lisp/mh-e/mh-compat.el

   1 ;;; mh-compat.el --- make MH-E compatibile with various versions of Emacs
   2
   3 ;; Copyright (C) 2006 Free Software Foundation, Inc.
   4
   5 ;; Author: Bill Wohler <wohler@newt.com>
   6 ;; Maintainer: Bill Wohler <wohler@newt.com>
   7 ;; Keywords: mail
   8 ;; See: mh-e.el
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software; you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation; either version 2, or (at your option)
  15 ;; any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  25 ;; Boston, MA 02110-1301, USA.
  26
  27 ;;; Commentary:
  28
  29 ;;; Change Log:
  30
  31 ;;; Code:
  32
  33 ;; This is a good place to gather code that is used for compatibility
  34 ;; between different versions of Emacs. Please document which versions
  35 ;; of Emacs that the defsubst, defalias, or defmacro applies. That
  36 ;; way, it's easy to occasionally go through this file and see which
  37 ;; macros we can retire.
  38
  39 ;; Please use mh-gnus.el when providing compatibility with different
  40 ;; versions of Gnus.
  41
  42 ;; Items are listed alphabetically (except for mh-require which is
  43 ;; needed by a lesser character).
  44
  45 (require 'mh-acros)
  46
  47 (mh-do-in-gnu-emacs
  48   (defalias 'mh-require 'require))
  49
  50 (mh-do-in-xemacs
  51   (defun mh-require (feature &optional filename noerror)
  52     "If feature FEATURE is not loaded, load it from FILENAME.
  53 If FEATURE is not a member of the list `features', then the feature
  54 is not loaded; so load the file FILENAME.
  55 If FILENAME is omitted, the printname of FEATURE is used as the file name.
  56 If the optional third argument NOERROR is non-nil,
  57 then return nil if the file is not found instead of signaling an error.
  58
  59 Simulate NOERROR argument in XEmacs which lacks it."
  60     (if (not (featurep feature))
  61         (if filename
  62             (load filename noerror t)
  63           (load (format "%s" feature) noerror t)))))
  64
  65 (mh-defun-compat mh-assoc-string assoc-string (key list case-fold)
  66   "Like `assoc' but specifically for strings.
  67 Case is ignored if CASE-FOLD is non-nil.
  68 This function is used by Emacs versions that lack `assoc-string',
  69 introduced in Emacs 22."
  70   (if case-fold
  71       (assoc-ignore-case key list)
  72     (assoc key list)))
  73
  74 ;; For XEmacs.
  75 (defalias 'mh-cancel-timer
  76   (if (fboundp 'cancel-timer)
  77       'cancel-timer
  78     'delete-itimer))
  79
  80 (mh-defun-compat mh-display-color-cells display-color-cells (&optional display)
  81   "Return the number of color cells supported by DISPLAY.
  82 This function is used by XEmacs to return 2 when
  83 `device-color-cells' returns nil. This happens when compiling or
  84 running on a tty and causes errors since `display-color-cells' is
  85 expected to return an integer."
  86   (or (device-color-cells display) 2))
  87
  88 (defmacro mh-display-completion-list (completions &optional common-substring)
  89   "Display the list of COMPLETIONS.
  90 See documentation for `display-completion-list' for a description of the
  91 arguments COMPLETIONS and perhaps COMMON-SUBSTRING.
  92 This macro is used by Emacs versions that lack a COMMON-SUBSTRING
  93 argument, introduced in Emacs 22."
  94   (if (< emacs-major-version 22)
  95       `(display-completion-list ,completions)
  96     `(display-completion-list ,completions ,common-substring)))
  97
  98 (defmacro mh-face-foreground (face &optional frame inherit)
  99   "Return the foreground color name of FACE, or nil if unspecified.
 100 See documentation for `face-foreground' for a description of the
 101 arguments FACE, FRAME, and perhaps INHERIT.
 102 This macro is used by Emacs versions that lack an INHERIT argument,
 103 introduced in Emacs 22."
 104   (if (< emacs-major-version 22)
 105       `(face-foreground ,face ,frame)
 106     `(face-foreground ,face ,frame ,inherit)))
 107
 108 (defmacro mh-face-background (face &optional frame inherit)
 109   "Return the background color name of face, or nil if unspecified.
 110 See documentation for `back-foreground' for a description of the
 111 arguments FACE, FRAME, and INHERIT.
 112 This macro is used by Emacs versions that lack an INHERIT argument,
 113 introduced in Emacs 22."
