;;; viper-util.el --- Utilities used by viper.el

;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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, 675 Mass Ave, Cambridge, MA 02139, USA.

(require 'ring)

(defconst vip-xemacs-p (string-match "\\(Lucid\\|Xemacs\\)" emacs-version)
  "Whether it is XEmacs or not.")
(defconst vip-emacs-p (not vip-xemacs-p)
  "Whether it is Emacs or not.")


;;; Macros

(defmacro vip-deflocalvar (var default-value &optional documentation)
  (` (progn
       (defvar (, var) (, default-value)
	       (, (format "%s\n\(buffer local\)" documentation)))
       (make-variable-buffer-local '(, var))
     )))

(defmacro vip-loop (count body)
  "(vip-loop COUNT BODY) Execute BODY COUNT times."
  (list 'let (list (list 'count count))
	(list 'while '(> count 0)
	      body
	      '(setq count (1- count))
	      )))

(defmacro vip-buffer-live-p (buf)
  (` (and (, buf) (get-buffer (, buf)) (buffer-name (get-buffer (, buf))))))
  
;; return buffer-specific macro definition, given a full macro definition
(defmacro vip-kbd-buf-alist (macro-elt)
  (` (nth 1 (, macro-elt))))
;; get a pair: (curr-buffer . macro-definition)
(defmacro vip-kbd-buf-pair (macro-elt)
  (` (assoc (buffer-name) (vip-kbd-buf-alist (, macro-elt)))))
;; get macro definition for current buffer
(defmacro vip-kbd-buf-definition (macro-elt)
  (` (cdr (vip-kbd-buf-pair (, macro-elt)))))
  
;; return mode-specific macro definitions, given a full macro definition
(defmacro vip-kbd-mode-alist (macro-elt)
  (` (nth 2 (, macro-elt))))
;; get a pair: (major-mode . macro-definition)
(defmacro vip-kbd-mode-pair (macro-elt)
  (` (assoc major-mode (vip-kbd-mode-alist (, macro-elt)))))
;; get macro definition for the current major mode
(defmacro vip-kbd-mode-definition (macro-elt)
  (` (cdr (vip-kbd-mode-pair (, macro-elt)))))
  
;; return global macro definition, given a full macro definition
(defmacro vip-kbd-global-pair (macro-elt)
  (` (nth 3 (, macro-elt))))
;; get global macro definition from an elt of macro-alist
(defmacro vip-kbd-global-definition (macro-elt)
  (` (cdr (vip-kbd-global-pair (, macro-elt)))))
  
;; last elt of a sequence
(defsubst vip-seq-last-elt (seq)
  (elt seq (1- (length seq))))
  
;; Check if arg is a valid character for register
;; TYPE is a list that can contain `letter', `Letter', and `digit'.
;; Letter means lowercase letters, Letter means uppercase letters, and
;; digit means digits from 1 to 9.
;; If TYPE is nil, then down/uppercase letters and digits are allowed.
(defun vip-valid-register (reg &optional type)
  (or type (setq type '(letter Letter digit)))
  (or (if (memq 'letter type)
	  (and (<= ?a reg) (<= reg ?z)))
      (if (memq 'digit type)
	  (and (<= ?1 reg) (<= reg ?9)))
      (if (memq 'Letter type)
	  (and (<= ?A reg) (<= reg ?Z)))
      ))
      
(defun vip-valid-marker (marker)
  (if (markerp marker)
      (let ((buf (marker-buffer marker))
	    (pos (marker-position marker)))
	(save-excursion
	  (set-buffer buf)
	  (and (<= pos (point-max)) (<= (point-min) pos))))))
  

(defvar vip-minibuffer-overlay-priority 300)
(defvar vip-replace-overlay-priority 400)
(defvar vip-search-overlay-priority 500)
  

