;;; yasnippet.el --- Yet another snippet extension for Emacs.

;; Copyright 2008 pluskid

;; 

;; Author: pluskid <pluskid@gmail.com>

;; Version: 0.5.2

;; X-URL: http://code.google.com/p/yasnippet/

;; This file 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.

;; This file 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:

;; Basic steps to setup:

;;   1. Place `yasnippet.el' in your `load-path'.

;;   2. In your .emacs file:

;;        (require 'yasnippet)

;;   3. Place the `snippets' directory somewhere. E.g: ~/.emacs.d/snippets

;;   4. In your .emacs file

;;        (yas/initialize)

;;        (yas/load-directory "~/.emacs.d/snippets")

;;

;; For more information and detailed usage, refer to the project page:

;;      http://code.google.com/p/yasnippet/

(require 'cl)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; User customizable variables

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defvar yas/key-syntaxes (list "w" "w_" "w_." "^ ")

  "A list of syntax of a key. This list is tried in the order

to try to find a key. For example, if the list is '(\"w\" \"w_\").

And in emacs-lisp-mode, where \"-\" has the syntax of \"_\":

foo-bar

will first try \"bar\", if not found, then \"foo-bar\" is tried.")

(defvar yas/root-directory nil

  "The (list of) root directory that stores the snippets for each 

major modes.")

(defvar yas/indent-line t

  "Each (except the 1st) line of the snippet template is indented to

current column if this variable is non-`nil'.")

(make-variable-buffer-local 'yas/indent-line)

(defvar yas/trigger-key (kbd "TAB")

  "The key to bind as a trigger of snippet.")

(defvar yas/next-field-key (kbd "TAB")

  "The key to navigate to next field.")

(defvar yas/keymap (make-sparse-keymap)

  "The keymap of snippet.")

(define-key yas/keymap yas/next-field-key 'yas/next-field-group)

(define-key yas/keymap (kbd "S-TAB") 'yas/prev-field-group)

(define-key yas/keymap (kbd "<S-iso-lefttab>") 'yas/prev-field-group)

(define-key yas/keymap (kbd "<S-tab>") 'yas/prev-field-group)

(define-key yas/keymap (kbd "<backtab>") 'yas/prev-field-group)

(defvar yas/show-all-modes-in-menu nil

  "Currently yasnippet only all \"real modes\" to menubar. For

example, you define snippets for \"cc-mode\" and make it the

parent of `c-mode', `c++-mode' and `java-mode'. There's really

no such mode like \"cc-mode\". So we don't show it in the yasnippet

menu to avoid the menu becoming too big with strange modes. The

snippets defined for \"cc-mode\" can still be accessed from

menu-bar->c-mode->parent (or c++-mode, java-mode, all are ok).

However, if you really like to show all modes in the menu, set

this variable to t.")

(defvar yas/use-menu t

  "If this is set to `t', all snippet template of the current

mode will be listed under the menu \"yasnippet\".")

(defvar yas/trigger-symbol " =>"

  "The text that will be used in menu to represent the trigger.")

(defface yas/field-highlight-face

  '((((class color) (background light)) (:background "DarkSeaGreen2"))

    (t (:background "DimGrey")))

  "The face used to highlight a field of snippet.")

(defface yas/mirror-highlight-face

  '((((class color) (background light)) (:background "LightYellow2"))

    (t (:background "gray22")))

  "The face used to highlight mirror fields of a snippet.")

(defvar yas/window-system-popup-function #'yas/dropdown-list-popup-for-template

  "When there's multiple candidate for a snippet key. This function

is called to let user select one of them. `yas/text-popup-function'

is used instead when not in a window system.")

(defvar yas/text-popup-function #'yas/dropdown-list-popup-for-template

  "When there's multiple candidate for a snippet key. If not in a

window system, this function is called to let user select one of

them. `yas/window-system-popup-function' is used instead when in

a window system.")

(defvar yas/extra-mode-hooks

  '(ruby-mode-hook actionscript-mode-hook)

  "A list of mode-hook that should be hooked to enable yas/minor-mode.

Most modes need no special consideration. Some mode (like ruby-mode)

doesn't call `after-change-major-mode-hook' need to be hooked explicitly.")

(defvar yas/after-exit-snippet-hook

  '()

  "Hooks to run after a snippet exited.

The hooks will be run in an environment where some variables bound to 

proper values:

 * yas/snippet-beg : The beginning of the region of the snippet.

 * yas/snippet-end : Similar to beg.")

