rainbow-delimiters/rainbow-delimiters.el

;;; rainbow-delimiters.el --- Highlight nested parens, brackets, braces a different color at each depth.

;; Copyright (C) 2010-2011 Jeremy L. Rayman.
;; Author: Jeremy L. Rayman <jeremy.rayman@gmail.com>
;; Maintainer: Jeremy L. Rayman <jeremy.rayman@gmail.com>
;; Created: 2010-09-02
;; Version: 1.3.3
;; Keywords: faces, convenience, lisp, matching, tools, rainbow, rainbow parentheses, rainbow parens
;; EmacsWiki: http://www.emacswiki.org/emacs/RainbowDelimiters
;; Github: http://github.com/jlr/rainbow-delimiters
;; URL: http://www.emacswiki.org/emacs/download/rainbow-delimiters.el

;; This program 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 3 of the License, or
;; (at your option) any later version.

;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.


;;; Commentary:
;;
;; Rainbow-delimiters is a “rainbow parentheses”-like mode which highlights
;; parentheses, brackets, and braces according to their depth. Each
;; successive level is highlighted in a different color. This makes it easy
;; to spot matching delimiters, orient yourself in the code, and tell which
;; statements are at a given level.
;;
;; Great care has been taken to make this mode FAST. You should see no
;; discernible change in scrolling or editing speed while using it,
;; even in delimiter-rich languages like Clojure, Lisp, and Scheme.
;;
;; Default colors are subtle, with the philosophy that syntax highlighting
;; shouldn't being visually intrusive. Color schemes are always a matter
;; of taste.  If you take the time to design a new color scheme,
;; please share it (even a simple list of colors works) on the EmacsWiki
;; page or via github.
;; EmacsWiki: http://www.emacswiki.org/emacs/RainbowDelimiters
;; Github: http://github.com/jlr/rainbow-delimiters


;;; Installation:

;; 1. Place rainbow-delimiters.el on your emacs load-path.
;;
;; 2. Compile the file (necessary for speed):
;; M-x byte-compile-file <location of rainbow-delimiters.el>
;;
;; 3. Add the following to your dot-emacs/init file:
;; (require 'rainbow-delimiters)
;;
;; 4. Activate the mode in your init file.
;;    You can choose to enable it only in certain modes, or Emacs-wide:
;;
;; - To enable it only in specific modes, add lines like the following:
;; (add-hook 'clojure-mode-hook 'rainbow-delimiters-mode)
;;
;; - To activate the mode globally, add to your init file:
;; (global-rainbow-delimiters-mode)
;;
;; - To temporarily activate rainbow-delimiters mode in an open buffer:
;; M-x rainbow-delimiters-mode
;;
;; - To toggle global-rainbow-delimiters-mode:
;; M-x global-rainbow-delimiters-mode

;;; Customization:

;; To customize various options, including the color scheme:
;; M-x customize-group rainbow-delimiters
;;
;; color-theme.el users:
;; If you use the color-theme package, you can specify custom colors
;; by adding the appropriate faces to your theme.
;; - Faces take the form of:
;;   'rainbow-delimiters-depth-#-face' with # being the depth.
;;   Depth begins at 1, the outermost color.
;;   Faces exist for depths 1-9.
;; - The unmatched delimiter face (normally colored red) is:
;;   'rainbow-delimiters-unmatched-face'


;;; Change Log:

