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lisp/progmodes/octave-hlp.el

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+;; octave-hlp.el --- getting help on Octave symbols using info
+
+;;; Copyright (C) 1997 Free Software Foundation, Inc.
+
+;; Author: Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at>
+;; Author: John Eaton <jwe@bevo.che.wisc.edu>
+;; Maintainer: Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at>
+;; Keywords: languages
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 2, or (at your option)
+;; any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+
+;; Provides the command `octave-help' which allows index lookup of a
+;; symbol in the Octave-related info files, as specified by the list
+;; `octave-help-files'.
+
+;; Other features may be added in future versions.
+
+;;; Code:
+
+(require 'octave)
+(require 'info)
+
+(defvar octave-help-files '("octave")
+  "List of info files with documentation for Octave.
+Default is (\"octave\").")
+
+(defvar octave-help-lookup-alist nil
+  "Alist of Octave index entries for lookup.")
+
+(defvar octave-help-completion-alist nil
+  "Alist of Octave index entries for completion.
+The entries are of the form (VAR . VAR), where VAR runs through all
+different keys in `octave-help-lookup-alist'.")
+
+;;;###autoload
+(defun octave-help (key)
+  "Get help on Octave symbols from the Octave info files.
+Look up KEY in the function, operator and variable indices of the files
+specified by `octave-help-files'.
+If KEY is not a string, prompt for it with completion."
+  (interactive
+   (list
+    (completing-read (format "Describe Octave symbol: ")
+		     (octave-help-get-completion-alist)
+		     nil t)))
+  (if (get-buffer "*info*")
+      (set-buffer "*info*"))
+  (if (zerop (length key))
+      (Info-find-node (car octave-help-files) "Top")
+    (let ((alist (copy-alist (octave-help-get-lookup-alist)))
+	  entry matches)
+      (while (setq entry (car alist))
+	(if (string-match key (car entry))
+	    (add-to-list 'matches entry))
+	(setq alist (cdr alist)))
+      (if matches
+	  (progn
+	    (setq Info-index-alternatives matches)
+	    (Info-index-next 0))))))
+
+(defun octave-help-get-lookup-alist ()
+  "Build the index lookup alist from all Octave info files.
+The files specified by `octave-help-files' are searched."
+  (if octave-help-lookup-alist
+      ()
+    (message "Building help lookup alist...")    
+    (let ((files octave-help-files) file key node)
+      (save-window-excursion
+	(while files
+	  (setq file (car files))
+ 	  (Info-goto-node (concat "(" file ")"))
+	  (condition-case nil
+	      (progn
+		(Info-index "")
+		(while
+		    (progn
+		      (while (re-search-forward
+			      "^\\* \\([^(:]+\\)[^:]*: *\\(.+\\)\\.$"
+			      nil t)
+			(setq key (match-string 1)
+			      node (concat "(" file ")" (match-string 2)))
+			(and (string-match "\\(.*\\>\\) *$" key)
+			     (setq key (replace-match "\\1" t nil key)))
+			(add-to-list 'octave-help-lookup-alist
+				     (list key
+					   node
+					   (concat (concat "(" file ")")
+						   Info-current-node)
+					   0)))
+		      (and (setq node (Info-extract-pointer "next" t))
+			   (string-match
+			    (concat "\\(Function\\|Operator\\|Variable\\) "
+				    "\\<Index\\>")
+			    node)))
+		  (Info-goto-node node)))
+	    (error nil))
+	  (setq files (cdr files)))))
+    (message "Building help lookup alist...done"))
+  octave-help-lookup-alist)
+
+(defun octave-help-get-completion-alist ()
+  "Build the index completion alist from all Octave info files.
+The files specified by `octave-help-files' are searched."
+  (if octave-help-completion-alist
+      ()
+    (message "Building help completion alist...")
+    (let ((alist (octave-help-get-lookup-alist)) entry)
+      (while alist
+	(setq entry (car alist))
+	(add-to-list 'octave-help-completion-alist
+		     (cons (car entry) (car entry)))
+	(setq alist (cdr alist))))
+    (message "Building help completion alist...done"))    
+  octave-help-completion-alist)
+
+;;; octave-hlp.el ends here