(defvar yas/before-expand-snippet-hook

  '()

  "Hooks to run after a before expanding a snippet.")

(defvar yas/buffer-local-condition 

  '(if (and (not (bobp))

	    (or (equal "font-lock-comment-face"

		       (get-char-property (1- (point))

					  'face))

		(equal "font-lock-string-face"

		       (get-char-property (1- (point))

					  'face))))

       '(require-snippet-condition . force-in-comment)

     t)

  "Condition to yasnippet local to each buffer.

    * If yas/buffer-local-condition evaluate to nil, snippet

      won't be expanded.

    * If it evaluate to the a cons cell where the car is the

      symbol require-snippet-condition and the cdr is a

      symbol (let's call it requirement):

       * If the snippet has no condition, then it won't be

         expanded.

       * If the snippet has a condition but evaluate to nil or

         error occured during evaluation, it won't be expanded.

       * If the snippet has a condition that evaluate to

         non-nil (let's call it result):

          * If requirement is t, the snippet is ready to be

            expanded.

          * If requirement is eq to result, the snippet is ready

            to be expanded.

          * Otherwise the snippet won't be expanded.

    * If it evaluate to other non-nil value:

       * If the snippet has no condition, or has a condition that

         evaluate to non-nil, it is ready to be expanded.

       * Otherwise, it won't be expanded.

Here's an example:

 (add-hook 'python-mode-hook

           '(lambda ()

              (setq yas/buffer-local-condition

                    '(if (python-in-string/comment)

                         '(require-snippet-condition . force-in-comment)

                       t))))")

(defvar yas/fallback-behavior 'call-other-command

  "The fall back behavior of YASnippet when it can't find a snippet

to expand. 

 * 'call-other-command means try to temporarily disable

    YASnippet and call other command bound to `yas/trigger-key'.

 * 'return-nil means return nil.")

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Internal variables

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defvar yas/version "0.5.2")

(defvar yas/snippet-tables (make-hash-table)

  "A hash table of snippet tables corresponding to each major-mode.")

(defvar yas/menu-table (make-hash-table)

  "A hash table of menus of corresponding major-mode.")

(defvar yas/menu-keymap (make-sparse-keymap "YASnippet"))

;; empty menu will cause problems, so we insert some items

(define-key yas/menu-keymap [yas/about]

  '(menu-item "About" yas/about))

(define-key yas/menu-keymap [yas/reload]

  '(menu-item "Reload all snippets" yas/reload-all))

(define-key yas/menu-keymap [yas/load]

  '(menu-item "Load snippets..." yas/load-directory))

(define-key yas/menu-keymap [yas/separator]

  '(menu-item "--"))

(defvar yas/known-modes

  '(ruby-mode rst-mode)

  "A list of mode which is well known but not part of emacs.")

(defconst yas/escape-backslash

  (concat "YASESCAPE" "BACKSLASH" "PROTECTGUARD"))

(defconst yas/escape-dollar

  (concat "YASESCAPE" "DOLLAR" "PROTECTGUARD"))

(defconst yas/escape-backquote

  (concat "YASESCAPE" "BACKQUOTE" "PROTECTGUARD"))

(defconst yas/field-regexp

  (concat "$\\([0-9]+\\)" "\\|"

	  "${\\(?:\\([0-9]+\\):\\)?\\([^}]*\\)}"))

(defvar yas/snippet-id-seed 0

  "Contains the next id for a snippet")

(defun yas/snippet-next-id ()

  (let ((id yas/snippet-id-seed))

    (incf yas/snippet-id-seed)

    id))

(defvar yas/overlay-modification-hooks

  (list 'yas/overlay-modification-hook)

  "The list of hooks to the overlay modification event.")

(defvar yas/overlay-insert-in-front-hooks

  (list 'yas/overlay-insert-in-front-hook)

  "The list of hooks of the overlay inserted in front event.")

(defvar yas/keymap-overlay-modification-hooks

  (list 'yas/overlay-maybe-insert-behind-hook)

  "The list of hooks of the big keymap overlay modification event.")

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; YASnippet minor mode

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defvar yas/minor-mode-map (make-sparse-keymap)

  "The keymap of yas/minor-mode")

(defvar yas/minor-mode-on-hook nil

  "Hook to call when yas/minor-mode is on.")

(defvar yas/minor-mode-off-hook nil

  "Hook to call when yas/minor-mode is off.")

(define-minor-mode yas/minor-mode

  "Toggle YASnippet mode.

With no argument, this command toggles the mode.

positive prefix argument turns on the mode.

Negative prefix argument turns off the mode.

