mime-set-field-decoder 'Message-Id nil nil)
+(mime-set-field-decoder 'Newsgroups nil nil)
+(mime-set-field-decoder 'Nntp-Posting-Host nil nil)
+(mime-set-field-decoder 'Path nil nil)
+(mime-set-field-decoder 'Posted-And-Mailed nil nil)
+(mime-set-field-decoder 'Received nil nil)
+(mime-set-field-decoder 'Status nil nil)
+(mime-set-field-decoder 'X-Face nil nil)
+(mime-set-field-decoder 'X-Face-Version nil nil)
+(mime-set-field-decoder 'X-Info nil nil)
+(mime-set-field-decoder 'X-Pgp-Key-Info nil nil)
+(mime-set-field-decoder 'X-Pgp-Sig nil nil)
+(mime-set-field-decoder 'X-Pgp-Sig-Version nil nil)
+(mime-set-field-decoder 'Xref nil nil)
+
+;; structured fields
+(let ((fields
+ '(Reply-To Resent-Reply-To From Resent-From Sender Resent-Sender
+ To Resent-To Cc Resent-Cc Bcc Resent-Bcc Dcc
+ Mail-Followup-To
+ Mime-Version Content-Type Content-Transfer-Encoding
+ Content-Disposition User-Agent))
+ field)
+ (while fields
+ (setq field (pop fields))
+ (mime-set-field-decoder
+ field
+ 'plain #'eword-decode-structured-field-body
+ 'wide #'eword-decode-and-fold-structured-field-body
+ 'summary #'eword-decode-and-unfold-structured-field-body
+ 'nov #'eword-decode-and-unfold-structured-field-body)
+ ))
+
+;; unstructured fields (default)
+(mime-set-field-decoder
+ t
+ 'plain #'eword-decode-unstructured-field-body
+ 'wide #'eword-decode-unstructured-field-body
+ 'summary #'eword-decode-and-unfold-unstructured-field-body
+ 'nov #'eword-decode-unfolded-unstructured-field-body)
+
+;;;###autoload
+(defun mime-decode-field-body (field-body field-name
+ &optional mode max-column)
+ "Decode FIELD-BODY as FIELD-NAME in MODE, and return the result.
+Optional argument MODE must be `plain', `wide', `summary' or `nov'.
+Default mode is `summary'.
+
+If MODE is `wide' and MAX-COLUMN is non-nil, the result is folded with
+MAX-COLUMN.
+
+Non MIME encoded-word part in FILED-BODY is decoded with
+`default-mime-charset'."
+ (let (field-name-symbol len decoder)
+ (if (symbolp field-name)
+ (setq field-name-symbol field-name
+ len (1+ (string-width (symbol-name field-name))))
+ (setq field-name-symbol (intern (capitalize field-name))
+ len (1+ (string-width field-name))))
+ (setq decoder (mime-find-field-decoder field-name-symbol mode))
+ (if decoder
+ (funcall decoder field-body len max-column)
+ ;; Don't decode
+ (if (eq mode 'summary)
+ (std11-unfold-string field-body)
+ field-body)
+ )))
+
+;;;###autoload
+(defun mime-decode-header-in-region (start end
+ &optional code-conversion)
+ "Decode MIME encoded-words in region between START and END.