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e8af40ee | 1 | ;;; mailheader.el --- mail header parsing, merging, formatting |
526baa41 | 2 | |
f2e3589a | 3 | ;; Copyright (C) 1996, 2001, 2002, 2003, 2004, 2005, |
2f043267 | 4 | ;; 2006, 2007, 2008 Free Software Foundation, Inc. |
526baa41 | 5 | |
a893064d | 6 | ;; Author: Erik Naggum <erik@naggum.no> |
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7 | ;; Keywords: tools, mail, news |
8 | ||
9 | ;; This file is part of GNU Emacs. | |
10 | ||
11 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
12 | ;; it under the terms of the GNU General Public License as published by | |
ceaeecb0 | 13 | ;; the Free Software Foundation; either version 3, or (at your option) |
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14 | ;; any later version. |
15 | ||
16 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
17 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
19 | ;; GNU General Public License for more details. | |
20 | ||
21 | ;; You should have received a copy of the GNU General Public License | |
22 | ;; along with GNU Emacs; see the file COPYING. If not, write to | |
3a35cf56 LK |
23 | ;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
24 | ;; Boston, MA 02110-1301, USA. | |
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25 | |
26 | ;;; Commentary: | |
27 | ||
28 | ;; This package provides an abstraction to RFC822-style messages, used in | |
cc8d8b6f | 29 | ;; mail, news, and some other systems. The simple syntactic rules for such |
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30 | ;; headers, such as quoting and line folding, are routinely reimplemented |
31 | ;; in many individual packages. This package removes the need for this | |
32 | ;; redundancy by representing message headers as association lists, | |
33 | ;; offering functions to extract the set of headers from a message, to | |
34 | ;; parse individual headers, to merge sets of headers, and to format a set | |
35 | ;; of headers. | |
36 | ||
37 | ;; The car of each element in the message-header alist is a symbol whose | |
38 | ;; print name is the name of the header, in all lower-case. The cdr of an | |
39 | ;; element depends on the operation. After extracting headers from a | |
51c39cdb | 40 | ;; message, it is a string, the value of the header. An extracted set of |
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41 | ;; headers may be parsed further, which may turn it into a list, whose car |
42 | ;; is the original value and whose subsequent elements depend on the | |
43 | ;; header. For formatting, it is evaluated to obtain the strings to be | |
44 | ;; inserted. For merging, one set of headers consists of strings, while | |
45 | ;; the other set will be evaluated with the symbols in the first set of | |
46 | ;; headers bound to their respective values. | |
47 | ||
48 | ;;; Code: | |
49 | ||
cc8d8b6f EN |
50 | (eval-when-compile |
51 | (require 'cl)) | |
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52 | |
53 | ;; Make the byte-compiler shut up. | |
54 | (defvar headers) | |
55 | ||
56 | (defun mail-header-extract () | |
57 | "Extract headers from current buffer after point. | |
58 | Returns a header alist, where each element is a cons cell (name . value), | |
59 | where NAME is a symbol, and VALUE is the string value of the header having | |
60 | that name." | |
61 | (let ((message-headers ()) (top (point)) | |
62 | start end) | |
63 | (while (and (setq start (point)) | |
64 | (> (skip-chars-forward "^\0- :") 0) | |
65 | (= (following-char) ?:) | |
66 | (setq end (point)) | |
8f09e440 | 67 | (progn (forward-char) |
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68 | (> (skip-chars-forward " \t") 0))) |
69 | (let ((header (intern (downcase (buffer-substring start end)))) | |
70 | (value (list (buffer-substring | |
71 | (point) (progn (end-of-line) (point)))))) | |
72 | (while (progn (forward-char) (> (skip-chars-forward " \t") 0)) | |
73 | (push (buffer-substring (point) (progn (end-of-line) (point))) | |
74 | value)) | |
75 | (push (if (cdr value) | |
76 | (cons header (mapconcat #'identity (nreverse value) " ")) | |
77 | (cons header (car value))) | |
78 | message-headers))) | |
79 | (goto-char top) | |
80 | (nreverse message-headers))) | |
81 | ||
82 | (defun mail-header-extract-no-properties () | |
83 | "Extract headers from current buffer after point, without properties. | |
84 | Returns a header alist, where each element is a cons cell (name . value), | |
85 | where NAME is a symbol, and VALUE is the string value of the header having | |
86 | that name." | |
87 | (mapcar | |
88 | (lambda (elt) | |
89 | (set-text-properties 0 (length (cdr elt)) nil (cdr elt)) | |
90 | elt) | |
91 | (mail-header-extract))) | |
92 | ||
93 | (defun mail-header-parse (parsing-rules headers) | |
94 | "Apply PARSING-RULES to HEADERS. | |
95 | PARSING-RULES is an alist whose keys are header names (symbols) and whose | |
96 | value is a parsing function. The function takes one argument, a string, | |
97 | and return a list of values, which will destructively replace the value | |
98 | associated with the key in HEADERS, after being prepended with the original | |