When YASnippet mode is enabled, the TAB key

expands snippets of code depending on the mode.

You can customize the key through `yas/trigger-key'."

  ;; The initial value.

  nil

  ;; The indicator for the mode line.

  " yas"

  :group 'editing

  (define-key yas/minor-mode-map yas/trigger-key 'yas/expand))

(defun yas/minor-mode-on ()

  "Turn on YASnippet minor mode."

  (interactive)

  (yas/minor-mode 1))

(defun yas/minor-mode-off ()

  "Turn off YASnippet minor mode."

  (interactive)

  (yas/minor-mode -1))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Internal Structs

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defstruct (yas/template (:constructor yas/make-template

				       (content name condition)))

  "A template for a snippet."

  content

  name

  condition)

(defstruct (yas/snippet (:constructor yas/make-snippet ()))

  "A snippet."

  (groups nil)

  (exit-marker nil)

  (id (yas/snippet-next-id) :read-only t)

  (overlay nil))

(defstruct (yas/group (:constructor yas/make-group (primary-field snippet)))

  "A group contains a list of field with the same number."

  primary-field

  (fields (list primary-field))

  (next nil)

  (prev nil)

  snippet)

(defstruct (yas/field 

	    (:constructor yas/make-field (overlay number value transform)))

  "A field in a snippet."

  overlay

  number

  transform

  value)

(defstruct (yas/snippet-table (:constructor yas/make-snippet-table ()))

  "A table to store snippets for a perticular mode."

  (hash (make-hash-table :test 'equal))

  (parent nil))

(defun yas/snippet-valid? (snippet)

  "See if snippet is valid (ie. still alive)."

  (and (not (null snippet))

       (not (null (yas/snippet-overlay snippet)))

       (not (null (overlay-start (yas/snippet-overlay snippet))))))

(defun yas/snippet-add-field (snippet field)

  "Add FIELD to SNIPPET."

  (let ((group (find field

		     (yas/snippet-groups snippet)

		     :test

		     '(lambda (field group)

			(and (not (null (yas/field-number field)))

			     (not (null (yas/group-number group)))

			     (= (yas/field-number field)

				(yas/group-number group)))))))

    (if group

	(yas/group-add-field group field)

      (push (yas/make-group field snippet)

	    (yas/snippet-groups snippet)))))

(defun yas/group-value (group)

  "Get the default value of the field group."

  (or (yas/field-value

       (yas/group-primary-field group))

      ""))

(defun yas/group-number (group)

  "Get the number of the field group."

  (yas/field-number

   (yas/group-primary-field group)))

(defun yas/group-add-field (group field)

  "Add a field to the field group. If the value of the primary 

field is nil and that of the field is not nil, the field is set

as the primary field of the group."

  (push field (yas/group-fields group))

  (when (and (null (yas/field-value (yas/group-primary-field group)))

	     (yas/field-value field))

    (setf (yas/group-primary-field group) field)))

(defun yas/snippet-field-compare (field1 field2)

  "Compare two fields. The field with a number is sorted first.

If they both have a number, compare through the number. If neither

have, compare through the start point of the overlay."

  (let ((n1 (yas/field-number field1))

	(n2 (yas/field-number field2)))

    (if n1

	(if n2

	    (< n1 n2)

	  t)

      (if n2

	  nil

	(< (overlay-start (yas/field-overlay field1))

	   (overlay-start (yas/field-overlay field2)))))))

(defun yas/template-condition-predicate (condition)

  (condition-case err

      (save-excursion

	(save-restriction

	  (save-match-data

	    (eval condition))))

    (error (progn

	     (message (format "[yas]error in condition evaluation: %s"

			      (error-message-string err)))

	     nil))))

(defun yas/filter-templates-by-condition (templates)

  "Filter the templates using the condition. The rules are:

 * If the template has no condition, it is kept.

 * If the template's condition eval to non-nil, it is kept.

 * Otherwise (eval error or eval to nil) it is filtered."

  (remove-if '(lambda (pair)

		(let ((condition (yas/template-condition (cdr pair))))

		  (if (null condition)

		      (if yas/require-template-condition

			  t

			nil)

		    (let ((result 

			   (yas/template-condition-predicate condition)))

		      (if (eq yas/require-template-condition t)

			  result

			(not (eq result yas/require-template-condition)))))))

	     templates))

(defun yas/snippet-table-fetch (table key)

  "Fetch a snippet binding to KEY from TABLE. If not found,

fetch from parent if any."