;; 1.0 - Initial release.
;; 1.1 - Stop tracking each delimiter's depth independently.
;;       This had lead to confusing results when viewing clojure
;;       code. Instead, just color based on current nesting inside
;;       all delimiters combined.
;;     - Added 'all-delimiters' faces to apply a color scheme to
;;       all delimiters at once. Other faces inherit from this group.
;; 1.1.1 - Change color scheme to a lighter, more subtle style.
;; 1.1.2: (2011-03-25)
;;  - Add an unmatched-delimiter face and correct problem with
;;    coloring of text following unmatched closing delims.
;; 1.2: (2011-03-28)
;;  - Unify delimiter faces: all delimiter types now use the same depth
;;    faces, of form 'rainbow-delimiters-depth-#-face'.
;; 1.2.1: (2011-03-29)
;;  - Conform to ELPA conventions.
;; 1.3: (2011-05-24)
;;  - Add separate color schemes for light and dark background modes.
;;  - Checkboxes to enable/disable highlighting for each delimiter type.
;;  - Improvements to Customize interface.
;;  - Infinite depth support by cycling through defined faces repeatedly.
;;  - Documentation changes.
;; 1.3.1 (2011-05-25)
;;  - Light color theme appears entirely grey on SRGB monitors. Revert to
;;    old color theme until a nicer light background theme can be added.
;;  - Correct typo in the installation step for users of dark backgrounds.
;; 1.3.2 (2011-10-14)
;;  - Add 'global-rainbow-delimiters-mode'.
;;  - Respect syntax of current buffer major-mode so delimiters
;;    highlight correctly in non-lisp languages.
;; 1.3.3 (2011-11-25)
;;  - Backwards compatibility with Emacs versions prior to 23.2.
;;    Defines "with-silent-modifications" if undefined.

;;; TODO:

;; - Add support for independent depth tracking of each delimiter type
;;   for users of C-like languages.
;; - Python style - increase depth with each new indentation.
;; - Add support for nested tags (XML, HTML)
;; - Set up proper example color-theme.el themes for rainbow-delimiters mode.
;; - Intelligent support for other languages: Ruby, LaTeX tags, et al.

;;; Issues:

;; - Rainbow-delimiters mode does not appear to change the color of
;;   delimiters when Org-mode is also enabled.


;;; Code:

(eval-when-compile (require 'cl))


;; Note: some of the functions in this file have been inlined for speed.
;; Inlining functions can cause problems with debugging. To debug these
;; functions more easily, change defsubst -> defun.
;; http://www.gnu.org/s/emacs/manual/html_node/elisp/Compilation-Tips.html

;;; Customize interface:

(defgroup rainbow-delimiters nil
  "Highlight nested parentheses, brackets, and braces according to their depth."
  :prefix "rainbow-delimiters-"
  :link '(url-link :tag "Website for rainbow-delimiters (EmacsWiki)"
                   "http://www.emacswiki.org/emacs/RainbowDelimiters")
  :group 'applications)

(defgroup rainbow-delimiters-faces nil
  "Faces for successively nested pairs of delimiters.

When depth exceeds innermost defined face, colors cycle back through."
  :tag "Color Scheme"
  :group 'rainbow-delimiters
  :link '(custom-group-link "rainbow-delimiters")
  :link '(custom-group-link :tag "Toggle Delimiters" "rainbow-delimiters-toggle-delimiter-highlighting")
  :prefix 'rainbow-delimiters-faces-)

;; Choose which delimiters you want to highlight in your preferred language:

(defgroup rainbow-delimiters-toggle-delimiter-highlighting nil
  "Choose which delimiters to highlight."
  :tag "Toggle Delimiters"
  :group 'rainbow-delimiters
  :link '(custom-group-link "rainbow-delimiters")
  :link '(custom-group-link :tag "Color Scheme" "rainbow-delimiters-faces"))

(defcustom rainbow-delimiters-highlight-parens-p t
  "Enable highlighting of nested parentheses -- ().

Non-nil (default) enables highlighting of parentheses.
Nil disables parentheses highlighting."
  :tag "Highlight Parentheses?"
  :type 'boolean
  :group 'rainbow-delimiters-toggle-delimiter-highlighting)

(defcustom rainbow-delimiters-highlight-brackets-p t
  "Enable highlighting of nested brackets -- [].

Non-nil (default) enables highlighting of brackets.
Nil disables bracket highlighting."
  :tag "Highlight Brackets?"
  :type 'boolean
  :group 'rainbow-delimiters-toggle-delimiter-highlighting)

(defcustom rainbow-delimiters-highlight-braces-p t
  "Enable highlighting of nested braces -- {}.

