lisp/mh-e/mh-compat.el

   1 ;;; mh-compat.el --- make MH-E compatibile with various versions of Emacs
   2
   3 ;; Copyright (C) 2006, 2007, 2008 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 3 of the License, or
  15 ;; (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;;; Change Log:
  28
  29 ;;; Code:
  30
  31 ;; This is a good place to gather code that is used for compatibility
  32 ;; between different versions of Emacs. Please document which versions
  33 ;; of Emacs that the defsubst, defalias, or defmacro applies. That
  34 ;; way, it's easy to occasionally go through this file and see which
  35 ;; macros we can retire.
  36
  37 ;; Please use mh-gnus.el when providing compatibility with different
  38 ;; versions of Gnus.
  39
  40 ;; Items are listed alphabetically (except for mh-require which is
  41 ;; needed sooner it would normally appear).
  42
  43 (require 'mh-acros)
  44
  45 (mh-do-in-gnu-emacs
  46   (defalias 'mh-require 'require))
  47
  48 (mh-do-in-xemacs
  49   (defun mh-require (feature &optional filename noerror)
  50     "If feature FEATURE is not loaded, load it from FILENAME.
  51 If FEATURE is not a member of the list `features', then the feature
  52 is not loaded; so load the file FILENAME.
  53 If FILENAME is omitted, the printname of FEATURE is used as the file name.
  54 If the optional third argument NOERROR is non-nil,
  55 then return nil if the file is not found instead of signaling an error.
  56
  57 Simulate NOERROR argument in XEmacs which lacks it."
  58     (if (not (featurep feature))
  59         (if filename
  60             (load filename noerror t)
  61           (load (format "%s" feature) noerror t)))))
  62
  63 (defun-mh mh-assoc-string assoc-string (key list case-fold)
  64   "Like `assoc' but specifically for strings.
  65 Case is ignored if CASE-FOLD is non-nil.
  66 This function is used by Emacs versions that lack `assoc-string',
  67 introduced in Emacs 22."
  68   (if case-fold
  69       (assoc-ignore-case key list)
  70     (assoc key list)))
  71
  72 ;; For XEmacs.
  73 (defalias 'mh-cancel-timer
  74   (if (fboundp 'cancel-timer)
  75       'cancel-timer
  76     'delete-itimer))
  77
  78 (defun mh-display-color-cells (&optional display)
  79   "Return the number of color cells supported by DISPLAY.
  80 This function is used by XEmacs to return 2 when `device-color-cells'
  81 or `display-color-cells' returns nil. This happens when compiling or
  82 running on a tty and causes errors since `display-color-cells' is
  83 expected to return an integer."
  84   (cond ((fboundp 'display-color-cells) ; GNU Emacs, XEmacs 21.5b28
  85          (or (display-color-cells display) 2))
  86         ((fboundp 'device-color-cells)  ; XEmacs 21.4
  87          (or (device-color-cells display) 2))
  88         (t 2)))
  89
  90 (defmacro mh-display-completion-list (completions &optional common-substring)
  91   "Display the list of COMPLETIONS.
  92 See documentation for `display-completion-list' for a description of the
  93 arguments COMPLETIONS and perhaps COMMON-SUBSTRING.
  94 This macro is used by Emacs versions that lack a COMMON-SUBSTRING
  95 argument, introduced in Emacs 22."
  96   (if (< emacs-major-version 22)
  97       `(display-completion-list ,completions)
  98     `(display-completion-list ,completions ,common-substring)))
  99
 100 (defmacro mh-face-foreground (face &optional frame inherit)
 101   "Return the foreground color name of FACE, or nil if unspecified.
 102 See documentation for `face-foreground' for a description of the
 103 arguments FACE, FRAME, and perhaps INHERIT.
 104 This macro is used by Emacs versions that lack an INHERIT argument,
 105 introduced in Emacs 22."
 106   (if (< emacs-major-version 22)
 107       `(face-foreground ,face ,frame)
 108     `(face-foreground ,face ,frame ,inherit)))
 109
 110 (defmacro mh-face-background (face &optional frame inherit)
 111   "Return the background color name of face, or nil if unspecified.
 112 See documentation for `back-foreground' for a description of the
 113 arguments FACE, FRAME, and INHERIT.
 114 This macro is used by Emacs versions that lack an INHERIT argument,
 115 introduced in Emacs 22."