  (let ((templates (yas/filter-templates-by-condition

		    (gethash key (yas/snippet-table-hash table)))))

    (when (and (null templates)

	       (not (null (yas/snippet-table-parent table))))

      (setq templates (yas/snippet-table-fetch

		       (yas/snippet-table-parent table)

		       key)))

    templates))

(defun yas/snippet-table-store (table full-key key template)

  "Store a snippet template in the table."

  (puthash key

	   (yas/modify-alist (gethash key

				      (yas/snippet-table-hash table))

			     full-key

			     template)

	   (yas/snippet-table-hash table)))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Internal functions

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun yas/ensure-minor-mode-priority ()

  "Ensure that the key binding of yas/minor-mode takes priority."

  (unless (eq 'yas/minor-mode

	      (caar minor-mode-map-alist))

    (setq minor-mode-map-alist

	  (cons

	   (cons 'yas/minor-mode yas/minor-mode-map)

	   (assq-delete-all 'yas/minor-mode

			    minor-mode-map-alist)))))

(defun yas/real-mode? (mode)

  "Try to find out if MODE is a real mode. The MODE bound to

a function (like `c-mode') is considered real mode. Other well

known mode like `ruby-mode' which is not part of Emacs might

not bound to a function until it is loaded. So yasnippet keeps

a list of modes like this to help the judgement."

  (or (fboundp mode)

      (find mode yas/known-modes)))

(defun yas/eval-string (string)

  "Evaluate STRING and convert the result to string."

  (condition-case err

      (save-excursion

	(save-restriction

	  (save-match-data

	    (format "%s" (eval (read string))))))

    (error (format "(error in elisp evaluation: %s)" 

		   (error-message-string err)))))

(defun yas/calculate-field-value (field value)

  "Calculate the value of the field. If there's a transform

for this field, apply it. Otherwise, the value is returned

unmodified."

  (let ((text value)

	(transform (yas/field-transform field)))

    (if transform

	(yas/eval-string transform)

      text)))

(defsubst yas/replace-all (from to)

  "Replace all occurance from FROM to TO."

  (goto-char (point-min))

  (while (search-forward from nil t)

    (replace-match to t t)))

(defun yas/snippet-table (mode)

  "Get the snippet table corresponding to MODE."

  (let ((table (gethash mode yas/snippet-tables)))

    (unless table

      (setq table (yas/make-snippet-table))

      (puthash mode table yas/snippet-tables))

    table))

(defsubst yas/current-snippet-table ()

  "Get the snippet table for current major-mode."

  (yas/snippet-table major-mode))

(defun yas/menu-keymap-for-mode (mode)

  "Get the menu keymap correspondong to MODE."

  (let ((keymap (gethash mode yas/menu-table)))

    (unless keymap

      (setq keymap (make-sparse-keymap))

      (puthash mode keymap yas/menu-table))

    keymap))

(defun yas/current-key ()

  "Get the key under current position. A key is used to find

the template of a snippet in the current snippet-table."

  (let ((start (point))

	(end (point))

	(syntaxes yas/key-syntaxes)

	syntax done templates)

    (while (and (not done) syntaxes)

      (setq syntax (car syntaxes))

      (setq syntaxes (cdr syntaxes))

      (save-excursion

	(skip-syntax-backward syntax)

	(setq start (point)))

      (setq templates

	    (yas/snippet-table-fetch

	     (yas/current-snippet-table)

	     (buffer-substring-no-properties start end)))

      (if templates

	  (setq done t)

	(setq start end)))

    (list templates

	  start

	  end)))

(defun yas/synchronize-fields (field-group)

  "Update all fields' text according to the primary field."

  (when (yas/snippet-valid? (yas/group-snippet field-group))

    (save-excursion

      (let* ((inhibit-modification-hooks t)

	     (primary (yas/group-primary-field field-group))

	     (primary-overlay (yas/field-overlay primary))

	     (text (buffer-substring-no-properties (overlay-start primary-overlay)

						   (overlay-end primary-overlay))))

	(dolist (field (yas/group-fields field-group))

	  (let* ((field-overlay (yas/field-overlay field))

		 (original-length (- (overlay-end field-overlay)

				     (overlay-start field-overlay))))

	    (unless (eq field-overlay primary-overlay)

	      (goto-char (overlay-start field-overlay))

	      (insert (yas/calculate-field-value field text))

	      (if (= (overlay-start field-overlay)

		     (overlay-end field-overlay))

		  (move-overlay field-overlay

				(overlay-start field-overlay)

				(point))

		(delete-char original-length)))))))))

(defun yas/overlay-modification-hook (overlay after? beg end &optional length)

  "Modification hook for snippet field overlay."