;;; XEmacs support

(if vip-xemacs-p
    (progn
      (fset 'vip-read-event (symbol-function 'next-command-event))
      (fset 'vip-make-overlay (symbol-function 'make-extent))
      (fset 'vip-overlay-start (symbol-function 'extent-start-position))
      (fset 'vip-overlay-end (symbol-function 'extent-end-position))
      (fset 'vip-overlay-put (symbol-function 'set-extent-property))
      (fset 'vip-overlay-p (symbol-function 'extentp))
      (fset 'vip-overlay-get (symbol-function 'extent-property))
      (fset 'vip-move-overlay (symbol-function 'set-extent-endpoints))
      (if window-system
	  (fset 'vip-iconify (symbol-function 'iconify-screen)))
      (fset 'vip-raise-frame (symbol-function 'raise-screen))
      (fset 'vip-window-frame (symbol-function 'window-screen))
      (fset 'vip-select-frame (symbol-function 'select-screen))
      (fset 'vip-selected-frame (symbol-function 'selected-screen))
      (fset 'vip-frame-selected-window
	    (symbol-function 'screen-selected-window))
      (fset 'vip-frame-parameters (symbol-function 'screen-parameters))
      (fset 'vip-modify-frame-parameters
            (symbol-function 'modify-screen-parameters))
      (cond (window-system
	     (fset 'vip-get-face (symbol-function 'get-face))
	     (fset 'vip-color-defined-p
		   (symbol-function 'x-valid-color-name-p))
	     (fset 'vip-display-color-p
		   (symbol-function 'x-color-display-p)))))
  (fset 'vip-read-event (symbol-function 'read-event))
  (fset 'vip-make-overlay (symbol-function 'make-overlay))
  (fset 'vip-overlay-start (symbol-function 'overlay-start))
  (fset 'vip-overlay-end (symbol-function 'overlay-end))
  (fset 'vip-overlay-put (symbol-function 'overlay-put))
  (fset 'vip-overlay-p (symbol-function 'overlayp))
  (fset 'vip-overlay-get (symbol-function 'overlay-get))
  (fset 'vip-move-overlay (symbol-function 'move-overlay))
  (if window-system
      (fset 'vip-iconify (symbol-function 'iconify-or-deiconify-frame)))
  (fset 'vip-raise-frame (symbol-function 'raise-frame))
  (fset 'vip-window-frame (symbol-function 'window-frame))
  (fset 'vip-select-frame (symbol-function 'select-frame))
  (fset 'vip-selected-frame (symbol-function 'selected-frame))
  (fset 'vip-frame-selected-window (symbol-function 'frame-selected-window))
  (fset 'vip-frame-parameters (symbol-function 'frame-parameters))
  (fset 'vip-modify-frame-parameters
	(symbol-function 'modify-frame-parameters))
  (cond (window-system
	 (fset 'vip-get-face (symbol-function 'internal-get-face))
	 (fset 'vip-color-defined-p (symbol-function 'x-color-defined-p))
	 (fset 'vip-display-color-p (symbol-function 'x-display-color-p)))))
  
;; OS/2
(cond ((eq window-system 'pm)
       (fset 'vip-color-defined-p
	     (function (lambda (color) (assoc color pm-color-alist))))))
    
;; needed to smooth out the difference between Emacs and XEmacs
(defsubst vip-italicize-face (face)
  (if vip-xemacs-p
      (make-face-italic face)
    (make-face-italic face nil 'noerror)))
    
;; test if display is color and the colors are defined
(defsubst vip-can-use-colors (&rest colors)
  (if (vip-display-color-p)
      (not (memq nil (mapcar 'vip-color-defined-p colors)))
    ))

;; currently doesn't work for XEmacs
(defun vip-change-cursor-color (new-color)
  (if (and window-system  (vip-display-color-p)
	   (stringp new-color) (vip-color-defined-p new-color))
      (vip-modify-frame-parameters
       (vip-selected-frame) (list (cons 'cursor-color new-color)))))
	 
(defsubst vip-save-cursor-color ()
  (if (and window-system (vip-display-color-p))
      (let ((color (cdr (assoc 'cursor-color (vip-frame-parameters)))))
	(if (and (stringp color) (vip-color-defined-p color)
		 (not (string= color vip-replace-overlay-cursor-color)))
	    (vip-overlay-put vip-replace-overlay 'vip-cursor-color color)))))
	
(defsubst vip-restore-cursor-color ()
  (vip-change-cursor-color
   (vip-overlay-get vip-replace-overlay 'vip-cursor-color)))
	 