 114   (if (< emacs-major-version 22)
 115       `(face-background ,face ,frame)
 116     `(face-background ,face ,frame ,inherit)))
 117
 118 (mh-defun-compat mh-image-load-path-for-library
 119   image-load-path-for-library (library image &optional path no-error)
 120   "Return a suitable search path for images used by LIBRARY.
 121
 122 It searches for IMAGE in `image-load-path' (excluding
 123 \"`data-directory'/images\") and `load-path', followed by a path
 124 suitable for LIBRARY, which includes \"../../etc/images\" and
 125 \"../etc/images\" relative to the library file itself, and then
 126 in \"`data-directory'/images\".
 127
 128 Then this function returns a list of directories which contains
 129 first the directory in which IMAGE was found, followed by the
 130 value of `load-path'. If PATH is given, it is used instead of
 131 `load-path'.
 132
 133 If NO-ERROR is non-nil and a suitable path can't be found, don't
 134 signal an error. Instead, return a list of directories as before,
 135 except that nil appears in place of the image directory.
 136
 137 Here is an example that uses a common idiom to provide
 138 compatibility with versions of Emacs that lack the variable
 139 `image-load-path':
 140
 141     ;; Shush compiler.
 142     (defvar image-load-path)
 143
 144     (let* ((load-path (image-load-path-for-library \"mh-e\" \"mh-logo.xpm\"))
 145            (image-load-path (cons (car load-path)
 146                                   (when (boundp 'image-load-path)
 147                                     image-load-path))))
 148       (mh-tool-bar-folder-buttons-init))"
 149   (unless library (error "No library specified"))
 150   (unless image   (error "No image specified"))
 151   (let (image-directory image-directory-load-path)
 152     ;; Check for images in image-load-path or load-path.
 153     (let ((img image)
 154           (dir (or
 155                 ;; Images in image-load-path.
 156                 (mh-image-search-load-path image)
 157                 ;; Images in load-path.
 158                 (locate-library image)))
 159           parent)
 160       ;; Since the image might be in a nested directory (for
 161       ;; example, mail/attach.pbm), adjust `image-directory'
 162       ;; accordingly.
 163       (when dir
 164         (setq dir (file-name-directory dir))
 165         (while (setq parent (file-name-directory img))
 166           (setq img (directory-file-name parent)
 167                 dir (expand-file-name "../" dir))))
 168       (setq image-directory-load-path dir))
 169
 170     ;; If `image-directory-load-path' isn't Emacs' image directory,
 171     ;; it's probably a user preference, so use it. Then use a
 172     ;; relative setting if possible; otherwise, use
 173     ;; `image-directory-load-path'.
 174     (cond
 175      ;; User-modified image-load-path?
 176      ((and image-directory-load-path
 177            (not (equal image-directory-load-path
 178                        (file-name-as-directory
 179                         (expand-file-name "images" data-directory)))))
 180       (setq image-directory image-directory-load-path))
 181      ;; Try relative setting.
 182      ((let (library-name d1ei d2ei)
 183         ;; First, find library in the load-path.
 184         (setq library-name (locate-library library))
 185         (if (not library-name)
 186             (error "Cannot find library %s in load-path" library))
 187         ;; And then set image-directory relative to that.
 188         (setq
 189          ;; Go down 2 levels.
 190          d2ei (file-name-as-directory
 191                (expand-file-name
 192                 (concat (file-name-directory library-name) "../../etc/images")))
 193          ;; Go down 1 level.
 194          d1ei (file-name-as-directory
 195                (expand-file-name
 196                 (concat (file-name-directory library-name) "../etc/images"))))
 197         (setq image-directory
 198               ;; Set it to nil if image is not found.
 199               (cond ((file-exists-p (expand-file-name image d2ei)) d2ei)
 200                     ((file-exists-p (expand-file-name image d1ei)) d1ei)))))
 201      ;; Use Emacs' image directory.
 202      (image-directory-load-path
 203       (setq image-directory image-directory-load-path))
 204      (no-error
 205       (message "Could not find image %s for library %s" image library))
 206      (t
 207       (error "Could not find image %s for library %s" image library)))
 208
 209     ;; Return an augmented `path' or `load-path'.
 210     (nconc (list image-directory)
 211            (delete image-directory (copy-sequence (or path load-path))))))
 212
 213 (mh-defun-compat mh-image-search-load-path
 214   image-search-load-path (file &optional path)
 215   "Emacs 21 and XEmacs don't have `image-search-load-path'.