  (when (and after? (not undo-in-progress))

    (yas/synchronize-fields (overlay-get overlay 'yas/group))))

(defun yas/overlay-insert-in-front-hook (overlay after? beg end &optional length)

  "Hook for snippet overlay when text is inserted in front of a snippet field."

  (when after?

    (let ((field-group (overlay-get overlay 'yas/group))

	  (inhibit-modification-hooks t))

      (when (not (overlay-get overlay 'yas/modified?))

	(overlay-put overlay 'yas/modified? t)

	(when (> (overlay-end overlay) end)

	  (save-excursion

	    (goto-char end)

	    (delete-char (- (overlay-end overlay) end)))))

     (yas/synchronize-fields field-group))))

(defun yas/overlay-maybe-insert-behind-hook (overlay after? beg end &optional length)

  "Insert behind hook sometimes doesn't get called. I don't know why.

So I add modification hook in the big overlay and try to detect `insert-behind'

event manually."

  (when after?

    (cond ((and (= beg end)

		(> length 0)

		(= (overlay-start overlay)

		   (overlay-end overlay)))

	   (yas/exit-snippet (overlay-get overlay 'yas/snippet-reference)))

	  ((and (= length 0)

		(> end beg)

		(null (yas/current-snippet-overlay beg))

		(not (bobp)))

	   (let ((field-overlay (yas/current-snippet-overlay (1- beg))))

	     (if field-overlay

		 (when (= beg (overlay-end field-overlay))

		   (move-overlay field-overlay

				 (overlay-start field-overlay)

				 end)

		   (yas/synchronize-fields (overlay-get field-overlay 'yas/group)))

	       (let ((snippet (yas/snippet-of-current-keymap))

		     (done nil))

		 (if snippet

		     (do* ((groups (yas/snippet-groups snippet) (cdr groups))

			   (group (car groups) (car groups)))

			 ((or (null groups)

			      done))

		       (setq field-overlay (yas/field-overlay 

					    (yas/group-primary-field group)))

		       (when (and (= (overlay-start field-overlay)

				     (overlay-end field-overlay))

				  (= beg

				     (overlay-start field-overlay)))

			 (move-overlay field-overlay beg end)

			 (yas/synchronize-fields group)

			 (setq done t)))))))))))

(defun yas/undo-expand-snippet (start end key snippet)

  "Undo a snippet expansion. Delete the overlays. This undo can't be

redo-ed."

  (let ((undo (car buffer-undo-list)))

    (while (null undo)

      (setq buffer-undo-list (cdr buffer-undo-list))

      (setq undo (car buffer-undo-list)))

    ;; Remove this undo operation record

    (setq buffer-undo-list (cdr buffer-undo-list))

  (let ((inhibit-modification-hooks t)

	(buffer-undo-list t))

    (yas/exit-snippet snippet)

    (goto-char start)

    (delete-char (- end start))

    (insert key))))

(defun yas/expand-snippet (start end template)

  "Expand snippet at current point. Text between START and END

will be deleted before inserting template."

  (run-hooks 'yas/before-expand-snippet-hook)

  (goto-char start)

  (let ((key (buffer-substring-no-properties start end))

	(original-undo-list buffer-undo-list)

	(inhibit-modification-hooks t)

	(length (- end start))

	(column (current-column)))

    (save-restriction

      (narrow-to-region start start)

      (setq buffer-undo-list t)

      (insert template)

      ;; Step 1: do necessary indent

      (when yas/indent-line

	(let* ((indent (if indent-tabs-mode

			   (concat (make-string (/ column tab-width) ?\t)

				   (make-string (% column tab-width) ?\ ))

			 (make-string column ?\ ))))

	  (goto-char (point-min))

	  (while (and (zerop (forward-line))

		      (= (current-column) 0))

	    (insert indent))))

      ;; Step 2: protect backslash and backquote

      (yas/replace-all "\\\\" yas/escape-backslash)

      (yas/replace-all "\\`" yas/escape-backquote)

      ;; Step 3: evaluate all backquotes

      (goto-char (point-min))

      (while (re-search-forward "`\\([^`]*\\)`" nil t)

	(replace-match (yas/eval-string (match-string-no-properties 1))

		       t t))

      ;; Step 4: protect all escapes, including backslash and backquot

      ;; which may be produced in Step 3

      (yas/replace-all "\\\\" yas/escape-backslash)