Non-nil (default) enables highlighting of braces.
Nil disables brace highlighting."
  :tag "Highlight Braces?"
  :type 'boolean
  :group 'rainbow-delimiters-toggle-delimiter-highlighting)


;;; Faces:

;; Unmatched delimiter face:
(defface rainbow-delimiters-unmatched-face
  '((((background light)) (:foreground "#88090B"))
    (((background dark)) (:foreground "#88090B")))
  "Face to highlight unmatched closing delimiters in."
  :group 'rainbow-delimiters-faces)

;; Faces for highlighting delimiters by nested level:
(defface rainbow-delimiters-depth-1-face
  '((((background light)) (:foreground "grey55"))
    (((background dark)) (:foreground "grey55")))
  "Nested delimiters face, depth 1 - outermost set."
  :tag "Rainbow Delimiters Depth 1 Face -- OUTERMOST"
  :group 'rainbow-delimiters-faces)

(defface rainbow-delimiters-depth-2-face
  '((((background light)) (:foreground "#93a8c6"))
    (((background dark)) (:foreground "#93a8c6")))
  "Nested delimiters face, depth 2."
  :group 'rainbow-delimiters-faces)

(defface rainbow-delimiters-depth-3-face
  '((((background light)) (:foreground "#b0b1a3"))
    (((background dark)) (:foreground "#b0b1a3")))
  "Nested delimiters face, depth 3."
  :group 'rainbow-delimiters-faces)

(defface rainbow-delimiters-depth-4-face
  '((((background light)) (:foreground "#97b098"))
    (((background dark)) (:foreground "#97b098")))
  "Nested delimiters face, depth 4."
  :group 'rainbow-delimiters-faces)

(defface rainbow-delimiters-depth-5-face
  '((((background light)) (:foreground "#aebed8"))
    (((background dark)) (:foreground "#aebed8")))
  "Nested delimiters face, depth 5."
  :group 'rainbow-delimiters-faces)

(defface rainbow-delimiters-depth-6-face
  '((((background light)) (:foreground "#b0b0b3"))
    (((background dark)) (:foreground "#b0b0b3")))
  "Nested delimiters face, depth 6."
  :group 'rainbow-delimiters-faces)

(defface rainbow-delimiters-depth-7-face
  '((((background light)) (:foreground "#90a890"))
    (((background dark)) (:foreground "#90a890")))
  "Nested delimiters face, depth 7."
  :group 'rainbow-delimiters-faces)

(defface rainbow-delimiters-depth-8-face
  '((((background light)) (:foreground "#a2b6da"))
    (((background dark)) (:foreground "#a2b6da")))
  "Nested delimiters face, depth 8."
  :group 'rainbow-delimiters-faces)

(defface rainbow-delimiters-depth-9-face
  '((((background light)) (:foreground "#9cb6ad"))
    (((background dark)) (:foreground "#9cb6ad")))
  "Nested delimiters face, depth 9."
  :group 'rainbow-delimiters-faces)

;;; Faces 10+:
;; NOTE: Currently unused. Additional faces for depths 9+ can be added on request.

(defconst rainbow-delimiters-max-face-count 9
  "Number of faces defined for highlighting delimiter levels.

Determines depth at which to cycle through faces again.")

;;; Face utility functions

(defsubst rainbow-delimiters-depth-face (depth)
  "Return face-name for DEPTH as a string 'rainbow-delimiters-depth-DEPTH-face'.

For example: 'rainbow-delimiters-depth-1-face'."
  (concat "rainbow-delimiters-depth-"
          (number-to-string
           (or
            ;; Our nesting depth has a face defined for it.
            (and (< depth rainbow-delimiters-max-face-count)
                 depth)
            ;; Deeper than # of defined faces; cycle back through to beginning.
            ;; Depth 1 face is only applied to the outermost delimiter pair.
            ;; Cycles infinitely through faces 2-9.
            (let ((cycled-depth (mod depth rainbow-delimiters-max-face-count)))
              (if (/= cycled-depth 0)
                  ;; Return face # that corresponds to current nesting level.
                  (mod depth rainbow-delimiters-max-face-count)
                ;; Special case: depth divides evenly into max, correct face # is max.
                rainbow-delimiters-max-face-count))))
          "-face"))


;;; Nesting level

(defvar rainbow-delimiters-syntax-table nil
  "Syntax table (inherited from buffer major-mode) which uses all delimiters.

When rainbow-delimiters-minor-mode is first activated, it sets this variable and
the other rainbow-delimiters specific syntax tables based on the current
major-mode. The syntax table is constructed by the function
'rainbow-delimiters-make-syntax-table'.")