 116   (if (< emacs-major-version 22)
 117       `(face-background ,face ,frame)
 118     `(face-background ,face ,frame ,inherit)))
 119
 120 (defun-mh mh-font-lock-add-keywords font-lock-add-keywords
 121   (mode keywords &optional how)
 122   "XEmacs does not have `font-lock-add-keywords'.
 123 This function returns nil on that system.")
 124
 125 (defun-mh mh-image-load-path-for-library
 126   image-load-path-for-library (library image &optional path no-error)
 127   "Return a suitable search path for images used by LIBRARY.
 128
 129 It searches for IMAGE in `image-load-path' (excluding
 130 \"`data-directory'/images\") and `load-path', followed by a path
 131 suitable for LIBRARY, which includes \"../../etc/images\" and
 132 \"../etc/images\" relative to the library file itself, and then
 133 in \"`data-directory'/images\".
 134
 135 Then this function returns a list of directories which contains
 136 first the directory in which IMAGE was found, followed by the
 137 value of `load-path'. If PATH is given, it is used instead of
 138 `load-path'.
 139
 140 If NO-ERROR is non-nil and a suitable path can't be found, don't
 141 signal an error. Instead, return a list of directories as before,
 142 except that nil appears in place of the image directory.
 143
 144 Here is an example that uses a common idiom to provide
 145 compatibility with versions of Emacs that lack the variable
 146 `image-load-path':
 147
 148     ;; Shush compiler.
 149     (defvar image-load-path)
 150
 151     (let* ((load-path (image-load-path-for-library \"mh-e\" \"mh-logo.xpm\"))
 152            (image-load-path (cons (car load-path)
 153                                   (when (boundp 'image-load-path)
 154                                     image-load-path))))
 155       (mh-tool-bar-folder-buttons-init))"
 156   (unless library (error "No library specified"))
 157   (unless image   (error "No image specified"))
 158   (let (image-directory image-directory-load-path)
 159     ;; Check for images in image-load-path or load-path.
 160     (let ((img image)
 161           (dir (or
 162                 ;; Images in image-load-path.
 163                 (mh-image-search-load-path image)
 164                 ;; Images in load-path.
 165                 (locate-library image)))
 166           parent)
 167       ;; Since the image might be in a nested directory (for
 168       ;; example, mail/attach.pbm), adjust `image-directory'
 169       ;; accordingly.
 170       (when dir
 171         (setq dir (file-name-directory dir))
 172         (while (setq parent (file-name-directory img))
 173           (setq img (directory-file-name parent)
 174                 dir (expand-file-name "../" dir))))
 175       (setq image-directory-load-path dir))
 176
 177     ;; If `image-directory-load-path' isn't Emacs' image directory,
 178     ;; it's probably a user preference, so use it. Then use a
 179     ;; relative setting if possible; otherwise, use
 180     ;; `image-directory-load-path'.
 181     (cond
 182      ;; User-modified image-load-path?
 183      ((and image-directory-load-path
 184            (not (equal image-directory-load-path
 185                        (file-name-as-directory
 186                         (expand-file-name "images" data-directory)))))
 187       (setq image-directory image-directory-load-path))
 188      ;; Try relative setting.
 189      ((let (library-name d1ei d2ei)
 190         ;; First, find library in the load-path.
 191         (setq library-name (locate-library library))
 192         (if (not library-name)
 193             (error "Cannot find library %s in load-path" library))
 194         ;; And then set image-directory relative to that.
 195         (setq
 196          ;; Go down 2 levels.
 197          d2ei (file-name-as-directory
 198                (expand-file-name
 199                 (concat (file-name-directory library-name) "../../etc/images")))
 200          ;; Go down 1 level.
 201          d1ei (file-name-as-directory
 202                (expand-file-name
 203                 (concat (file-name-directory library-name) "../etc/images"))))
 204         (setq image-directory
 205               ;; Set it to nil if image is not found.
 206               (cond ((file-exists-p (expand-file-name image d2ei)) d2ei)
 207                     ((file-exists-p (expand-file-name image d1ei)) d1ei)))))
 208      ;; Use Emacs' image directory.
 209      (image-directory-load-path
 210       (setq image-directory image-directory-load-path))
 211      (no-error
 212       (message "Could not find image %s for library %s" image library))
 213      (t
 214       (error "Could not find image %s for library %s" image library)))
 215
 216     ;; Return an augmented `path' or `load-path'.