      (yas/replace-all "\\`" yas/escape-backquote)

      (yas/replace-all "\\$" yas/escape-dollar)

      (let ((snippet (yas/make-snippet)))

	;; Step 5: Create fields

	(goto-char (point-min))

	(while (re-search-forward yas/field-regexp nil t)

	  (let ((number (or (match-string-no-properties 1)

			    (match-string-no-properties 2)))

		(transform nil)

		(value (match-string-no-properties 3)))

	    (when (eq (elt value 0) ?\$)

	      (setq transform (substring value 1))

	      (setq value nil))

	    (if (and number

		     (string= "0" number))

		(progn

		  (replace-match "")

		  (setf (yas/snippet-exit-marker snippet)

			(copy-marker (point) t)))

	      (yas/snippet-add-field

	       snippet

	       (yas/make-field

		(make-overlay (match-beginning 0) (match-end 0))

		(and number (string-to-number number))

		value

		transform)))))

	;; Step 6: Sort and link each field group

	(setf (yas/snippet-groups snippet)

	      (sort (yas/snippet-groups snippet)

		    '(lambda (group1 group2)

		       (yas/snippet-field-compare

			(yas/group-primary-field group1)

			(yas/group-primary-field group2)))))

	(let ((prev nil))

	  (dolist (group (yas/snippet-groups snippet))

	    (setf (yas/group-prev group) prev)

	    (when prev

	      (setf (yas/group-next prev) group))

	    (setq prev group)))

	;; Step 7: Create keymap overlay for snippet

	(let ((overlay (make-overlay (point-min)

				     (point-max)

				     nil

				     nil

				     t)))

	  (overlay-put overlay 

		       'modification-hooks

		       yas/keymap-overlay-modification-hooks)

	  (overlay-put overlay 

		       'insert-behind-hooks

		       yas/keymap-overlay-modification-hooks)

	  (overlay-put overlay 'keymap yas/keymap)

	  (overlay-put overlay 'yas/snippet-reference snippet)

	  (setf (yas/snippet-overlay snippet) overlay))

	;; Step 8: Replace fields with default values

	(dolist (group (yas/snippet-groups snippet))

	  (let ((value (yas/group-value group)))

	    (dolist (field (yas/group-fields group))

	      (let* ((overlay (yas/field-overlay field))

		     (start (overlay-start overlay))

		     (end (overlay-end overlay))

		     (length (- end start)))

		(goto-char start)

		(insert (yas/calculate-field-value field value))

		(delete-char length)))))

	;; Step 9: restore all escape characters

	(yas/replace-all yas/escape-dollar "$")

	(yas/replace-all yas/escape-backquote "`")

	(yas/replace-all yas/escape-backslash "\\")

	;; Step 10: Set up properties of overlays

	(dolist (group (yas/snippet-groups snippet))

	  (let ((overlay (yas/field-overlay

			  (yas/group-primary-field group))))

	    (overlay-put overlay 'yas/snippet snippet)

	    (overlay-put overlay 'yas/group group)

	    (overlay-put overlay 'yas/modified? nil)

	    (overlay-put overlay 'modification-hooks yas/overlay-modification-hooks)

	    (overlay-put overlay 'insert-in-front-hooks yas/overlay-insert-in-front-hooks)

	    (overlay-put overlay 'face 'yas/field-highlight-face)

	    (dolist (field (yas/group-fields group))

	      (unless (equal overlay (yas/field-overlay field))

		(overlay-put (yas/field-overlay field)

			     'face 

			     'yas/mirror-highlight-face)))))

	;; Step 11: move to end and make sure exit-marker exist

	(goto-char (point-max))

	(unless (yas/snippet-exit-marker snippet)

	  (setf (yas/snippet-exit-marker snippet) (copy-marker (point) t)))

	;; Step 12: Construct undo information

	(unless (eq original-undo-list t)

	  (add-to-list 'original-undo-list

		       `(apply yas/undo-expand-snippet

			       ,(point-min)

			       ,(point-max)

			       ,key

			       ,snippet)))

	;; Step 13: remove the trigger key

	(widen)

	(delete-char length)

	(setq buffer-undo-list original-undo-list)

	;; Step 14: place the cursor at a proper place

	(let ((groups (yas/snippet-groups snippet))

	      (exit-marker (yas/snippet-exit-marker snippet)))

	  (if groups

	      (goto-char (overlay-start 

			  (yas/field-overlay

			   (yas/group-primary-field

			    (car groups)))))

	    ;; no need to call exit-snippet, since no overlay created.