;; Check the current version against the major and minor version numbers
;; using op: cur-vers op major.minor If emacs-major-version or
;; emacs-minor-version are not defined, we assume that the current version
;; is hopelessly outdated.  We assume that emacs-major-version and
;; emacs-minor-version are defined.  Otherwise, for Emacs/XEmacs 19, if the
;; current minor version is < 10 (xemacs) or < 23 (emacs) the return value
;; will be nil (when op is =, >, or >=) and t (when op is <, <=), which may be
;; incorrect. However, this gives correct result in our cases, since we are
;; testing for sufficiently high Emacs versions.
(defun vip-check-version (op major minor &optional type-of-emacs)
  (if (and (boundp 'emacs-major-version) (boundp 'emacs-minor-version))
      (and (cond ((eq type-of-emacs 'xemacs) vip-xemacs-p)
		 ((eq type-of-emacs 'emacs) vip-emacs-p)
		 (t t))
	   (cond ((eq op '=) (and (= emacs-minor-version minor)
				  (= emacs-major-version major)))
		 ((memq op '(> >= < <=))
		  (and (or (funcall op emacs-major-version major)
			   (= emacs-major-version major))
		       (if (= emacs-major-version major)
			   (funcall op emacs-minor-version minor)
			 t)))
		 (t
		  (error "%S: Invalid op in vip-check-version" op))))
    (cond ((memq op '(= > >=)) nil)
	  ((memq op '(< <=)) t))))
  
    
;; Early versions of XEmacs didn't have window-live-p (or it didn't work right)
(if (vip-check-version '< 19 11 'xemacs)
    (defun window-live-p (win)
      (let ((visible nil))
	(walk-windows
	 '(lambda (walk-win)
	    (if(equal walk-win win)
		(setq visible t)))
	 nil 'all-screens)
	visible))
  )


(defun vip-get-visible-buffer-window (wind)
  (if vip-xemacs-p
      (get-buffer-window wind t)
    (get-buffer-window wind 'visible)))
    
    
(defun vip-line-pos (pos)
  "Return line position.
If pos is 'start then returns position of line start.
If pos is 'end, returns line end. If pos is 'mid, returns line center.
Pos = 'indent returns beginning of indentation.
Otherwise, returns point. Current point is not moved in any case."
  (let ((cur-pos (point))
        (result))
    (cond
     ((equal pos 'start)
      (beginning-of-line))
     ((equal pos 'end)
      (end-of-line))
     ((equal pos 'mid)
      (goto-char (+ (vip-line-pos 'start) (vip-line-pos 'end) 2)))
     ((equal pos 'indent)
      (back-to-indentation))
     (t   nil))
    (setq result (point))
    (goto-char cur-pos)
    result))


(defun vip-move-marker-locally (var pos &optional buffer)
  "Like move-marker but creates a virgin marker if arg isn't already a marker.
The first argument must eval to a variable name.
Arguments: (var-name position &optional buffer).

This is useful for moving markers that are supposed to be local.
For this, VAR-NAME should be made buffer-local with nil as a default.
Then, each time this var is used in `vip-move-marker-locally' in a new
buffer, a new marker will be created."
  (if (markerp (eval var))
      ()
    (set var (make-marker)))
  (move-marker (eval var) pos buffer))


(defun vip-message-conditions (conditions)
  "Print CONDITIONS as a message."
  (let ((case (car conditions)) (msg (cdr conditions)))
    (if (null msg)
	(message "%s" case)
      (message "%s: %s" case (mapconcat 'prin1-to-string msg " ")))
    (beep 1)))


;;; List/alist utilities
	
(defun vip-list-to-alist (lst)
  "Convert LIST to an alist."
  (let ((alist))
    (while lst
      (setq alist (cons (list (car lst)) alist))
      (setq lst (cdr lst)))
    alist))	

(defun vip-alist-to-list (alst)
  "Convert ALIST to a list."
  (let ((lst))
    (while alst
      (setq lst (cons (car (car alst)) lst))
      (setq alst (cdr alst)))
    lst))

(defun vip-filter-alist (regexp alst)
  "Filter ALIST using REGEXP. Return alist whose elements match the regexp."
  (interactive "s x")
  (let ((outalst) (inalst alst))
    (while (car inalst)
      (if (string-match regexp (car (car inalst)))
	  (setq outalst (cons (car inalst) outalst)))
      (setq inalst (cdr inalst)))
    outalst))    
       
(defun vip-filter-list (regexp lst)
  "Filter LIST using REGEXP. Return list whose elements match the regexp."
  (interactive "s x")
  (let ((outlst) (inlst lst))
    (while (car inlst)
      (if (string-match regexp (car inlst))
	  (setq outlst (cons (car inlst) outlst)))
      (setq inlst (cdr inlst)))
    outlst))    

