lisp/docref.el

   1 ;;; docref.el --- Simple cross references for Elisp documentation strings
   2 ;; Copyright (C) 1994 Free Software Foundation, Inc.
   3
   4 ;; Author: Vadim Geshel <vadik@unas.cs.kiev.ua>
   5 ;; Created: 12 Jul 1994
   6 ;; Keywords: docs, help, lisp
   7 ;; original name was cross-ref.el.
   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
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  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
  23 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  24
  25 ;;; Commentary:
  26 ;;
  27 ;; This package allows you to use a simple form of cross references in
  28 ;; your Emacs Lisp documentation strings. Cross-references look like
  29 ;; \\(type@[label@]data), where type defines a method for retrieving
  30 ;; reference information, data is used by a method routine as an argument,
  31 ;; and label "represents" the reference in text. If label is absent, data
  32 ;; is used instead.
  33 ;;
  34 ;; Special reference labeled `back', when present, can be used to return
  35 ;; to the previous contents of help buffer.
  36 ;;
  37 ;; Cross-referencing currently is intended for use in doc strings only
  38 ;; and works only in temporary buffers (created by `with-output-to-temp-buffer').
  39 ;; List of temp buffers in which cross-referencing is to be active is specified
  40 ;; by variable DOCREF-BUFFERS-LIST, which contains only "*Help*" by default.
  41 ;;
  42 ;; Documentation strings for this package's functions and variables can serve
  43 ;; as examples of usage.
  44 ;;
  45 ;;; Customization:
  46 ;;
  47 ;; See source. The main customization variable is `docref-methods-alist'.
  48 ;; It consists of (type . function) pairs, where type is a string which
  49 ;; corresponds to type in cross-references and function is called with
  50 ;; one argument - reference `data' - when a reference is activated.
  51 ;;
  52 ;;; Installation:
  53 ;;
  54 ;; Place this file somewhere in your load-path, byte-compiled it, and add
  55 ;; (require 'cross-ref)
  56 ;; to your .emacs.
  57 \f
  58 ;;; Code:
  59
  60 ;; User customizable variables
  61
  62 (defvar docref-highlight-p t
  63   "*If non-nil, \\(f@docref-subst) highlights cross-references.
  64 Under window system it highlights them with face defined by
  65 \\(v@docref-highlight-face), on character terminal highlighted references
  66 look like cross-references in info mode.")
  67
  68 (defvar docref-highlight-face 'highlight
  69   "*Face used to highlight cross-references (used by \\(f@docref-subst))")
  70
  71 (defvar docref-methods-alist
  72   '(("f" . docref-describe-function)    ; reference to a function documentation
  73     ("v" . docref-describe-variable)    ; reference to a variable documentation
  74     ("F" . docref-read-file)            ; reference to a file contents
  75     ("s" . docref-use-string)           ; reference to a string
  76     ("V" . docref-use-variable-value)   ; reference to variable value
  77     ("0" . beep))                       ; just highlighted text
  78   "Alist which maps cross-reference ``types'' to retrieval functions.
  79
  80 The car of each element is a string that serves as `type' in cross-references.
  81 \(See \\(f@docref-subst)).  The cdr is a function of one argument,
  82 to be called to find this reference.")
  83
  84 (defvar docref-back-label "\nback"
  85   "Label to use by \\(f@docref-subst) for the go-back reference.")
  86
  87 (defvar docref-back-reference nil
  88   "If non-nil, this is a go-back reference to add to the current buffer.
  89 The value specifies how to go back.  It should be suitable for use
  90 as the second argument to \\(f@docref-insert-label).
  91 \\(f@docref-subst) uses this to set up the go-back reference.")
  92
  93 (defvar docref-last-active-buffer)
  94 \f
  95 ;;;###autoload
  96 (defun docref-setup ()
  97   "Process docref cross-references in the current buffer.
  98 See also \\(f@docref-subst)."
  99   (interactive)
 100   (docref-subst (current-buffer))
 101   (docref-mode))
 102
 103 (defvar docref-mode-map nil)
 104 (or docref-mode-map
 105     (let ((map (make-sparse-keymap)))
 106       (define-key map [mouse-2] 'docref-follow-mouse)
 107       (define-key map "\C-c\C-b" 'docref-go-back)
 108       (define-key map "\C-c\C-c" 'docref-follow)
 109       (setq docref-mode-map map)))
 110
 111 (defun docref-mode ()
 112   "Major mode for help buffers that contain cross references.
 113 To follow a reference, move to it and type \\[docref-follow], or use
 114 \\[docref-follow-mouse].  The command \\[docref-go-back] can used to go
 115 back to where you came from."
 116   (interactive)
 117   (kill-all-local-variables)
 118   (setq major-mode 'docref-mode)
 119   (setq mode-name "Docref")
 120   (use-local-map docref-mode-map)
 121   (run-hooks 'docref-mode))
 122 \f
 123 (defun docref-subst (buf)
 124   "Parse documentation cross-references in buffer BUF.
 125
 126 Find cross-reference information in a buffer and
 127 highlight them with face defined by \\(v@docref-highlight-face).
 128
 129 Cross-reference has the following format: \\ (TYPE[@LABEL]@DATA), where
 130 TYPE defines method used to retrieve xref data (like reading from file or
 131 calling \\(f@describe-function)), DATA is an argument to this method
 132 \(like file name or function name), and LABEL is displayed in text using
 133 \\(v@docref-highlight-face).