 217     (nconc (list image-directory)
 218            (delete image-directory (copy-sequence (or path load-path))))))
 219
 220 (defun-mh mh-image-search-load-path
 221   image-search-load-path (file &optional path)
 222   "Emacs 21 and XEmacs don't have `image-search-load-path'.
 223 This function returns nil on those systems."
 224   nil)
 225
 226 ;; For XEmacs.
 227 (defalias 'mh-line-beginning-position
 228   (if (fboundp 'line-beginning-position)
 229       'line-beginning-position
 230     'point-at-bol))
 231
 232 ;; For XEmacs.
 233 (defalias 'mh-line-end-position
 234   (if (fboundp 'line-end-position)
 235       'line-end-position
 236     'point-at-eol))
 237
 238 (mh-require 'mailabbrev nil t)
 239 (defun-mh mh-mail-abbrev-make-syntax-table
 240   mail-abbrev-make-syntax-table ()
 241   "Emacs 21 and XEmacs don't have `mail-abbrev-make-syntax-table'.
 242 This function returns nil on those systems."
 243   nil)
 244
 245 (defun-mh mh-match-string-no-properties
 246   match-string-no-properties (num &optional string)
 247   "Return string of text matched by last search, without text properties.
 248 This function is used by XEmacs that lacks `match-string-no-properties'.
 249 The function `buffer-substring-no-properties' is used instead.
 250 The argument STRING is ignored."
 251   (buffer-substring-no-properties
 252    (match-beginning num) (match-end num)))
 253
 254 (defun-mh mh-replace-regexp-in-string replace-regexp-in-string
 255   (regexp rep string &optional fixedcase literal subexp start)
 256   "Replace REGEXP with REP everywhere in STRING and return result.
 257 This function is used by XEmacs that lacks `replace-regexp-in-string'.
 258 The function `replace-in-string' is used instead.
 259 The arguments FIXEDCASE, SUBEXP, and START, used by
 260 `replace-in-string' are ignored."
 261   (replace-in-string string regexp rep literal))
 262
 263 ;; Copy of constant from url-util.el in Emacs 22; needed by Emacs 21.
 264 (if (not (boundp 'url-unreserved-chars))
 265     (defconst mh-url-unreserved-chars
 266       '(
 267         ?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
 268         ?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
 269         ?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9
 270         ?- ?_ ?. ?! ?~ ?* ?' ?\( ?\))
 271       "A list of characters that are _NOT_ reserved in the URL spec.
 272 This is taken from RFC 2396."))
 273
 274 (defun-mh mh-url-hexify-string url-hexify-string (str)
 275   "Escape characters in a string.
 276 This is a copy of `url-hexify-string' from url-util.el in Emacs
 277 22; needed by Emacs 21."
 278   (mapconcat
 279    (lambda (char)
 280      ;; Fixme: use a char table instead.
 281      (if (not (memq char mh-url-unreserved-chars))
 282          (if (> char 255)
 283                (error "Hexifying multibyte character %s" str)
 284            (format "%%%02X" char))
 285        (char-to-string char)))
 286    str ""))
 287
 288 (defun-mh mh-view-mode-enter
 289   view-mode-enter (&optional return-to exit-action)
 290   "Enter View mode.
 291 This function is used by XEmacs that lacks `view-mode-enter'.
 292 The function `view-mode' is used instead.
 293 The arguments RETURN-TO and EXIT-ACTION are ignored."
 294   ;; Shush compiler.
 295   (if return-to nil)
 296   (if exit-action nil)
 297   (view-mode 1))
 298
 299 (defmacro mh-write-file-functions ()
 300   "Return `write-file-functions' if it exists.
 301 Otherwise return `local-write-file-hooks'.
 302 This macro exists purely for compatibility. The former symbol is used
 303 in Emacs 22 onward while the latter is used in previous versions and
 304 XEmacs."
 305   (if (boundp 'write-file-functions)
 306       ''write-file-functions            ;Emacs 22 on
 307     ''local-write-file-hooks))          ;XEmacs
 308
 309 (provide 'mh-compat)
 310
 311 ;; Local Variables:
 312 ;; no-byte-compile: t
 313 ;; indent-tabs-mode: nil
 314 ;; sentence-end-double-space: nil
 315 ;; End:
 316
 317 ;; arch-tag: 577b0eab-a5cd-45e1-8d9f-c1a426f4d73c
 318 ;;; mh-compat.el ends here