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      1 /*	$NetBSD: undo.c,v 1.8 2021/11/02 08:04:20 nia Exp $	*/
      2 
      3 /* undo.c: This file contains the undo routines for the ed line editor */
      4 /*-
      5  * Copyright (c) 1993 Andrew Moore, Talke Studio.
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     27  * SUCH DAMAGE.
     28  */
     29 
     30 #include <sys/cdefs.h>
     31 #ifndef lint
     32 #if 0
     33 static char *rcsid = "@(#)undo.c,v 1.1 1994/02/01 00:34:44 alm Exp";
     34 #else
     35 __RCSID("$NetBSD: undo.c,v 1.8 2021/11/02 08:04:20 nia Exp $");
     36 #endif
     37 #endif /* not lint */
     38 
     39 #include "ed.h"
     40 
     41 
     42 #define USIZE 100				/* undo stack size */
     43 undo_t *ustack = NULL;				/* undo stack */
     44 long usize = 0;					/* stack size variable */
     45 long u_p = 0;					/* undo stack pointer */
     46 
     47 /* push_undo_stack: return pointer to initialized undo node */
     48 undo_t *
     49 push_undo_stack(int type, long from, long to)
     50 {
     51 	int err;
     52 
     53 	if (u_p < usize ||
     54 	    (err = reallocarr(&ustack, usize += USIZE, sizeof(undo_t))) == 0) {
     55 		ustack[u_p].type = type;
     56 		ustack[u_p].t = get_addressed_line_node(to);
     57 		ustack[u_p].h = get_addressed_line_node(from);
     58 		return ustack + u_p++;
     59 	}
     60 	/* out of memory - release undo stack */
     61 	fprintf(stderr, "%s\n", strerror(err));
     62 	seterrmsg("out of memory");
     63 	clear_undo_stack();
     64 	free(ustack);
     65 	ustack = NULL;
     66 	usize = 0;
     67 	return NULL;
     68 }
     69 
     70 
     71 /* USWAP: swap undo nodes */
     72 #define USWAP(x,y) { \
     73 	undo_t utmp; \
     74 	utmp = x, x = y, y = utmp; \
     75 }
     76 
     77 
     78 long u_current_addr = -1;	/* if >= 0, undo enabled */
     79 long u_addr_last = -1;		/* if >= 0, undo enabled */
     80 
     81 /* pop_undo_stack: undo last change to the editor buffer */
     82 int
     83 pop_undo_stack(void)
     84 {
     85 	long n;
     86 	long o_current_addr = current_addr;
     87 	long o_addr_last = addr_last;
     88 
     89 	if (u_current_addr == -1 || u_addr_last == -1) {
     90 		seterrmsg("nothing to undo");
     91 		return ERR;
     92 	} else if (u_p)
     93 		modified = 1;
     94 	get_addressed_line_node(0);	/* this get_addressed_line_node last! */
     95 	SPL1();
     96 	for (n = u_p; n-- > 0;) {
     97 		switch(ustack[n].type) {
     98 		case UADD:
     99 			REQUE(ustack[n].h->q_back, ustack[n].t->q_forw);
    100 			break;
    101 		case UDEL:
    102 			REQUE(ustack[n].h->q_back, ustack[n].h);
    103 			REQUE(ustack[n].t, ustack[n].t->q_forw);
    104 			break;
    105 		case UMOV:
    106 		case VMOV:
    107 			REQUE(ustack[n - 1].h, ustack[n].h->q_forw);
    108 			REQUE(ustack[n].t->q_back, ustack[n - 1].t);
    109 			REQUE(ustack[n].h, ustack[n].t);
    110 			n--;
    111 			break;
    112 		default:
    113 			/*NOTREACHED*/
    114 			;
    115 		}
    116 		ustack[n].type ^= 1;
    117 	}
    118 	/* reverse undo stack order */
    119 	for (n = u_p; n-- > (u_p + 1)/ 2;)
    120 		USWAP(ustack[n], ustack[u_p - 1 - n]);
    121 	if (isglobal)
    122 		clear_active_list();
    123 	current_addr = u_current_addr, u_current_addr = o_current_addr;
    124 	addr_last = u_addr_last, u_addr_last = o_addr_last;
    125 	SPL0();
    126 	return 0;
    127 }
    128 
    129 
    130 /* clear_undo_stack: clear the undo stack */
    131 void
    132 clear_undo_stack(void)
    133 {
    134 	line_t *lp, *ep, *tl;
    135 
    136 	while (u_p--)
    137 		if (ustack[u_p].type == UDEL) {
    138 			ep = ustack[u_p].t->q_forw;
    139 			for (lp = ustack[u_p].h; lp != ep; lp = tl) {
    140 				unmark_line_node(lp);
    141 				tl = lp->q_forw;
    142 				free(lp);
    143 			}
    144 		}
    145 	u_p = 0;
    146 	u_current_addr = current_addr;
    147 	u_addr_last = addr_last;
    148 }
    149