 134
 135 The special reference `back' can be used to return back.
 136 The variable \\(v@docref-back-label) specifies the label to use for that.
 137
 138 See \\(v@docref-methods-alist) for currently defined methods."
 139   (interactive "b")
 140   (save-excursion
 141     (set-buffer buf)
 142     (goto-char (point-min))
 143     ;; The docref-seen property indicates that we have processed this
 144     ;; buffer's contents already, so don't do it again.
 145     (if (not (get-text-property (point-min) 'docref-seen))
 146         (let ((old-modified (buffer-modified-p)))
 147           (while (re-search-forward "[\\](\\([^\)\@]+\\)\\(@[^\)\@]+\\)?@\\([^\)]*\\))"
 148                                     nil t)
 149             (let* ((start (match-beginning 0))
 150                    (type (buffer-substring (match-beginning 1) (match-end 1)))
 151                    (data (buffer-substring (match-beginning 3) (match-end 3)))
 152                    (label
 153                     (if (match-beginning 2)
 154                         (buffer-substring (+ (match-beginning 2) 1) (match-end 2))
 155                       data)))
 156               (replace-match "" t)
 157               (docref-insert-label label (cons type data))))
 158
 159           ;; Make a back-reference in this buffer, if desired.
 160           ;; (This is true if called from docref-follow.)
 161           (if docref-back-reference
 162               (progn
 163                 (goto-char (point-max))
 164                 (put-text-property (point-min) (1+ (point-min))
 165                                    'docref-back-position (point))
 166                 (docref-insert-label docref-back-label docref-back-reference)))
 167           (put-text-property (point-min) (1+ (point-min)) 'docref-seen t)
 168           (set-buffer-modified-p old-modified)))))
 169
 170 (defun docref-insert-label (string ref)
 171   (let ((label (concat string))
 172         (pos (point)))
 173     ;; decorate the label
 174     (let ((leading-space-end (save-match-data
 175                                (if (string-match "^\\([ \t\n]+\\)" label)
 176                                    (match-end 1)
 177                                  0)))
 178           (trailing-space-start (save-match-data
 179                                   (if (string-match "\\([ \t\n]+\\)$" label)
 180                                       (match-beginning 1)
 181                                     (length label)))))
 182       (if docref-highlight-p
 183           (if (not window-system)
 184               (setq label
 185                     (concat (substring label 0 leading-space-end)
 186                             "(*note "
 187                             (substring label leading-space-end trailing-space-start)
 188                             ")"
 189                             (substring label trailing-space-start)))
 190             ;; window-system
 191             (put-text-property leading-space-end
 192                                trailing-space-start
 193                                'face docref-highlight-face label)))
 194       (put-text-property 0 (length label) 'docref ref label)
 195       (insert label))))
 196 \f
 197 (defun docref-follow-mouse (click)
 198   "Follow the cross-reference that you click on."
 199   (interactive "e")
 200   (save-excursion
 201     (let* ((start (event-start click))
 202            (window (car start))
 203            (pos (car (cdr start)))
 204            (docref-last-active-buffer (current-buffer)))
 205       (set-buffer (window-buffer window))
 206       (docref-follow pos))))
 207
 208 (defun docref-go-back ()
 209   "Go back to the previous contents of help buffer."
 210   (interactive)
 211   (let ((pos (get-text-property (point-min) 'docref-back-position)))
 212     (if pos
 213         (docref-follow pos)
 214       (error "No go-back reference"))))
 215
 216 (defun docref-follow (&optional pos)
 217   "Follow cross-reference at point.
 218 For the cross-reference format, see \\(f@docref-subst).
 219 The special reference named `back' can be used to return back"
 220   (interactive)
 221   (or pos (setq pos (point)))
 222   (let ((docref-data (get-text-property pos 'docref)))
 223     (if docref-data
 224         ;; There is a reference at point.  Follow it.
 225         (let* ((type (car docref-data))
 226                (name (cdr docref-data))
 227                (method (assoc type docref-methods-alist))
 228                (cur-contents (buffer-string))
 229                (opoint (point))
 230                (docref-back-reference (cons "s" cur-contents))
 231                success)
 232           (if (null method)
 233               (error "Unknown cross-reference type: %s" type))
 234           (unwind-protect
 235               (save-excursion
 236                 (funcall (cdr method) name)
 237                 (setq success t))
 238             (or success
 239                 (progn
 240                   ;; (cdr method) got an error.
 241                   ;; Put back the text that we had.
 242                   (erase-buffer)
 243                   (insert cur-contents)
 244                   (goto-char opoint)))
 245             (set-buffer-modified-p nil))))))
 246 \f
 247 ;; Builtin methods for accessing a reference.
 248
 249 (defun docref-describe-function (data)
 250   (save-excursion
 251     (if (boundp 'docref-last-active-buffer)
 252         (set-buffer docref-last-active-buffer))
 253     (describe-function (intern data))))
 254
 255 (defun docref-describe-variable (data)
 256   (save-excursion
 257     (if (boundp 'docref-last-active-buffer)
 258         (set-buffer docref-last-active-buffer))
 259     (describe-variable (intern data))))
 260
 261 (defun docref-read-file (data)
 262   (with-output-to-temp-buffer (buffer-name)
 263     (erase-buffer)
 264     (insert-file-contents (expand-file-name data))))
 265
 266 (defun docref-use-string (data)
 267   (with-output-to-temp-buffer (buffer-name)
 268     (erase-buffer)
 269     (insert data)))
 270
 271 (defun docref-use-variable-value (data)
 272   (let ((sym (intern data)))
 273     (with-output-to-temp-buffer (buffer-name)
 274       (erase-buffer)
 275       (princ (symbol-value sym)))))
 276
 277 (provide 'docref)
 278
 279 ;;; docref.el ends here
 280