   
;; Append LIS2 to LIS1, both alists, by side-effect and returns LIS1
;; LIS2 is modified by filtering it: deleting its members of the form
;; \(car elt\) such that (car elt') is in LIS1.
(defun vip-append-filter-alist (lis1 lis2)
  (let ((temp lis1)
	elt)
  
    ;;filter-append the second list
    (while temp
      ;; delete all occurrences
      (while (setq elt (assoc (car (car temp)) lis2))
	(setq lis2 (delq elt lis2)))
      (setq temp (cdr temp)))
    
    (nconc lis1 lis2)))
      



;;; Insertion ring

;; Rotate RING's index. DIRection can be positive or negative.
(defun vip-ring-rotate1 (ring dir)
  (if (and (ring-p ring) (> (ring-length ring) 0))
      (progn
	(setcar ring (cond ((> dir 0)
			    (ring-plus1 (car ring) (ring-length ring)))
			   ((< dir 0)
			    (ring-minus1 (car ring) (ring-length ring)))
			   ;; don't rotate if dir = 0
			   (t (car ring))))
	(vip-current-ring-item ring)
	)))
	
(defun vip-special-ring-rotate1 (ring dir)
  (if (memq vip-intermediate-command
	    '(repeating-display-destructive-command
	      repeating-insertion-from-ring))
      (vip-ring-rotate1 ring dir)
    ;; don't rotate otherwise
    (vip-ring-rotate1 ring 0)))
    
;; current ring item; if N is given, then so many items back from the
;; current
(defun vip-current-ring-item (ring &optional n)
  (setq n (or n 0))
  (if (and (ring-p ring) (> (ring-length ring) 0))
      (aref (cdr (cdr ring)) (mod (- (car ring) 1 n) (ring-length ring)))))
    
;; push item onto ring. the second argument is a ring-variable, not value.
(defun vip-push-onto-ring (item ring-var)
  (or (ring-p (eval ring-var))
      (set ring-var (make-ring (eval (intern (format "%S-size" ring-var))))))
  (or (null item) ; don't push nil
      (and (stringp item) (string= item "")) ; or empty strings
      (equal item (vip-current-ring-item (eval ring-var))) ; or old stuff
      ;; Since vip-set-destructive-command checks if we are inside vip-repeat,
      ;;    we don't check whether this-command-keys is a `.'.
      ;;    The cmd vip-repeat makes a call to the current function only if
      ;;    `.' is executing a command from the command history. It doesn't
      ;;    call the push-onto-ring function if `.' is simply repeating the
      ;;    last destructive command.
      ;; We only check for ESC (which happens when we do insert with a
      ;;    prefix argument, or if this-command-keys doesn't give anything
      ;;    meaningful (in that case we don't know what to show to the user).
      (and (eq ring-var 'vip-command-ring)
	   (string-match "\\([0-9]*\e\\|^[ \t]*$\\|escape\\)"
			 (vip-array-to-string (this-command-keys))))
      (vip-ring-insert (eval ring-var) item))
  )
  

;; removing elts from ring seems to break it
(defun vip-cleanup-ring (ring)
  (or (< (ring-length ring) 2)
      (null (vip-current-ring-item ring))
      ;; last and previous equal
      (if (equal (vip-current-ring-item ring) (vip-current-ring-item ring 1))
	  (vip-ring-pop ring))))
	  
;; ring-remove seems to be buggy, so we concocted this for our purposes.
(defun vip-ring-pop (ring)
  (let* ((ln (ring-length ring))
	 (vec (cdr (cdr ring)))
	 (veclen (length vec))
	 (hd (car ring))
	 (idx (max 0 (ring-minus1 hd ln)))
	 (top-elt (aref vec idx)))
	
	;; shift elements
	(while (< (1+ idx) veclen)
	  (aset vec idx (aref vec (1+ idx)))
	  (setq idx (1+ idx)))
	(aset vec idx nil)
	
	(setq hd (max 0 (ring-minus1 hd ln)))
	(if (= hd (1- ln)) (setq hd 0))
	(setcar ring hd) ; move head
	(setcar (cdr ring) (max 0 (1- ln))) ; adjust length
	top-elt
	))
	
(defun vip-ring-insert (ring item)
  (let* ((ln (ring-length ring))
	 (vec (cdr (cdr ring)))
	 (veclen (length vec))
	 (hd (car ring))
	 (vecpos-after-hd (if (= hd 0) ln hd))
	 (idx ln))
	 