;; syntax-table: used with syntax-ppss for determining current depth.
(defun rainbow-delimiters-make-syntax-table (syntax-table)
  "Inherit SYNTAX-TABLE and add delimiters intended to be highlighted by mode."
  (let ((table (copy-syntax-table syntax-table)))
    (modify-syntax-entry ?\( "()  " table)
    (modify-syntax-entry ?\) ")(  " table)
    (modify-syntax-entry ?\[ "(]" table)
    (modify-syntax-entry ?\] ")[" table)
    (modify-syntax-entry ?\{ "(}" table)
    (modify-syntax-entry ?\} "){" table)
    table))

(defun rainbow-delimiters-depth (loc)
  "Return # of nested levels of parens, brackets, braces LOC is inside of."
  (let ((depth
         (with-syntax-table rainbow-delimiters-syntax-table
           (car (syntax-ppss loc)))))
    (if (>= depth 0)
        depth
      0))) ; ignore negative depths created by unmatched closing parens.


;;; Text properties

;; Backwards compatibility: Emacs < v23.2 lack macro 'with-silent-modifications'.
(eval-and-compile
  (unless (fboundp 'with-silent-modifications)
    (defmacro with-silent-modifications (&rest body)
      "Defined by rainbow-delimiters.el for backwards compatibility with Emacs < 23.2.
 Execute BODY, pretending it does not modify the buffer.
If BODY performs real modifications to the buffer's text, other
than cosmetic ones, undo data may become corrupted.

This macro will run BODY normally, but doesn't count its buffer
modifications as being buffer modifications.  This affects things
like buffer-modified-p, checking whether the file is locked by
someone else, running buffer modification hooks, and other things
of that nature.

Typically used around modifications of text-properties which do
not really affect the buffer's content."
      (declare (debug t) (indent 0))
      (let ((modified (make-symbol "modified")))
        `(let* ((,modified (buffer-modified-p))
                (buffer-undo-list t)
                (inhibit-read-only t)
                (inhibit-modification-hooks t)
                deactivate-mark
                ;; Avoid setting and removing file locks and checking
                ;; buffer's uptodate-ness w.r.t the underlying file.
                buffer-file-name
                buffer-file-truename)
           (unwind-protect
               (progn
                 ,@body)
             (unless ,modified
               (restore-buffer-modified-p nil))))))))

(defsubst rainbow-delimiters-propertize-delimiter (loc depth)
  "Highlight a single delimiter at LOC according to DEPTH.

LOC is the location of the character to add text properties to.
DEPTH is the nested depth at LOC, which determines the face to use.

Sets text properties:
`font-lock-face' to the appropriate delimiter face.
`rear-nonsticky' to prevent color from bleeding into subsequent characters typed by the user."
  (with-silent-modifications
    (let ((delim-face (if (<= depth 0)
                          "rainbow-delimiters-unmatched-face"
                        (rainbow-delimiters-depth-face depth))))
      ;; (when (eq depth -1) (message "Unmatched delimiter at char %s." loc))
      (add-text-properties loc (1+ loc)
                           `(font-lock-face ,delim-face
                             rear-nonsticky t)))))


(defsubst rainbow-delimiters-unpropertize-delimiter (loc)
  "Remove text properties set by rainbow-delimiters mode from char at LOC."
  (with-silent-modifications
    (remove-text-properties loc (1+ loc)
                            '(font-lock-face nil
                              rear-nonsticky nil))))


(defun rainbow-delimiters-char-ineligible-p (loc)
  "Return t if char at LOC should be skipped, e.g. if inside a comment.

Returns t if char at loc meets one of the following conditions:
- Inside a string.
- Inside a comment.
- Is an escaped char, e.g. ?\)"
  (let ((parse-state (syntax-ppss loc)))
    (or
     (nth 3 parse-state)                ; inside string?
     (nth 4 parse-state)                ; inside comment?
     (and (eq (char-before loc) ?\\)  ; escaped char, e.g. ?\) - not counted
          (and (not (eq (char-before (1- loc)) ?\\)) ; special-case: ignore ?\\
               (eq (char-before (1- loc)) ?\?))))))
;; NOTE: standard char read syntax '?)' is not tested for because emacs manual
;; states punctuation such as delimiters should _always_ use escaped '?\)' form.


