Emacs python-mode: how to highlight str or unicode str in different colors

Question

I would like emacs to help me visually identify strings that have not been changed to unicode strings (python versions <3):

"display this string in color red" 

and

 u"display this string in color orange" 

using emacs 23 and python-mode

What do I need to add to my .emacs? Thanks.

Answer 1

In my version, u not highlighted, but a string. You need to be more creative than me about individuals. I just stole them from font-lock and changed almost everything to "red" .

If you also want to highlight u , you can put a text property in it in the py-font-lock-sytactic-face-function below. looking-back tells you where u . Now I'm just too lazy. Too late. It’s also a bit of “hacks.”

  (defface font-lock-ucs-string-face
   '((((class grayscale) (background light)): foreground "DarkGray": slant italic)
     (((class grayscale) (background dark)): foreground "DarkGray": slant italic)
     (((class color) (min-colors 88) (background light)): foreground "red")
     (((class color) (min-colors 88) (background dark)): foreground "red")
     (((class color) (min-colors 16) (background light)): foreground "red")
     (((class color) (min-colors 16) (background dark)): foreground "red")
     (((class color) (min-colors 8)): foreground "red")
     (t: slant italic))
   "Font Lock mode face used to highlight strings."
   : group 'font-lock-faces)


 (defun py-font-lock-syntactic-face-function (state)
   "See variable` font-lock-syntactic-face-function '"
   (message "Running py-font-lock-syntactic-face-function at% d." (point))
   (if (nth 3 state)
       (if (looking-back "u \" ")
       'font-lock-ucs-string-face
     'font-lock-string-face)
     'font-lock-comment-face))

 (add-hook 'python-mode-hook (lambda ()
                    (setq font-lock-syntactic-face-function
                      'py-font-lock-syntactic-face-function)))

Answer 2

I have something like the following in .emacs :

 (eval-after-load "python-mode" (add-hook 'python-mode-hook (lambda () (font-lock-add-keywords nil '(("[^\\w]\\(r\\|u\\)[\'\"]" (1 font-lock-keyword-face))))))) 

Which makes "u" (and "r") stand out, not the whole line. Perhaps this is enough or you can see a way to adapt it.

Answer 3

Yu Shen discusses a completely different case in the comments. The specified syntax is not parsed by a simple parser (see, for example, syntax-ppss ). You need to define one native font lock handler (preferably jit-lock ).

There is a particular problem in this task. It is necessary to determine when the user has finished entering the character, otherwise each part of the character will be registered in the dictionary and get its own color. The code below checks to see if the point is outside the character. If you enter a space after the character, the character lights up.

The code below is only an approximate implementation of one of the possible solutions. Other, perhaps better solutions exist.

  (defvar tag-font-lock-dict (make-hash-table: test 'equal)
   "Dictionary that assigns colors to tags.")
 (make-variable-buffer-local 'tag-font-lock-dict)

 (defvar tag-font-lock-re "# [[: alnum:]] + \\>"
   "Regular expression defining tags.")

 (defvar tag-font-lock-colors (apply 'vector (cdddr (defined-colors)))
   "Vector of available colors. We should be more selective here.")

 (defvar tag-font-lock-num-used-colors 0
   "Number of used colors.")
 (make-variable-buffer-local 'tag-font-lock-num-used-colors)

 (require 'cl)

 (defun tag-font-lock-next-color ()
   "Get the next color for a new tag."
   (prog1
       (aref tag-font-lock-colors tag-font-lock-num-used-colors)
     (setq tag-font-lock-num-used-colors
       (mod (1+ tag-font-lock-num-used-colors)
            (length tag-font-lock-colors)))))

 (defun tag-font-lock-handler (be)
   "Colorize tags in region from b to e."
   (let (col ol sym (pt (point)))
     (save-excursion
       (remove-overlays be 'tag-font-lock t) ;;  No danger of splitted overlays.  We have always full lines.
       (goto-char b)
       (while (re-search-forward tag-font-lock-re e 'noErr)
     (when (or (= pt (match-end 0)))
       (setq sym (match-string-no-properties 0)
         ol (make-overlay (match-beginning 0) (match-end 0))
         col (or (gethash sym tag-font-lock-dict)
             (puthash sym (tag-font-lock-next-color) tag-font-lock-dict)))
       (overlay-put ol 'face (list (list: foreground col)))
       (overlay-put ol 'tag-font-lock t)
       )))))

 (defun tag-font-lock-clear ()
   "Remove color from tags in current buffer."
   (interactive)
   (remove-overlays 0 (buffer-size) 'tag-font-lock t)
   (clrhash tag-font-lock-dict))

 (define-minor-mode tag-font-lock-mode
   "Highlight tags."
   : lighter "TH" ;;  stands for tag highlight
   (if tag-font-lock-mode
       (progn
     (setq font-lock-extend-region-functions' font-lock-extend-region-wholelines)
     (font-lock-mode 1)
     (jit-lock-register 'tag-font-lock-handler))
     (jit-lock-unregister 'tag-font-lock-handler)
     (tag-font-lock-clear)))