bin/ed/undo.c

   1 /* undo.c: This file contains the undo routines for the ed line editor */
   2 /*-
   3  * Copyright (c) 1993 Andrew Moore, Talke Studio.
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  *
  27  * @(#)undo.c,v 1.1 1994/02/01 00:34:44 alm Exp
  28  * $FreeBSD: src/bin/ed/undo.c,v 1.12 2002/06/30 05:13:53 obrien Exp $
  29  * $DragonFly: src/bin/ed/undo.c,v 1.4 2007/04/06 23:36:54 pavalos Exp $
  30  */
  31
  32 #include "ed.h"
  33
  34
  35 #define USIZE 100                               /* undo stack size */
  36 undo_t *ustack = NULL;                          /* undo stack */
  37 long usize = 0;                                 /* stack size variable */
  38 long u_p = 0;                                   /* undo stack pointer */
  39
  40 /* push_undo_stack: return pointer to initialized undo node */
  41 undo_t *
  42 push_undo_stack(int type, long from, long to)
  43 {
  44         undo_t *t;
  45
  46 #if defined(sun) || defined(NO_REALLOC_NULL)
  47         if (ustack == NULL &&
  48             (ustack = (undo_t *) malloc((usize = USIZE) * sizeof(undo_t))) == NULL) {
  49                 fprintf(stderr, "%s\n", strerror(errno));
  50                 errmsg = "out of memory";
  51                 return NULL;
  52         }
  53 #endif
  54         t = ustack;
  55         if (u_p < usize ||
  56             (t = (undo_t *) realloc(ustack, (usize += USIZE) * sizeof(undo_t))) != NULL) {
  57                 ustack = t;
  58                 ustack[u_p].type = type;
  59                 ustack[u_p].t = get_addressed_line_node(to);
  60                 ustack[u_p].h = get_addressed_line_node(from);
  61                 return ustack + u_p++;
  62         }
  63         /* out of memory - release undo stack */
  64         fprintf(stderr, "%s\n", strerror(errno));
  65         errmsg = "out of memory";
  66         clear_undo_stack();
  67         free(ustack);
  68         ustack = NULL;
  69         usize = 0;
  70         return NULL;
  71 }
  72
  73
  74 /* USWAP: swap undo nodes */
  75 #define USWAP(x,y) { \
  76         undo_t utmp; \
  77         utmp = x, x = y, y = utmp; \
  78 }
  79
  80
  81 long u_current_addr = -1;       /* if >= 0, undo enabled */
  82 long u_addr_last = -1;          /* if >= 0, undo enabled */
  83
  84 /* pop_undo_stack: undo last change to the editor buffer */
  85 int
  86 pop_undo_stack(void)
  87 {
  88         long n;
  89         long o_current_addr = current_addr;
  90         long o_addr_last = addr_last;
  91
  92         if (u_current_addr == -1 || u_addr_last == -1) {
  93                 errmsg = "nothing to undo";
  94                 return ERR;
  95         } else if (u_p)
  96                 modified = 1;
  97         get_addressed_line_node(0);     /* this get_addressed_line_node last! */
  98         SPL1();
  99         for (n = u_p; n-- > 0;) {
 100                 switch(ustack[n].type) {
 101                 case UADD:
 102                         REQUE(ustack[n].h->q_back, ustack[n].t->q_forw);
 103                         break;
 104                 case UDEL:
 105                         REQUE(ustack[n].h->q_back, ustack[n].h);
 106                         REQUE(ustack[n].t, ustack[n].t->q_forw);
 107                         break;
 108                 case UMOV:
 109                 case VMOV:
 110                         REQUE(ustack[n - 1].h, ustack[n].h->q_forw);
 111                         REQUE(ustack[n].t->q_back, ustack[n - 1].t);
 112                         REQUE(ustack[n].h, ustack[n].t);
 113                         n--;
 114                         break;
 115                 default:
 116                         /*NOTREACHED*/
 117                         ;
 118                 }
 119                 ustack[n].type ^= 1;
 120         }
 121         /* reverse undo stack order */
 122         for (n = u_p; n-- > (u_p + 1)/ 2;)
 123                 USWAP(ustack[n], ustack[u_p - 1 - n]);
 124         if (isglobal)
 125                 clear_active_list();
 126         current_addr = u_current_addr, u_current_addr = o_current_addr;
 127         addr_last = u_addr_last, u_addr_last = o_addr_last;
 128         SPL0();
 129         return 0;
 130 }
 131
 132
 133 /* clear_undo_stack: clear the undo stack */
 134 void
 135 clear_undo_stack(void)
 136 {
 137         line_t *lp, *ep, *tl;
 138
 139         while (u_p--)
 140                 if (ustack[u_p].type == UDEL) {
 141                         ep = ustack[u_p].t->q_forw;
 142                         for (lp = ustack[u_p].h; lp != ep; lp = tl) {
 143                                 unmark_line_node(lp);
 144                                 tl = lp->q_forw;
 145                                 free(lp);
 146                         }
 147                 }
 148         u_p = 0;
 149         u_current_addr = current_addr;
 150         u_addr_last = addr_last;
 151 }