Function: mail-header-extract

mail-header-extract is an autoloaded and byte-compiled function defined in mailheader.el.gz.

Signature

(mail-header-extract)

Documentation

Extract headers from current buffer after point.

Returns a header alist, where each element is a cons cell (name . value), where NAME is a symbol, and VALUE is the string value of the header having that name.

Source Code

;; Defined in /usr/src/emacs/lisp/mail/mailheader.el.gz
;;; mailheader.el --- mail header parsing, merging, formatting  -*- lexical-binding: t; -*-

;; Copyright (C) 1996, 2001-2025 Free Software Foundation, Inc.

;; Author: Erik Naggum <erik@naggum.no>
;; Keywords: tools, mail, news
;; Package: mail-utils

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; This package provides an abstraction of RFC 822 (or later) format, used in
;; mail, news, and some other systems.  The simple syntactic rules for such
;; headers, such as quoting and line folding, are routinely reimplemented
;; in many individual packages.  This package removes the need for this
;; redundancy by representing message headers as association lists,
;; offering functions to extract the set of headers from a message, to
;; parse individual headers, to merge sets of headers, and to format a set
;; of headers.

;; The car of each element in the message-header alist is a symbol whose
;; print name is the name of the header, in all lower-case.  The cdr of an
;; element depends on the operation.  After extracting headers from a
;; message, it is a string, the value of the header.  An extracted set of
;; headers may be parsed further, which may turn it into a list, whose car
;; is the original value and whose subsequent elements depend on the
;; header.  For formatting, it is evaluated to obtain the strings to be
;; inserted.  For merging, one set of headers consists of strings, while
;; the other set will be evaluated with the symbols in the first set of
;; headers bound to their respective values.

;;; Code:

(defun mail-header-extract ()
  "Extract headers from current buffer after point.
Returns a header alist, where each element is a cons cell (name . value),
where NAME is a symbol, and VALUE is the string value of the header having
that name."
  (let ((message-headers ()) (top (point))
	start end)
    (while (and (setq start (point))
		(> (skip-chars-forward "^\0- :") 0)
		(= (following-char) ?:)
		(setq end (point))
		(progn (forward-char)
		       (> (skip-chars-forward " \t") 0)))
      (let ((header (intern (downcase (buffer-substring start end))))
	    (value (list (buffer-substring
			  (point) (progn (end-of-line) (point))))))
	(while (progn (forward-char) (> (skip-chars-forward " \t") 0))
	  (push (buffer-substring (point) (progn (end-of-line) (point)))
		value))
	(push (if (cdr value)
		  (cons header (mapconcat #'identity (nreverse value) " "))
		  (cons header (car value)))
	      message-headers)))
    (goto-char top)
    (nreverse message-headers)))