	    (yas/exit-snippet snippet)))))))

(defun yas/current-snippet-overlay (&optional point)

  "Get the most proper overlay which is belongs to a snippet."

  (let ((point (or point (point)))

	(snippet-overlay nil))

    (dolist (overlay (overlays-at point))

      (when (overlay-get overlay 'yas/snippet)

	(if (null snippet-overlay)

	    (setq snippet-overlay overlay)

	  (when (> (yas/snippet-id (overlay-get overlay 'yas/snippet))

		   (yas/snippet-id (overlay-get snippet-overlay 'yas/snippet)))

	    (setq snippet-overlay overlay)))))

    snippet-overlay))

(defun yas/snippet-of-current-keymap (&optional point)

  "Get the snippet holding the snippet keymap under POINT."

  (let ((point (or point (point)))

	(keymap-snippet nil)

	(snippet nil))

    (dolist (overlay (overlays-at point))

      (setq snippet (overlay-get overlay 'yas/snippet-reference))

      (when snippet

	(if (null keymap-snippet)

	    (setq keymap-snippet snippet)

	  (when (> (yas/snippet-id snippet)

		   (yas/snippet-id keymap-snippet))

	    (setq keymap-snippet snippet)))))

    keymap-snippet))

(defun yas/current-overlay-for-navigation ()

  "Get current overlay for navigation. Might be overlay at current or previous point."

  (let ((overlay1 (yas/current-snippet-overlay))

	(overlay2 (if (bobp)

		      nil

		    (yas/current-snippet-overlay (- (point) 1)))))

    (if (null overlay1)

	overlay2

      (if (or (null overlay2)

	      (eq (overlay-get overlay1 'yas/snippet) 

		  (overlay-get overlay2 'yas/snippet)))

	  overlay1

	(if (> (yas/snippet-id (overlay-get overlay2 'yas/snippet))

	       (yas/snippet-id (overlay-get overlay1 'yas/snippet)))

	    overlay2

	  overlay1)))))

(defun yas/navigate-group (group next?)

  "Go to next of previous field group. Exit snippet if none."

  (let ((target (if next?

		    (yas/group-next group)

		  (yas/group-prev group))))

    (if target

	(goto-char (overlay-start

		    (yas/field-overlay

		     (yas/group-primary-field target))))

      (yas/exit-snippet (yas/group-snippet group)))))

(defun yas/parse-template ()

  "Parse the template in the current buffer.

If the buffer contains a line of \"# --\" then the contents

above this line are ignored. Variables can be set above this

line through the syntax:

#name : value

Here's a list of currently recognized variables:

 * name

 * contributor

 * condition

#name: #include \"...\"

# --

#include \"$1\""

  (goto-char (point-min))

  (let (template name bound condition)

    (if (re-search-forward "^# --\n" nil t)

	(progn (setq template 

		     (buffer-substring-no-properties (point) 

						     (point-max)))

	       (setq bound (point))

	       (goto-char (point-min))

	       (while (re-search-forward "^#\\([^ ]+\\) *: *\\(.*\\)$" bound t)

		 (when (string= "name" (match-string-no-properties 1))

		   (setq name (match-string-no-properties 2)))

		 (when (string= "condition" (match-string-no-properties 1))

		   (setq condition (read (match-string-no-properties 2))))))

      (setq template

	    (buffer-substring-no-properties (point-min) (point-max))))

    (list template name condition)))

(defun yas/directory-files (directory file?)

  "Return directory files or subdirectories in full path."

  (remove-if (lambda (file)

	       (or (string-match "^\\."

				 (file-name-nondirectory file))

		   (if file?

		       (file-directory-p file)

		     (not (file-directory-p file)))))

	     (directory-files directory t)))

(defun yas/make-menu-binding (template)

  (lexical-let ((template template))

    (lambda ()

      (interactive)

      (yas/expand-snippet (point) 

			  (point)

			  template))))

(defun yas/modify-alist (alist key value)

  "Modify ALIST to map KEY to VALUE. return the new alist."

  (let ((pair (assoc key alist)))

    (if (null pair)

	(cons (cons key value)

	      alist)

      (setcdr pair value)

      alist)))

(defun yas/fake-keymap-for-popup (templates)

  "Create a fake keymap for popup menu usage."

  (cons 'keymap 

	(mapcar (lambda (pair)

		  (let* ((template (cdr pair))

			 (name (yas/template-name template))

			 (content (yas/template-content template)))

		    (list content 'menu-item name t)))

		templates)))

(defun yas/point-to-coord (&optional point)

  "Get the xoffset/yoffset information of POINT.

