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;;; calc-undo.el --- undo functions for Calc -*- lexical-binding:t -*-
;; Copyright (C) 1990-1993, 2001-2025 Free Software Foundation, Inc.
;; Author: David Gillespie <daveg@synaptics.com>
;; 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 3 of the License, 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. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;;; Code:
;; This file is autoloaded from calc-ext.el.
(require 'calc-ext)
(require 'calc-macs)
;;; Undo.
;;;###autoload
(defun calc-undo (n)
(interactive "p")
(when calc-executing-macro
(error "Use C-x e, not X, to run a keyboard macro that uses Undo"))
(if (<= n 0)
(if (< n 0)
(calc-redo (- n))
(calc-last-args 1))
(calc-wrapper
(when (null (nthcdr (1- n) calc-undo-list))
(error "No further undo information available"))
(setq calc-undo-list
(prog1
(nthcdr n calc-undo-list)
(let ((saved-stack-top calc-stack-top))
(let ((calc-stack-top 0))
(calc-handle-undos calc-undo-list n))
(setq calc-stack-top saved-stack-top))))
(message "Undo!"))))
(defun calc-handle-undos (cl n)
(when (> n 0)
(let ((old-redo calc-redo-list))
(setq calc-undo-list nil)
(calc-handle-undo (car cl))
(setq calc-redo-list (append calc-undo-list old-redo)))
(calc-handle-undos (cdr cl) (1- n))))
(defun calc-handle-undo (list)
(when list
(let ((action (car list)))
(cond
((eq (car action) 'push)
(calc-pop-stack 1 (nth 1 action) t))
((eq (car action) 'pop)
(calc-push-list (nth 2 action) (nth 1 action)))
((eq (car action) 'set)
(calc-record-undo (list 'set (nth 1 action)
(symbol-value (nth 1 action))))
(set (nth 1 action) (nth 2 action)))
((eq (car action) 'store)
(let ((v (intern (nth 1 action))))
(calc-record-undo (list 'store (nth 1 action)
(and (boundp v) (symbol-value v))))
(if (y-or-n-p (format "Un-store variable %s? "
(calc-var-name (nth 1 action))))
(progn
(if (nth 2 action)
(set v (nth 2 action))
(makunbound v))
(calc-refresh-evaltos v)))))
((eq (car action) 'eval)
(calc-record-undo (append (list 'eval (nth 2 action) (nth 1 action))
(cdr (cdr (cdr action)))))
(apply (nth 1 action) (cdr (cdr (cdr action))))))
(calc-handle-undo (cdr list)))))
(defun calc-redo (n)
(interactive "p")
(when calc-executing-macro
(error "Use C-x e, not X, to run a keyboard macro that uses Redo"))
(if (<= n 0)
(calc-undo (- n))
(calc-wrapper
(when (null (nthcdr (1- n) calc-redo-list))
(error "Unable to redo"))
(setq calc-redo-list
(prog1
(nthcdr n calc-redo-list)
(let ((saved-stack-top calc-stack-top))
(let ((calc-stack-top 0))
(calc-handle-redos calc-redo-list n))
(setq calc-stack-top saved-stack-top))))
(message "Redo!"))))
(defun calc-handle-redos (cl n)
(when (> n 0)
(let ((old-undo calc-undo-list))
(setq calc-undo-list nil)
(calc-handle-undo (car cl))
(setq calc-undo-list (append calc-undo-list old-undo)))
(calc-handle-redos (cdr cl) (1- n))))
(defun calc-last-args (n)
(interactive "p")
(when calc-executing-macro
(error "Use C-x e, not X, to run a keyboard macro that uses last-args"))
(calc-wrapper
(let ((urec (calc-find-last-x calc-undo-list n)))
(if urec
(calc-handle-last-x urec)
(error "Not enough undo information available")))))
(defun calc-handle-last-x (list)
(when list
(let ((action (car list)))
(if (eq (car action) 'pop)
(calc-pop-push-record-list 0 "larg"
(delq 'top-of-stack (nth 2 action))))
(calc-handle-last-x (cdr list)))))
(defun calc-find-last-x (ul n)
(when ul
(if (calc-undo-does-pushes (car ul))
(if (<= n 1)
(car ul)
(calc-find-last-x (cdr ul) (1- n)))
(calc-find-last-x (cdr ul) n))))
(defun calc-undo-does-pushes (list)
(and list
(or (eq (car (car list)) 'pop)
(calc-undo-does-pushes (cdr list)))))
(provide 'calc-undo)
;;; calc-undo.el ends here
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