bug#10245: 23.3; handle Common Lisp :documentation strings

[Stefan Monnier <monnier@IRO.UMontreal.CA>]

> Several Common Lisp forms, such as defgeneric and defclass, support
> documentation strings following a :documentation keyword.

> Here's an example of a point class with documentation strings:

>   (defclass foo ()
>     ((x :reader x :initarg :x :documentation "X coordinate")
>      (y :reader y :initarg :y :documentation "Y coordinate"))
>     (:documentation "A point in the plane"))

> Emacs currently fontifies the documentation strings above using
> font-lock-string-face instead of font-lock-doc-face.

> The code below fixes the problem for me.  It is a refactoring of
> lisp-font-lock-syntactic-face-function in lisp/emacs-lisp/lisp-mode.el
> with the addition of a new function to detect documentation keywords.
> If lisp-font-lock-syntactic-face-function is replaced with the code
> below, Emacs fontifies strings after :documentation keywords using
> font-lock-doc-face.

Thanks.  This would be a welcomed addition, for 24.2 (24.1 is in testing
already so it's too late to add such features).  But I think it needs
a bit of massaging first, so that this new feature is not enabled in
emacs-lisp-mode.  E.g. I'd maybe change
lisp-font-lock-syntactic-face-function to
(run-hook-with-args-until-success 'lisp-string-in-doc-position-functions
state) and then add string-after-documentation-keyword-p to this hook
when in Common Lisp mode.  If you can provide such a thing as a patch
(i.e. output of "bzr diff" or "diff -u"), that would be even better.


        Stefan


> (defun string-in-doc-position-p (state)
>   (let* ((listbeg (nth 1 state))
>          (firstsym (and listbeg
>                         (save-excursion
>                           (goto-char listbeg)
>                           (and (looking-at "([ \t\n]*\\(\\(\\sw\\|\\s_\\)+\\)")
>                                (match-string 1)))))
>          (docelt (and firstsym (get (intern-soft firstsym)
>                                     lisp-doc-string-elt-property))))
>     (and docelt
>          ;; It's a string in a form that can have a docstring.
>          ;; Check whether it's in docstring position.
>          (save-excursion
>            (when (functionp docelt)
>              (goto-char (match-end 1))
>              (setq docelt (funcall docelt)))
>            (goto-char listbeg)
>            (forward-char 1)
>            (condition-case nil
>                (while (and (> docelt 0) (< (point) startpos)
>                            (progn (forward-sexp 1) t))
>                  (setq docelt (1- docelt)))
>              (error nil))
>            (and (zerop docelt) (<= (point) startpos)
>                 (progn (forward-comment (point-max)) t)
>                 (= (point) (nth 8 state)))))))

> (defun string-after-documentation-keyword-p (state)
>   (and (nth 1 state)                    ; we are inside a Lisp form
>        (let ((startpos (nth 8 state)))
>          (and startpos
>               (let ((ok nil)
>                     (prevsym (save-excursion
>                                (goto-char startpos)
>                                (condition-case nil
>                                    (progn (backward-sexp 1) (setf ok t))
>                                  (error nil))
>                                (and ok
>                                     (looking-at "\\(\\sw+\\)")
>                                     (match-string 1)))))
>                 (equal prevsym ":documentation"))))))

> (defun lisp-font-lock-syntactic-face-function (state)
>   (if (nth 3 state)
>       ;; This might be a (doc)string or a |...| symbol.
>       (let ((startpos (nth 8 state)))
>         (if (eq (char-after startpos) ?|)
>             ;; This is not a string, but a |...| symbol.
>             nil
>           (if (or (string-in-doc-position-p state)
>                   (string-after-documentation-keyword-p state))
>               font-lock-doc-face
>             font-lock-string-face)))
>     font-lock-comment-face))



> In GNU Emacs 23.3.1 (x86_64-unknown-linux-gnu)
>  of 2011-07-15 on paradicsom.nyc.corp.google.com
> configured using `configure  '--prefix' '/local/software/package/emacs-23.3.1' '--without-x''

> Important settings:
>   value of $LC_ALL: nil
>   value of $LC_COLLATE: nil
>   value of $LC_CTYPE: nil
>   value of $LC_MESSAGES: nil
>   value of $LC_MONETARY: nil
>   value of $LC_NUMERIC: nil
>   value of $LC_TIME: nil
>   value of $LANG: en_US.UTF-8
>   value of $XMODIFIERS: nil
>   locale-coding-system: utf-8-unix
>   default enable-multibyte-characters: t

> Major mode: Lisp Interaction

> Minor modes in effect:
>   file-name-shadow-mode: t
>   global-font-lock-mode: t
>   font-lock-mode: t
>   auto-encryption-mode: t
>   auto-compression-mode: t
>   line-number-mode: t

> Recent input:
> ESC [ > 1 ; 2 3 0 5 ; 0 c ESC x b u g - TAB ESC DEL 
> ESC DEL r e p o r t - TAB RET

> Recent messages:
> ("emacs")
> Loading /local/software/source-trees/emacs-jabber/jabber-autoloads.el (source)...done

> Load-path shadows:
> /local/software/source-trees/cc-mode/cc-fonts hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-fonts
> /local/software/source-trees/cc-mode/cc-align hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-align
> /local/software/source-trees/cc-mode/cc-menus hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-menus
> /local/software/source-trees/cc-mode/cc-engine hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-engine
> /local/software/source-trees/cc-mode/cc-mode hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-mode
> /local/software/source-trees/cc-mode/cc-awk hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-awk
> /local/software/source-trees/cc-mode/cc-defs hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-defs
> /local/software/source-trees/cc-mode/cc-vars hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-vars
> /local/software/source-trees/cc-mode/cc-styles hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-styles
> /local/software/source-trees/cc-mode/cc-bytecomp hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-bytecomp
> /local/software/source-trees/cc-mode/cc-compat hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-compat
> /local/software/source-trees/cc-mode/cc-cmds hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-cmds
> /local/software/source-trees/cc-mode/cc-langs hides /local/software/package/emacs-23.3.1/share/emacs/23.3/lisp/progmodes/cc-langs

> Features:
> (shadow sort mail-extr message ecomplete rfc822 mml easymenu mml-sec
> password-cache mm-decode mm-bodies mm-encode mailcap mail-parse rfc2231
> rfc2047 rfc2045 qp ietf-drums mailabbrev nnheader gnus-util netrc
> time-date mm-util mail-prsvr gmm-utils wid-edit mailheader canlock sha1
> hex-util hashcash mail-utils warnings emacsbug uniquify advice help-fns
> advice-preload slime-autoloads regexp-opt cl cl-19 ediff-hook vc-hooks
> lisp-float-type lisp-mode register page menu-bar rfn-eshadow timer
> jit-lock font-lock syntax facemenu font-core frame cham georgian
> utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
> japanese hebrew greek romanian slovak czech european ethiopic indian
> cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev
> loaddefs button minibuffer faces cus-face files text-properties overlay
> md5 base64 format env code-pages mule custom widget
> hashtable-print-readable backquote make-network-process multi-tty emacs)