;;; ltx-help.el --- Lookup latex commands in info pages.
;; Authors: Peter Galbraith <rhogee@bathybius.meteo.mcgill.ca> or <galbrth@ac.dal.ca>
;; Christian Lynbech <lynbech@daimi.aau.dk>
;; Martin Sjolin <marsj@ida.liu.se>
;; Boris Goldowsky <boris@cs.rochester.edu>
;; Maintainer: as part of latexrefman, http://home.gna.org/latexrefman/
;; Updated: 25 April 2013
;; Keywords: help, latex, info
;;; Commentary:
;; Use the function latex-help to look up a latex command or
;; environment in the latex online manual. If point is at such a
;; command, this will be the default.
;; The Texinfo document that this code works with is at
;; http://ctan.org/pkg/latex2e-help-texinfo.
;; Installation:
;;
;; Add the following piece of code to your .emacs
;; (define-key help-map "\C-l" 'latex-help)
;;
;; to bind latex-help to C-h C-l. To load latex-help when loading AUC-TeX or
;; some other LaTeX/TeX mode and bind the it to C-C i key, add the the following
;; to you .emacs:
;;
;; (add-hook 'Latex-mode-hook
;; (function (lambda ()
;; (define-key LaTeX-mode-map "\C-ci" 'latex-help))))
;;
;; or if you do not have add-hook (a very nice package):
;;
;; (setq Latex-mode-hook
;; (function (lambda ()
;; (define-key LaTeX-mode-map "\C-ci" 'latex-help))))
;;
;;
;;; Change Log:
;;Mar 4, 1994 <lynbech@daimi.aau.dk>:
;; Changed to my personal preferences. I have changed the function
;; names. I have changed it to take a parameter, rather than just
;; taking the current word. I am also basing it on the index rather
;; than the node names.
;;
;;Mar 10, 1994 <marsj@ida.liu.se>:
;; Added definition of current-word if not present.
;; Made default value pick up a leading \ if apropriate
;;
;;Mar 11, 1994 <lynbech@daimi.aau.dk>:
;; Changed the name of current-word into latex-help-guess. This
;; eliminates the need for the embedded defun.
;; Also made describe-latex work more like describe-function in its
;; way of using default values. Now you must press return at an
;; empty prompt to get the listed default (if any).
;;
;;Mar 10, 1994 <marsj@ida.liu.se>:
;; Rewrote part of the describe-latex command to use the prefix
;; argument, changed latex-help-get-cmd-obarray to return the
;; the new array and test if it is empty or not. Add information
;; concerning where to find the latex.texi file and emacs 18 info.el
;;
;;Mar 28, 1994 <boris@cs.rochester.edu>:
;; * rewrote describe-latex's command-reading code; it did not
;; default correctly on my system.
;; * Added latex-help-hist, for completion history.
;; * Modified it to use show-temp-buffer, if defined, so that it will
;; display the help buffer in accord with user preferences.
;; * Renamed describe-latex to latex-help, for consistency with other names.
;; * Removed unneeded (interactive) specs for latex-help-guess and
;; latex-help-get-cmd-obarray.
;; * Added autoload cookies.
;; * Doc fix.
;;
;;Mar 29, 1994 <marsj@ida.liu.se>:
;; * made it working under epoch/emacs-18 by calling
;; completion-read without the last argument.
;; * made prompting similar to emacs help
;; * moved add-hook and define keys to installation section, since
;; the settings conflict with my own keybindings. Also, the key
;; binding should be chosen by the end user.
;;
;; Wed Mar 30 08:45:50 1994 LYNBECH
;; * Changed file layout to conform to FSF's standards
;; * Tweaked latex-help-guess to include any leading backslashes
;; * Inversed the meaning of the prefix argument. Now default is
;; to switch buffers. Also added new variable `latex-help-split-window'
;; to allow window splitting always.
;; * Minor doc fixes
;;
;; Wed Apr 6 08:34:08 1994 LYNBECH
;; * fixed latex-help-guess to be more faithful to the lexical rules
;; of TeX. The result is not especially elegant.
;;
;;Apr 16, 1994 <abraham@iesd.auc.dk>:
;; Changed the name to `ltx-help.el'.
;;
;; Sat Apr 1 1995 Torsten Martinsen (torsten@kom.auc.dk)
;; Changed obarray to an alist where the car of each cons cell is the
;; command name, and the cdr is the Info node describing that
;; command. This implementation has the following advantages:
;; - we don't need to have a lot of small redundant Info nodes; instead,
;; we can use the Texinfo function index mechanism.
;; - the alist is dynamically sized, so this version will work regardless
;; of how many LaTeX commands the Info file contains.
;; Added info on LaTeX2e Info file.
;;
;; Mon Apr 15 1996 Torsten Martinsen (bullestock@dk-online.dk)
;; Changed node 'List of Commands' to 'Command Index' as suggested by
;; Ralf Fassel <ralf@natlab.research.philips.com>.
;;
;; Mon Apr 22 1996 Torsten Martinsen (bullestock@dk-online.dk)
;; When running under FSF Emacs, use (buffer-substring-no-properties)
;; instead of (buffer-substring) as suggested by Kurt Hornik
;; <hornik@ci.tuwien.ac.at>. Also removed Emacs 18 support.
;;
;; Thu Jun 12 2008 Karl Berry (karl@freefriends.org)
;; Change latex-help-file to "(latex2e)", so our names are consistent.
;; Doc updates.
;;
;; Thu Apr 25 2013 Karl Berry (karl@freefriends.org)
;; Doc updates, and install these changes:
;;
;; Thu Apr 25 2013 Mandar Mitra (mandar.mitra@gmail.com)
;; Using with (for example) "array" goes to the top node
;; of latex2e.info instead of the intended node.
