text_cmds/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
  28 #include <sys/cdefs.h>
  29 __FBSDID("$FreeBSD: src/bin/ed/undo.c,v 1.12 2002/06/30 05:13:53 obrien Exp $");
  30
  31 #include "ed.h"
  32
  33
  34 #define USIZE 100                               /* undo stack size */
  35 undo_t *ustack = NULL;                          /* undo stack */
  36 long usize = 0;                                 /* stack size variable */
  37 long u_p = 0;                                   /* undo stack pointer */
  38
  39 /* push_undo_stack: return pointer to initialized undo node */
  40 undo_t *
  41 push_undo_stack(int type, long from, long to)
  42 {
  43         undo_t *t;
  44
  45 #if defined(sun) || defined(NO_REALLOC_NULL)
  46         if (ustack == NULL &&
  47             (ustack = (undo_t *) malloc((usize = USIZE) * sizeof(undo_t))) == NULL) {
  48                 fprintf(stderr, "%s\n", strerror(errno));
  49                 errmsg = "out of memory";
  50                 return NULL;
  51         }
  52 #endif
  53         t = ustack;
  54         if (u_p < usize ||
  55             (t = (undo_t *) realloc(ustack, (usize += USIZE) * sizeof(undo_t))) != NULL) {
  56                 ustack = t;
  57                 ustack[u_p].type = type;
  58                 ustack[u_p].t = get_addressed_line_node(to);
  59                 ustack[u_p].h = get_addressed_line_node(from);
  60                 return ustack + u_p++;
  61         }
  62         /* out of memory - release undo stack */
  63         fprintf(stderr, "%s\n", strerror(errno));
  64         errmsg = "out of memory";
  65         clear_undo_stack();
  66         free(ustack);
  67         ustack = NULL;
  68         usize = 0;
  69         return NULL;
  70 }
  71
  72
  73 /* USWAP: swap undo nodes */
  74 #define USWAP(x,y) { \
  75         undo_t utmp; \
  76         utmp = x, x = y, y = utmp; \
  77 }
  78
  79
  80 long u_current_addr = -1;       /* if >= 0, undo enabled */
  81 long u_addr_last = -1;          /* if >= 0, undo enabled */
  82
  83 /* pop_undo_stack: undo last change to the editor buffer */
  84 int
  85 pop_undo_stack(void)
  86 {
  87         long n;
  88         long o_current_addr = current_addr;
  89         long o_addr_last = addr_last;
  90
  91         if (u_current_addr == -1 || u_addr_last == -1) {
  92                 errmsg = "nothing to undo";
  93                 return ERR;
  94         } else if (u_p)
  95                 modified = 1;
  96         get_addressed_line_node(0);     /* this get_addressed_line_node last! */
  97         SPL1();
  98         for (n = u_p; n-- > 0;) {
  99                 switch(ustack[n].type) {
 100                 case UADD:
 101                         REQUE(ustack[n].h->q_back, ustack[n].t->q_forw);
 102                         break;
 103                 case UDEL:
 104                         REQUE(ustack[n].h->q_back, ustack[n].h);
 105                         REQUE(ustack[n].t, ustack[n].t->q_forw);
 106                         break;
 107                 case UMOV:
 108                 case VMOV:
 109                         REQUE(ustack[n - 1].h, ustack[n].h->q_forw);
 110                         REQUE(ustack[n].t->q_back, ustack[n - 1].t);
 111                         REQUE(ustack[n].h, ustack[n].t);
 112                         n--;
 113                         break;
 114                 default:
 115                         /*NOTREACHED*/
 116                         ;
 117                 }
 118                 ustack[n].type ^= 1;
 119         }
 120         /* reverse undo stack order */
 121         for (n = u_p; n-- > (u_p + 1)/ 2;)
 122                 USWAP(ustack[n], ustack[u_p - 1 - n]);
 123         if (isglobal)
 124                 clear_active_list();
 125         current_addr = u_current_addr, u_current_addr = o_current_addr;
 126         addr_last = u_addr_last, u_addr_last = o_addr_last;
 127         SPL0();
 128         return 0;
 129 }
 130
 131
 132 /* clear_undo_stack: clear the undo stack */
 133 void
 134 clear_undo_stack(void)
 135 {
 136         line_t *lp, *ep, *tl;
 137
 138         while (u_p--)
 139                 if (ustack[u_p].type == UDEL) {
 140                         ep = ustack[u_p].t->q_forw;
 141                         for (lp = ustack[u_p].h; lp != ep; lp = tl) {
 142                                 unmark_line_node(lp);
 143                                 tl = lp->q_forw;
 144                                 free(lp);
 145                         }
 146                 }
 147         u_p = 0;
 148         u_current_addr = current_addr;
 149         u_addr_last = addr_last;
 150 }