 216 This function returns nil on those systems."
 217   nil)
 218
 219 ;; For XEmacs.
 220 (defalias 'mh-line-beginning-position
 221   (if (fboundp 'line-beginning-position)
 222       'line-beginning-position
 223     'point-at-bol))
 224
 225 ;; For XEmacs.
 226 (defalias 'mh-line-end-position
 227   (if (fboundp 'line-end-position)
 228       'line-end-position
 229     'point-at-eol))
 230
 231 (mh-require 'mailabbrev nil t)
 232 (mh-defun-compat mh-mail-abbrev-make-syntax-table
 233   mail-abbrev-make-syntax-table ()
 234   "Emacs 21 and XEmacs don't have `mail-abbrev-make-syntax-table'.
 235 This function returns nil on those systems."
 236   nil)
 237
 238 (mh-defun-compat mh-match-string-no-properties
 239   match-string-no-properties (num &optional string)
 240   "Return string of text matched by last search, without text properties.
 241 This function is used by XEmacs that lacks `match-string-no-properties'.
 242 The function `buffer-substring-no-properties' is used instead.
 243 The argument STRING is ignored."
 244   (buffer-substring-no-properties
 245    (match-beginning num) (match-end num)))
 246
 247 (mh-defun-compat mh-replace-regexp-in-string replace-regexp-in-string
 248   (regexp rep string &optional fixedcase literal subexp start)
 249   "Replace REGEXP with REP everywhere in STRING and return result.
 250 This function is used by XEmacs that lacks `replace-regexp-in-string'.
 251 The function `replace-in-string' is used instead.
 252 The arguments FIXEDCASE, SUBEXP, and START, used by
 253 `replace-in-string' are ignored."
 254   (replace-in-string string regexp rep literal))
 255
 256 ;; Copy of constant from url-util.el in Emacs 22; needed by Emacs 21.
 257 (if (not (boundp 'url-unreserved-chars))
 258     (defconst mh-url-unreserved-chars
 259       '(
 260         ?a ?b ?c ?d ?e ?f ?g ?h ?i ?j ?k ?l ?m ?n ?o ?p ?q ?r ?s ?t ?u ?v ?w ?x ?y ?z
 261         ?A ?B ?C ?D ?E ?F ?G ?H ?I ?J ?K ?L ?M ?N ?O ?P ?Q ?R ?S ?T ?U ?V ?W ?X ?Y ?Z
 262         ?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9
 263         ?- ?_ ?. ?! ?~ ?* ?' ?\( ?\))
 264       "A list of characters that are _NOT_ reserved in the URL spec.
 265 This is taken from RFC 2396."))
 266
 267 (mh-defun-compat mh-url-hexify-string url-hexify-string (str)
 268   "Escape characters in a string.
 269 This is a copy of `url-hexify-string' from url-util.el in Emacs
 270 22; needed by Emacs 21."
 271   (mapconcat
 272    (lambda (char)
 273      ;; Fixme: use a char table instead.
 274      (if (not (memq char mh-url-unreserved-chars))
 275          (if (> char 255)
 276                (error "Hexifying multibyte character %s" str)
 277            (format "%%%02X" char))
 278        (char-to-string char)))
 279    str ""))
 280
 281 (mh-defun-compat mh-view-mode-enter
 282   view-mode-enter (&optional return-to exit-action)
 283   "Enter View mode.
 284 This function is used by XEmacs that lacks `view-mode-enter'.
 285 The function `view-mode' is used instead.
 286 The arguments RETURN-TO and EXIT-ACTION are ignored."
 287   ;; Shush compiler.
 288   (if return-to nil)
 289   (if exit-action nil)
 290   (view-mode 1))
 291
 292 (defmacro mh-write-file-functions ()
 293   "Return `write-file-functions' if it exists.
 294 Otherwise return `local-write-file-hooks'.
 295 This macro exists purely for compatibility. The former symbol is used
 296 in Emacs 22 onward while the latter is used in previous versions and
 297 XEmacs."
 298   (if (boundp 'write-file-functions)
 299       ''write-file-functions            ;Emacs 22 on
 300     ''local-write-file-hooks))          ;XEmacs
 301
 302 (provide 'mh-compat)
 303
 304 ;; Local Variables:
 305 ;; no-byte-compile: t
 306 ;; indent-tabs-mode: nil
 307 ;; sentence-end-double-space: nil
 308 ;; End:
 309
 310 ;; arch-tag: 577b0eab-a5cd-45e1-8d9f-c1a426f4d73c
 311 ;;; mh-compat.el ends here