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cc8d8b6f | 1 | ;;; mailheader.el --- Mail header parsing, merging, formatting |
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2 | |
3 | ;; Copyright (C) 1996 by Free Software Foundation, Inc. | |
4 | ||
5 | ;; Author: Erik Naggum <erik@arcana.naggum.no> | |
6 | ;; Keywords: tools, mail, news | |
7 | ||
8 | ;; This file is part of GNU Emacs. | |
9 | ||
10 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
11 | ;; it under the terms of the GNU General Public License as published by | |
12 | ;; the Free Software Foundation; either version 2, or (at your option) | |
13 | ;; any later version. | |
14 | ||
15 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;; GNU General Public License for more details. | |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
21 | ;; along with GNU Emacs; see the file COPYING. If not, write to | |
22 | ;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | ;; Boston, MA 02111-1307, USA. | |
24 | ||
25 | ;;; Commentary: | |
26 | ||
27 | ;; This package provides an abstraction to RFC822-style messages, used in | |
cc8d8b6f | 28 | ;; mail, news, and some other systems. The simple syntactic rules for such |
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29 | ;; headers, such as quoting and line folding, are routinely reimplemented |
30 | ;; in many individual packages. This package removes the need for this | |
31 | ;; redundancy by representing message headers as association lists, | |
32 | ;; offering functions to extract the set of headers from a message, to | |
33 | ;; parse individual headers, to merge sets of headers, and to format a set | |
34 | ;; of headers. | |
35 | ||
36 | ;; The car of each element in the message-header alist is a symbol whose | |
37 | ;; print name is the name of the header, in all lower-case. The cdr of an | |
38 | ;; element depends on the operation. After extracting headers from a | |
39 | ;; messge, it is a string, the value of the header. An extracted set of | |
40 | ;; headers may be parsed further, which may turn it into a list, whose car | |
41 | ;; is the original value and whose subsequent elements depend on the | |
42 | ;; header. For formatting, it is evaluated to obtain the strings to be | |
43 | ;; inserted. For merging, one set of headers consists of strings, while | |
44 | ;; the other set will be evaluated with the symbols in the first set of | |
45 | ;; headers bound to their respective values. | |
46 | ||
47 | ;;; Code: | |
48 | ||
cc8d8b6f EN |
49 | (eval-when-compile |
50 | (require 'cl)) | |
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51 | |
52 | ;; Make the byte-compiler shut up. | |
53 | (defvar headers) | |
54 | ||
55 | (defun mail-header-extract () | |
56 | "Extract headers from current buffer after point. | |
57 | Returns a header alist, where each element is a cons cell (name . value), | |
58 | where NAME is a symbol, and VALUE is the string value of the header having | |
59 | that name." | |
60 | (let ((message-headers ()) (top (point)) | |
61 | start end) | |
62 | (while (and (setq start (point)) | |
63 | (> (skip-chars-forward "^\0- :") 0) | |
64 | (= (following-char) ?:) | |
65 | (setq end (point)) | |
66 | (progn (forward-char) | |
67 | (> (skip-chars-forward " \t") 0))) | |
68 | (let ((header (intern (downcase (buffer-substring start end)))) | |
69 | (value (list (buffer-substring | |
70 | (point) (progn (end-of-line) (point)))))) | |
71 | (while (progn (forward-char) (> (skip-chars-forward " \t") 0)) | |
72 | (push (buffer-substring (point) (progn (end-of-line) (point))) | |
73 | value)) | |
74 | (push (if (cdr value) | |
75 | (cons header (mapconcat #'identity (nreverse value) " ")) | |
76 | (cons header (car value))) | |
77 | message-headers))) | |
78 | (goto-char top) | |
79 | (nreverse message-headers))) | |
80 | ||
81 | (defun mail-header-extract-no-properties () | |
82 | "Extract headers from current buffer after point, without properties. | |
83 | Returns a header alist, where each element is a cons cell (name . value), | |
84 | where NAME is a symbol, and VALUE is the string value of the header having | |
85 | that name." | |
86 | (mapcar | |
87 | (lambda (elt) | |
88 | (set-text-properties 0 (length (cdr elt)) nil (cdr elt)) | |
89 | elt) | |
90 | (mail-header-extract))) | |
91 | ||
92 | (defun mail-header-parse (parsing-rules headers) | |
93 | "Apply PARSING-RULES to HEADERS. | |
94 | PARSING-RULES is an alist whose keys are header names (symbols) and whose | |
95 | value is a parsing function. The function takes one argument, a string, | |
96 | and return a list of values, which will destructively replace the value | |
97 | associated with the key in HEADERS, after being prepended with the original | |
98 | value." | |
99 | (dolist (rule parsing-rules) | |
100 | (let ((header (assq (car rule) headers))) | |