    (if (= ln veclen)
	(progn
	  (aset vec hd item) ; hd is always 1+ the actual head index in vec
	  (setcar ring (ring-plus1 hd ln)))
      (setcar (cdr ring) (1+ ln))
      (setcar ring (ring-plus1 vecpos-after-hd (1+ ln)))
      (while (and (>= idx vecpos-after-hd) (> ln 0))
	(aset vec idx (aref vec (1- idx)))
	(setq idx (1- idx)))
      (aset vec vecpos-after-hd item))
    item))
	

;;; String utilities

;; If STRING is longer than MAX-LEN, truncate it and print ...... instead
;; PRE-STRING is a string to prepend to the abbrev string.
;; POST-STRING is a string to append to the abbrev string.
;; ABBREV_SIGN is a string to be inserted before POST-STRING
;; if the orig string was truncated. 
(defun vip-abbreviate-string (string max-len
				     pre-string post-string abbrev-sign)
  (let (truncated-str)
    (setq truncated-str
	  (if (stringp string) 
	      (substring string 0 (min max-len (length string)))))
    (cond ((null truncated-str) "")
	  ((> (length string) max-len)
	   (format "%s%s%s%s"
		   pre-string truncated-str abbrev-sign post-string))
	  (t (format "%s%s%s" pre-string truncated-str post-string)))))
	  

;;; Saving settings in custom file

(defun vip-save-setting (var message custom-file &optional erase-msg)
  "Save the current setting of VAR in CUSTOM-FILE.
If given, MESSAGE is a message to be displayed after that.
This message is erased after 2 secs, if erase-msg is non-nil.
Arguments: (vip-save-setting var message custom-file &optional erase-message)"
  (let* ((var-name (symbol-name var))
	 (var-val (if (boundp var) (eval var)))
	 (regexp (format "^[^;]*%s[ \t\n]*[a-zA-Z---_']*[ \t\n)]" var-name))
	 (buf (find-file-noselect (substitute-in-file-name custom-file)))
	)
    (message message)
    (save-excursion
      (set-buffer buf)
      (goto-char (point-min))
      (if (re-search-forward regexp nil t)
	  (let ((reg-end (1- (match-end 0))))
	    (search-backward var-name)
	    (delete-region (match-beginning 0) reg-end)
	    (goto-char (match-beginning 0))
	    (insert (format "%s  '%S" var-name var-val)))
	(goto-char (point-max))
	(if (not (bolp)) (insert "\n"))
	(insert (format "(setq %s '%S)\n" var-name var-val)))
      (save-buffer))
      (kill-buffer buf)
      (if erase-msg
	  (progn
	    (sit-for 2)
	    (message "")))
      ))
      
;; Save STRING in CUSTOM-FILE. If PATTERN is non-nil, remove strings that
;; match this pattern.
(defun vip-save-string-in-file (string custom-file &optional pattern)
  (let ((buf (find-file-noselect (substitute-in-file-name custom-file))))
    (save-excursion
      (set-buffer buf)
      (goto-char (point-min))
      (if pattern (delete-matching-lines pattern))
      (goto-char (point-max))
      (if string (insert string))
      (save-buffer))
    (kill-buffer buf)
    ))
    

;;; Overlays

;; Search

(defun vip-flash-search-pattern ()
  (if (vip-overlay-p vip-search-overlay)
      (vip-move-overlay vip-search-overlay (match-beginning 0) (match-end 0))
    (setq vip-search-overlay
	  (vip-make-overlay
	   (match-beginning 0) (match-end 0) (current-buffer))))
  
  (vip-overlay-put vip-search-overlay 'priority vip-search-overlay-priority)
  (if window-system
      (progn
	(vip-overlay-put vip-search-overlay 'face vip-search-face)
	(sit-for 2)
	(vip-overlay-put vip-search-overlay 'face nil))))

;; Replace state

(defun vip-set-replace-overlay (beg end)
  (if (vip-overlay-p vip-replace-overlay)
      (vip-move-replace-overlay beg end)
    (setq vip-replace-overlay (vip-make-overlay beg end (current-buffer)))
    (vip-overlay-put vip-replace-overlay
		     'vip-start 
		     (move-marker (make-marker)
				  (vip-overlay-start vip-replace-overlay)))
    (vip-overlay-put vip-replace-overlay
		     'vip-end 
		     (move-marker (make-marker)
				  (vip-overlay-end vip-replace-overlay)))
    (vip-overlay-put 
     vip-replace-overlay 'priority vip-replace-overlay-priority)) 
  (if window-system
      (vip-overlay-put vip-replace-overlay 'face vip-replace-overlay-face))
  (vip-save-cursor-color)
  (vip-change-cursor-color vip-replace-overlay-cursor-color)
  )
  