99 | value." | |
100 | (dolist (rule parsing-rules) | |
101 | (let ((header (assq (car rule) headers))) | |
102 | (when header | |
103 | (if (consp (cdr header)) | |
104 | (setf (cddr header) (funcall (cdr rule) (cadr header))) | |
105 | (setf (cdr header) | |
106 | (cons (cdr header) (funcall (cdr rule) (cdr header)))))))) | |
107 | headers) | |
108 | ||
109 | (defsubst mail-header (header &optional header-alist) | |
110 | "Return the value associated with header HEADER in HEADER-ALIST. | |
111 | If the value is a string, it is the original value of the header. If the | |
112 | value is a list, its first element is the original value of the header, | |
8f09e440 | 113 | with any subsequent elements being the result of parsing the value. |
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114 | If HEADER-ALIST is nil, the dynamically bound variable `headers' is used." |
115 | (cdr (assq header (or header-alist headers)))) | |
116 | ||
117 | (defun mail-header-set (header value &optional header-alist) | |
118 | "Set the value associated with header HEADER to VALUE in HEADER-ALIST. | |
119 | HEADER-ALIST defaults to the dynamically bound variable `headers' if nil. | |
120 | See `mail-header' for the semantics of VALUE." | |
121 | (let* ((alist (or header-alist headers)) | |
122 | (entry (assq header alist))) | |
123 | (if entry | |
124 | (setf (cdr entry) value) | |
125 | (nconc alist (list (cons header value))))) | |
126 | value) | |
127 | ||
128 | (defsetf mail-header (header &optional header-alist) (value) | |
129 | `(mail-header-set ,header ,value ,header-alist)) | |
130 | ||
131 | (defun mail-header-merge (merge-rules headers) | |
132 | "Return a new header alist with MERGE-RULES applied to HEADERS. | |
133 | MERGE-RULES is an alist whose keys are header names (symbols) and whose | |
134 | values are forms to evaluate, the results of which are the new headers. It | |
135 | should be a string or a list of string. The first element may be nil to | |
136 | denote that the formatting functions must use the remaining elements, or | |
137 | skip the header altogether if there are no other elements. | |
138 | The macro `mail-header' can be used to access headers in HEADERS." | |
139 | (mapcar | |
140 | (lambda (rule) | |
141 | (cons (car rule) (eval (cdr rule)))) | |
142 | merge-rules)) | |
143 | ||
144 | (defvar mail-header-format-function | |
145 | (lambda (header value) | |
146 | "Function to format headers without a specified formatting function." | |
147 | (insert (capitalize (symbol-name header)) | |
148 | ": " | |
149 | (if (consp value) (car value) value) | |
15575807 | 150 | "\n"))) |
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151 | |
152 | (defun mail-header-format (format-rules headers) | |
153 | "Use FORMAT-RULES to format HEADERS and insert into current buffer. | |
68cf9ca1 RS |
154 | HEADERS should be an alist of the form (HEADER . VALUE), |
155 | where HEADER is a header field name (a symbol or a string), | |
156 | and VALUE is the contents for that header field. | |
157 | ||
158 | FORMAT-RULES is an alist of elements (HEADER . FUNCTION) Here HEADER | |
159 | is a header field name (a symbol), and FUNCTION is how to format that | |
160 | header field, if it appears in HEADERS. Each FUNCTION should take two | |
161 | arguments: the header symbol, and the value of that header. The value | |
162 | returned by FUNCTION is inserted in the buffer unless it is nil. | |
163 | ||
164 | If the function for a header field is nil, or if no function is | |
165 | specified for a particular header field, the default action is to | |
166 | insert the value of the header, unless it is nil. | |
167 | ||
526baa41 | 168 | The headers are inserted in the order of the FORMAT-RULES. |
8f09e440 | 169 | A key of t in FORMAT-RULES represents any otherwise unmentioned headers. |
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170 | A key of nil has as its value a list of defaulted headers to ignore." |
171 | (let ((ignore (append (cdr (assq nil format-rules)) | |
172 | (mapcar #'car format-rules)))) | |
173 | (dolist (rule format-rules) | |
174 | (let* ((header (car rule)) | |
175 | (value (mail-header header))) | |
68cf9ca1 RS |
176 | (if (stringp header) |
177 | (setq header (intern header))) | |
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178 | (cond ((null header) 'ignore) |
179 | ((eq header t) | |
180 | (dolist (defaulted headers) | |
181 | (unless (memq (car defaulted) ignore) | |
182 | (let* ((header (car defaulted)) | |
183 | (value (cdr defaulted))) | |
184 | (if (cdr rule) | |
185 | (funcall (cdr rule) header value) | |
68cf9ca1 | 186 | (funcall mail-header-format-function header value)))))) |
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187 | (value |
188 | (if (cdr rule) | |
189 | (funcall (cdr rule) header value) | |
68cf9ca1 | 190 | (funcall mail-header-format-function header value)))))) |
15575807 | 191 | (insert "\n"))) |
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192 | |
193 | (provide 'mailheader) | |
194 | ||
cbee283d | 195 | ;; arch-tag: 6e7aa221-80b5-4b3d-b46f-fd66ab567be0 |
cc8d8b6f | 196 | ;;; mailheader.el ends here |