;;
;; Thu Dec 3 2015 Kevin Ryde (user42_kevin@yahoo.com.au)
;; * latex-help-get-cmd-alist don't take \:: as double-colon style index,
;; and allow "(line 123)" at the end of recent makeinfo output.
;; * Use buffer-substring-no-properties when exists (does in XEmacs 21.4).
;;; Code:
(require 'info)
(defalias 'ltxh-buffer-substring
(if (fboundp 'buffer-substring-no-properties) ;; when available
'buffer-substring-no-properties
'buffer-substring))
(defcustom latex-help-file "(latex2e)"
"Select the LaTeX2e non official reference manual translation."
:type '(choice
(string :tag "English" "(latex2e)")
(string :tag "French" "(latex2e-fr)")
(string :tag "Spanish" "(latex2e-es)") ))
(defvar latex-help-split-window nil
"*When this is non-nil, `latex-help' will always pop up the info
buffer, rather than just switch to it.")
(defvar latex-help-hist nil
"History for latex command help")
(defconst latex-help-cmd-alist nil
"Alist of the commands in the index of the latex info manual,
used for validation and completion.")
;;;###autoload
(defun latex-help (cmd split)
"Try to find info entry about LaTeX entity CMD.
CMD may be either a command or an environment.
If CMD is not a string, this function will prompt for it, eventually
with completion. If SPLIT (prefix arg.) is non-nil, latex-help will
pop up the Info buffer, rather than just switch to it. See also
variable `latex-help-split-window'."
(interactive
(list
(let* ((cw (latex-help-guess))
(cww (concat "\\" cw))
(cmd-alist (latex-help-get-cmd-alist))
(node (try-completion cw cmd-alist))
; try-completion returns actual string in case of partial match
; but returns t in case of exact match
(nodename1 (if (equal node t) cw node))
(nodename2 (if (equal nodename1 nil)
(try-completion cww cmd-alist) nodename1))
(guess (cond ((equal nodename2 t) cww)
((equal nodename2 nil) nil)
(t nodename2)))
(val (completing-read (if guess
(format "Describe LaTeX command (default %s): " guess)
"Describe LaTeX command: ")
cmd-alist nil t nil
'latex-help-hist)))
(cdr (assoc (if (equal val "")
guess
val) cmd-alist)))
current-prefix-arg))
(if (not (or split latex-help-split-window))
(Info-goto-node (concat latex-help-file cmd))
(save-excursion
(let ((pop-up-windows t)
(buffer (current-buffer)))
(pop-to-buffer nil)
(Info-goto-node (concat latex-help-file cmd))
(if (fboundp 'show-temp-buffer)
(show-temp-buffer (current-buffer) t)
(pop-to-buffer buffer))))))
(defun latex-help-guess ()
"Return the word point is on as a string, if it's between two
word-constituent characters. If not, but it immediately follows one,
move back first. Otherwise, if point precedes a word constituent,
move forward first. Otherwise, move backwards until a word constituent
is found and get that word; if you reach a newline first, move forward
instead.
This function has been tweaked to deal better with latex commands.
Return the LaTeX command point is on as a string.
"
;; cl: I am not claiming this to be neither elegant nor fast.
(save-excursion
(let ((oldpoint (point)) (start (point)) (end (point))
(wc "A-Za-z") (nwc "^A-Za-z"))
(cond
((looking-at "\\\\[^A-Za-z]")
(setq start (point)
end (+ 2 (point))))
((looking-at "\\\\[A-Za-z]+")
(setq start (match-beginning 0)
end (match-end 0)))
(t
(skip-chars-backward wc)
(skip-chars-backward "\\\\" (1- (point)))
(setq start (point))
(goto-char oldpoint)
(skip-chars-forward "\\\\" (1+ (point)))
(skip-chars-forward wc)
(setq end (point))
(if (and (eq start oldpoint) (eq end oldpoint))
(progn
(skip-chars-backward nwc
(save-excursion (beginning-of-line) (point)))
(if (eq (preceding-char) ?\n)
(progn
(skip-chars-forward nwc)
(setq start (point))
(skip-chars-forward "\\\\" (1+ (point)))
(skip-chars-forward wc)
(setq end (point)))
(setq end (point))
(skip-chars-backward wc)
(skip-chars-backward "\\\\" (1- (point)))
(setq start (point)))))
)
)
(ltxh-buffer-substring start end)))
)
(defun latex-help-get-cmd-alist ()
"Scoop up the commands in the index of the latex info manual.
The values are saved in `latex-help-cmd-alist' for speed."
;; mm, does it contain any cached entries
(if (not (assoc "\\begin" latex-help-cmd-alist))
(save-window-excursion
(setq latex-help-cmd-alist nil)
(Info-goto-node (concat latex-help-file "Command Index"))
(if (re-search-forward "::$" nil t)
(progn
(end-of-buffer)
(while (re-search-backward "^\\* \\(.+\\)::$" nil t)
(setq key (ltxh-buffer-substring (match-beginning 1) (match-end 1)))
(setq latex-help-cmd-alist
(cons (cons key key) latex-help-cmd-alist))))
(end-of-buffer)
(while (re-search-backward "^\\* \\(.+\\): *\\(.+\\)\\." nil t)
(setq key (ltxh-buffer-substring (match-beginning 1) (match-end 1)))
(setq value (ltxh-buffer-substring (match-beginning 2) (match-end 2)))
(setq latex-help-cmd-alist
(cons (cons key value) latex-help-cmd-alist))))
))
;; and return the alist.
latex-help-cmd-alist
)
(provide 'ltx-help)
;;; ltx-help.el ends here