  
(defsubst vip-hide-replace-overlay ()
  (vip-restore-cursor-color)
  (if window-system
      (vip-overlay-put vip-replace-overlay 'face nil)))


    
(defsubst vip-replace-start ()
  (vip-overlay-get vip-replace-overlay 'vip-start))
(defsubst vip-replace-end ()
  (vip-overlay-get vip-replace-overlay 'vip-end))
  
(defsubst vip-move-replace-overlay (beg end)
  (vip-move-overlay vip-replace-overlay beg end)
  (move-marker (vip-replace-start) (vip-overlay-start vip-replace-overlay))
  (move-marker (vip-replace-end) (vip-overlay-end vip-replace-overlay)))
 

;; Minibuffer

(defun vip-set-minibuffer-overlay ()
  (vip-check-minibuffer-overlay)
  ;; We always move the minibuffer overlay, since in XEmacs
  ;; this overlay may get detached. Moving will reattach it.
  ;; This overlay is also moved via the post-command-hook,
  ;; to insure taht it covers the whole minibuffer.
  (vip-move-minibuffer-overlay)
  (if window-system
      (progn
	(vip-overlay-put
	 vip-minibuffer-overlay 'face vip-minibuffer-current-face)
	(vip-overlay-put 
	 vip-minibuffer-overlay 'priority vip-minibuffer-overlay-priority))
	 ))
       
(defun vip-check-minibuffer-overlay ()
  (if (vip-overlay-p vip-minibuffer-overlay)
      ()
    (setq vip-minibuffer-overlay
	  (vip-make-overlay 1 (1+ (buffer-size)) (current-buffer)))))

;; arguments to this function are dummies. they are needed just because
;; it is used as a insert-in-front-hook to vip-minibuffer-overlay, and such
;; hooks require 3 arguments.
(defun vip-move-minibuffer-overlay (&optional overl beg end)
  (if (vip-is-in-minibuffer)
      (progn
	(vip-check-minibuffer-overlay)
	(vip-move-overlay vip-minibuffer-overlay 1 (1+ (buffer-size))))))

(defsubst vip-is-in-minibuffer ()
  (string-match "\*Minibuf-" (buffer-name)))
  


;;; XEmacs compatibility
    
;; Sit for VAL miliseconds. XEmacs doesn't support the milisecond arg to
;; sit-for, so this is for compatibility.
(defsubst vip-sit-for-short (val &optional nodisp)
  (if vip-xemacs-p
      (sit-for (/ val 1000.0) nodisp)
    (sit-for 0 val nodisp)))

;; EVENT may be a single event of a sequence of events
(defsubst vip-ESC-event-p (event)
  (let ((ESC-keys '(?\e (control \[) escape))
	(key (vip-event-key event)))
    (member key ESC-keys)))
	
;; like (set-mark-command nil) but doesn't push twice, if (car mark-ring)
;; is the same as (mark t).
(defsubst vip-set-mark-if-necessary ()
  (setq mark-ring (delete (vip-mark-marker) mark-ring))
  (set-mark-command nil))
  
(defsubst vip-mark-marker ()
  (if vip-xemacs-p
      (mark-marker t)
    (mark-marker)))
       
;; In transient mark mode (zmacs mode), it is annoying when regions become
;; highlighted due to Viper's pushing marks. So, we deactivate marks, unless
;; the user explicitly wants highlighting, e.g., by hitting '' or ``
(defun vip-deactivate-mark ()
  (if vip-xemacs-p
      (zmacs-deactivate-region)
    (deactivate-mark)))

    
(defsubst vip-events-to-keys (events)
  (cond (vip-xemacs-p (events-to-keys events))
	(t events)))
		  
	
(defun vip-eval-after-load (file form)
  (if vip-emacs-p
      (eval-after-load file form)
    (or (assoc file after-load-alist)
	(setq after-load-alist (cons (list file) after-load-alist)))
    (let ((elt (assoc file after-load-alist)))
      (or (member form (cdr elt))
	  (setq elt (nconc elt (list form)))))
    form
    ))
    