101 | (when header | |
102 | (if (consp (cdr header)) | |
103 | (setf (cddr header) (funcall (cdr rule) (cadr header))) | |
104 | (setf (cdr header) | |
105 | (cons (cdr header) (funcall (cdr rule) (cdr header)))))))) | |
106 | headers) | |
107 | ||
108 | (defsubst mail-header (header &optional header-alist) | |
109 | "Return the value associated with header HEADER in HEADER-ALIST. | |
110 | If the value is a string, it is the original value of the header. If the | |
111 | value is a list, its first element is the original value of the header, | |
112 | with any subsequent elements bing the result of parsing the value. | |
113 | If HEADER-ALIST is nil, the dynamically bound variable `headers' is used." | |
114 | (cdr (assq header (or header-alist headers)))) | |
115 | ||
116 | (defun mail-header-set (header value &optional header-alist) | |
117 | "Set the value associated with header HEADER to VALUE in HEADER-ALIST. | |
118 | HEADER-ALIST defaults to the dynamically bound variable `headers' if nil. | |
119 | See `mail-header' for the semantics of VALUE." | |
120 | (let* ((alist (or header-alist headers)) | |
121 | (entry (assq header alist))) | |
122 | (if entry | |
123 | (setf (cdr entry) value) | |
124 | (nconc alist (list (cons header value))))) | |
125 | value) | |
126 | ||
127 | (defsetf mail-header (header &optional header-alist) (value) | |
128 | `(mail-header-set ,header ,value ,header-alist)) | |
129 | ||
130 | (defun mail-header-merge (merge-rules headers) | |
131 | "Return a new header alist with MERGE-RULES applied to HEADERS. | |
132 | MERGE-RULES is an alist whose keys are header names (symbols) and whose | |
133 | values are forms to evaluate, the results of which are the new headers. It | |
134 | should be a string or a list of string. The first element may be nil to | |
135 | denote that the formatting functions must use the remaining elements, or | |
136 | skip the header altogether if there are no other elements. | |
137 | The macro `mail-header' can be used to access headers in HEADERS." | |
138 | (mapcar | |
139 | (lambda (rule) | |
140 | (cons (car rule) (eval (cdr rule)))) | |
141 | merge-rules)) | |
142 | ||
143 | (defvar mail-header-format-function | |
144 | (lambda (header value) | |
145 | "Function to format headers without a specified formatting function." | |
146 | (insert (capitalize (symbol-name header)) | |
147 | ": " | |
148 | (if (consp value) (car value) value) | |
149 | "\n"))) | |
150 | ||
151 | (defun mail-header-format (format-rules headers) | |
152 | "Use FORMAT-RULES to format HEADERS and insert into current buffer. | |
68cf9ca1 RS |
153 | HEADERS should be an alist of the form (HEADER . VALUE), |
154 | where HEADER is a header field name (a symbol or a string), | |
155 | and VALUE is the contents for that header field. | |
156 | ||
157 | FORMAT-RULES is an alist of elements (HEADER . FUNCTION) Here HEADER | |
158 | is a header field name (a symbol), and FUNCTION is how to format that | |
159 | header field, if it appears in HEADERS. Each FUNCTION should take two | |
160 | arguments: the header symbol, and the value of that header. The value | |
161 | returned by FUNCTION is inserted in the buffer unless it is nil. | |
162 | ||
163 | If the function for a header field is nil, or if no function is | |
164 | specified for a particular header field, the default action is to | |
165 | insert the value of the header, unless it is nil. | |
166 | ||
526baa41 | 167 | The headers are inserted in the order of the FORMAT-RULES. |
68cf9ca1 | 168 | A key of t in FORMAT-RULES. represents any otherwise unmentioned headers. |
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169 | A key of nil has as its value a list of defaulted headers to ignore." |
170 | (let ((ignore (append (cdr (assq nil format-rules)) | |
171 | (mapcar #'car format-rules)))) | |
172 | (dolist (rule format-rules) | |
173 | (let* ((header (car rule)) | |
174 | (value (mail-header header))) | |
68cf9ca1 RS |
175 | (if (stringp header) |
176 | (setq header (intern header))) | |
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177 | (cond ((null header) 'ignore) |
178 | ((eq header t) | |
179 | (dolist (defaulted headers) | |
180 | (unless (memq (car defaulted) ignore) | |
181 | (let* ((header (car defaulted)) | |
182 | (value (cdr defaulted))) | |
183 | (if (cdr rule) | |
184 | (funcall (cdr rule) header value) | |
68cf9ca1 | 185 | (funcall mail-header-format-function header value)))))) |
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186 | (value |
187 | (if (cdr rule) | |
188 | (funcall (cdr rule) header value) | |
68cf9ca1 | 189 | (funcall mail-header-format-function header value)))))) |
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190 | (insert "\n"))) |
191 | ||
192 | (provide 'mailheader) | |
193 | ||
cc8d8b6f | 194 | ;;; mailheader.el ends here |