(defsubst rainbow-delimiters-apply-color (delim depth loc)
  "Apply color for DEPTH to DELIM at LOC following user settings.

DELIM is a string specifying delimiter type.
DEPTH is the delimiter depth, or corresponding face # if colors are repeating.
LOC is location of character (delimiter) to be colorized."
  (and
   ;; Ensure user has enabled highlighting of this delimiter type.
   (symbol-value (intern-soft
                  (concat "rainbow-delimiters-highlight-" delim "s-p")))
   (rainbow-delimiters-propertize-delimiter loc
                                            depth)))


;;; JIT-Lock functionality

;; Used to skip delimiter-by-delimiter `rainbow-delimiters-propertize-region'.
(defvar rainbow-delimiters-delim-regex "\\(\(\\|\)\\|\\[\\|\\]\\|\{\\|\}\\)"
  "Regex matching all opening and closing delimiters the mode highlights.")

;; main function called by jit-lock:
(defun rainbow-delimiters-propertize-region (start end)
  "Highlight delimiters in region between START and END.

Used by jit-lock for dynamic highlighting."
  (save-excursion
    (goto-char start)
    ;; START can be anywhere in buffer; determine the nesting depth at START loc
    (let ((depth (rainbow-delimiters-depth start)))
      (while (and (< (point) end)
                  (re-search-forward rainbow-delimiters-delim-regex end t))
        (backward-char) ; re-search-forward places point after delim; go back.
        (unless (rainbow-delimiters-char-ineligible-p (point))
          (let ((delim (char-after (point))))
            (cond ((eq ?\( delim)       ; (
                   (setq depth (1+ depth))
                   (rainbow-delimiters-apply-color "paren" depth (point)))
                  ((eq ?\) delim)       ; )
                   (rainbow-delimiters-apply-color "paren" depth (point))
                   (setq depth (or (and (<= depth 0) 0) ; unmatched paren
                                   (1- depth))))
                  ((eq ?\[ delim)       ; [
                   (setq depth (1+ depth))
                   (rainbow-delimiters-apply-color "bracket" depth (point)))
                  ((eq ?\] delim)       ; ]
                   (rainbow-delimiters-apply-color "bracket" depth (point))
                   (setq depth (or (and (<= depth 0) 0) ; unmatched bracket
                                   (1- depth))))
                  ((eq ?\{ delim)       ; {
                   (setq depth (1+ depth))
                   (rainbow-delimiters-apply-color "brace" depth (point)))
                  ((eq ?\} delim)       ; }
                   (rainbow-delimiters-apply-color "brace" depth (point))
                   (setq depth (or (and (<= depth 0) 0) ; unmatched brace
                                   (1- depth)))))))
        ;; move past delimiter so re-search-forward doesn't pick it up again
        (forward-char)))))

(defun rainbow-delimiters-unpropertize-region (start end)
  "Remove highlighting from delimiters between START and END."
  (save-excursion
    (goto-char start)
    (while (and (< (point) end)
                (re-search-forward rainbow-delimiters-delim-regex end t))
      ;; re-search-forward places point 1 further than the delim matched:
      (rainbow-delimiters-unpropertize-delimiter (1- (point))))))


;;; Minor mode:

;;;###autoload
(define-minor-mode rainbow-delimiters-mode
  "Highlight nested parentheses, brackets, and braces according to their depth."
  nil "" nil ; No modeline lighter - it's already obvious when the mode is on.
  (if (not rainbow-delimiters-mode)
      (progn
        (jit-lock-unregister 'rainbow-delimiters-propertize-region)
        (rainbow-delimiters-unpropertize-region (point-min) (point-max)))
    (jit-lock-register 'rainbow-delimiters-propertize-region t)
    ;; Create necessary syntax tables inheriting from current major-mode.
    (set (make-local-variable 'rainbow-delimiters-syntax-table)
         (rainbow-delimiters-make-syntax-table (syntax-table)))))

;;;###autoload
(defun rainbow-delimiters-mode-enable ()
  (rainbow-delimiters-mode 1))

;;;###autoload
(define-globalized-minor-mode global-rainbow-delimiters-mode
  rainbow-delimiters-mode rainbow-delimiters-mode-enable)

(provide 'rainbow-delimiters)

;;; rainbow-delimiters.el ends here.