    
;; like read-event, but in XEmacs also try to convert to char, if possible
(defun vip-read-event-convert-to-char ()
  (let (event)
    (if vip-emacs-p
	(read-event)
      (setq event (next-command-event))
      (or (event-to-character event)
	  event))
    ))


;; Enacs has a bug in eventp, which causes (eventp nil) to return (nil)
;; instead of nil, if '(nil) was previously inadvertantly assigned to
;; unread-command-events
(defun vip-event-key (event)
  (or (and event (eventp event))
      (error "vip-event-key: Wrong type argument, eventp, %S" event))
  (let ((mod (event-modifiers event))
	basis)
    (setq basis
	  (cond
	   (vip-xemacs-p
	    (cond ((key-press-event-p event)
		   (event-key event))
		  ((button-event-p event)
		   (concat "mouse-" (event-button event)))
		  (t 
		   (error "vip-event-key: Unknown event, %S" event))))
	   (t 
	    ;; Emacs doesn't handle capital letters correctly, since
	    ;; \S-a isn't considered the same as A (it behaves as
	    ;; plain `a' instead). So we take care of this here
	    (if (and (numberp event) (<= ?A event) (<= event ?Z))
		(setq mod nil
		      event event)
	      (event-basic-type event)))))
    
    (if (numberp basis)
	(setq basis
	      (if (= basis ?\C-?)
		  (list 'control '\?) ; taking care of an emacs bug
		(intern (char-to-string basis)))))
    
    (if mod
	(append mod (list basis))
      basis)
    ))
    
(defun vip-key-to-emacs-key (key)
  (let (key-name char-p modifiers mod-char-list base-key base-key-name)
    (cond (vip-xemacs-p key)
	  ((symbolp key)
	   (setq key-name (symbol-name key))
	   (if (= (length key-name) 1) ; character event
	       (string-to-char key-name)
	     key))
	  ((listp key)
	   (setq modifiers (subseq key 0 (1- (length key)))
		 base-key (vip-seq-last-elt key)
		 base-key-name (symbol-name base-key)
		 char-p (= (length base-key-name) 1))
	   (setq mod-char-list
		 (mapcar
		  '(lambda (elt) (upcase (substring (symbol-name elt) 0 1)))
		  modifiers))
	   (if char-p
	       (setq key-name
		     (car (read-from-string
			   (concat
			    "?\\"
			    (mapconcat 'identity mod-char-list "-\\")
			    "-"
			    base-key-name))))
	     (setq key-name
		   (intern
		    (concat
		     (mapconcat 'identity mod-char-list "-")
		     "-"
		     base-key-name))))))
    ))


;; Args can be a sequence of events, a string, or a Viper macro.  Will try to
;; convert events to keys and, if all keys are regular printable
;; characters, will return a string. Otherwise, will return a string
;; representing a vector of converted events. If the input was a Viper macro,
;; will return a string that represents this macro as a vector.
(defun vip-array-to-string (event-seq &optional representation)
  (let (temp)
    (cond ((stringp event-seq) event-seq)
	  ((vip-event-vector-p event-seq)
	    (setq temp (mapcar 'vip-event-key event-seq))
	    (if (vip-char-symbol-sequence-p temp)
		(mapconcat 'symbol-name temp "")
	      (prin1-to-string (vconcat temp))))
	  ((vip-char-symbol-sequence-p event-seq)
	   (mapconcat 'symbol-name event-seq ""))
	  (t (prin1-to-string event-seq)))))
	   
    
(defsubst vip-fast-keysequence-p ()
  (not (vip-sit-for-short vip-fast-keyseq-timeout t)))
    
(defun vip-read-char-exclusive ()
  (let (char
	(echo-keystrokes 1))
    (while (null char)
      (condition-case nil
	  (setq char (read-char))
	(error
	 ;; skip event if not char
	 (vip-read-event))))
    char))

    
      
(defun vip-setup-master-buffer (&rest other-files-or-buffers)
  "Set up the current buffer as a master buffer.
Arguments become related buffers. This function should normally be used in
the `Local variables' section of a file."
  (setq vip-related-files-and-buffers-ring 
	(make-ring (1+ (length other-files-or-buffers))))
  (mapcar '(lambda (elt)
	     (vip-ring-insert vip-related-files-and-buffers-ring elt))
	  other-files-or-buffers)
  (vip-ring-insert vip-related-files-and-buffers-ring (buffer-name))
  )
  
  
(provide 'viper-util)

;;;  viper-util.el ends here