If POINT is not given, default is to current point.

If `posn-at-point' is not available (like in Emacs 21.3),

t is returned simply."

  (if (fboundp 'posn-at-point)

      (let ((x-y (posn-x-y (posn-at-point (or point (point))))))

	(list (list (+ (car x-y) 10)

		    (+ (cdr x-y) 20))

	      (selected-window)))

    t))

(defun yas/x-popup-menu-for-template (templates)

  "Show a popup menu listing templates to let the user select one."

  (car (x-popup-menu (yas/point-to-coord)

		     (yas/fake-keymap-for-popup templates))))

(defun yas/text-popup-for-template (templates)

  "Can't display popup menu in text mode. Just select the first one."

  (yas/template-content (cdar templates)))

(defun yas/dropdown-list-popup-for-template (templates)

  "Use dropdown-list.el to popup for templates. Better than the 

default \"select first\" behavior of `yas/text-popup-for-template'.

You can also use this in window-system.

NOTE: You need to download and install dropdown-list.el to use this."

  (if (fboundp 'dropdown-list)

      (let ((n (dropdown-list (mapcar (lambda (i)

					(yas/template-name

					 (cdr i)))

				      templates))))

	(if n

	    (yas/template-content

	     (cdr (nth n templates)))

	  nil))

    (error "Please download and install dropdown-list.el to use this")))

(defun yas/popup-for-template (templates)

  (if window-system

      (funcall yas/window-system-popup-function templates)

    (funcall yas/text-popup-function templates)))

(defun yas/load-directory-1 (directory &optional parent)

  "Really do the job of loading snippets from a directory 

hierarchy."

  (let ((mode-sym (intern (file-name-nondirectory directory)))

	(snippets nil))

    (with-temp-buffer

      (dolist (file (yas/directory-files directory t))

	(when (file-readable-p file)

	  (insert-file-contents file nil nil nil t)

	  (push (cons (file-name-nondirectory file)

		      (yas/parse-template))

		snippets))))

    (yas/define-snippets mode-sym

			 snippets

			 parent)

    (dolist (subdir (yas/directory-files directory nil))

      (yas/load-directory-1 subdir mode-sym))))

(defun yas/quote-string (string)

  "Escape and quote STRING.

foo\"bar\\! -> \"foo\\\"bar\\\\!\""

  (concat "\""

	  (replace-regexp-in-string "[\\\"]"

				    "\\\\\\&"

				    string

				    t)

	  "\""))

(defun yas/compile-bundle

  (&optional yasnippet yasnippet-bundle snippet-roots code)

  "Compile snippets in SNIPPET-ROOTS to a single bundle file.

SNIPPET-ROOTS is a list of root directories that contains the snippets

definition. YASNIPPET is the yasnippet.el file path. YASNIPPET-BUNDLE

is the output file of the compile result. CODE is the code you would

like to used to initialize yasnippet. Here's the default value for

all the parameters:

 (yas/compile-bundle \"yasnippet.el\"

                     \"./yasnippet-bundle.el\"

                     '(\"snippets\")

                     \"(yas/initialize)\")"

  (when (null yasnippet)

    (setq yasnippet "yasnippet.el"))

  (when (null yasnippet-bundle)

    (setq yasnippet-bundle "./yasnippet-bundle.el"))

  (when (null snippet-roots)

    (setq snippet-roots '("snippets")))

  (when (null code)

    (setq code "(yas/initialize)"))

  (let ((dirs (or (and (listp snippet-roots) snippet-roots)

		  (list snippet-roots)))

	(bundle-buffer nil))

    (with-temp-buffer

      (setq bundle-buffer (current-buffer))

      (insert-file-contents yasnippet)

      (goto-char (point-max))

      (insert ";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n")

      (insert ";;;;      Auto-generated code         ;;;;\n")

      (insert ";;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;\n")

      (insert code "\n")

      (flet ((yas/define-snippets 

	      (mode snippets &optional parent)

	      (with-current-buffer bundle-buffer

		(insert ";;; snippets for " (symbol-name mode) "\n")

		(insert "(yas/define-snippets '" (symbol-name mode) "\n")

		(insert "'(\n")

		(dolist (snippet snippets)

		  (insert "  (" 

			  (yas/quote-string (car snippet))

			  " "

			  (yas/quote-string (cadr snippet))

			  " "

			  (if (caddr snippet)

			      (yas/quote-string (caddr snippet))

			    "nil")

			  " "

			  (if (nth 3 snippet)