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undo.c revision 1.2 
      1 /*	$NetBSD: undo.c,v 1.2 1995/03/21 09:04:52 cgd 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 #ifndef lint
     31 #if 0
     32 static char *rcsid = "@(#)undo.c,v 1.1 1994/02/01 00:34:44 alm Exp";
     33 #else
     34 static char rcsid[] = "$NetBSD: undo.c,v 1.2 1995/03/21 09:04:52 cgd Exp $";
     35 #endif
     36 #endif /* not lint */
     37 
     38 #include "ed.h"
     39 
     40 
     41 #define USIZE 100				/* undo stack size */
     42 undo_t *ustack = NULL;				/* undo stack */
     43 long usize = 0;					/* stack size variable */
     44 long u_p = 0;					/* undo stack pointer */
     45 
     46 /* push_undo_stack: return pointer to intialized undo node */
     47 undo_t *
     48 push_undo_stack(type, from, to)
     49 	int type;
     50 	long from;
     51 	long to;
     52 {
     53 	undo_t *t;
     54 
     55 #if defined(sun) || defined(NO_REALLOC_NULL)
     56 	if (ustack == NULL &&
     57 	    (ustack = (undo_t *) malloc((usize = USIZE) * sizeof(undo_t))) == NULL) {
     58 		fprintf(stderr, "%s\n", strerror(errno));
     59 		sprintf(errmsg, "out of memory");
     60 		return NULL;
     61 	}
     62 #endif
     63 	t = ustack;
     64 	if (u_p < usize ||
     65 	    (t = (undo_t *) realloc(ustack, (usize += USIZE) * sizeof(undo_t))) != NULL) {
     66 		ustack = t;
     67 		ustack[u_p].type = type;
     68 		ustack[u_p].t = get_addressed_line_node(to);
     69 		ustack[u_p].h = get_addressed_line_node(from);
     70 		return ustack + u_p++;
     71 	}
     72 	/* out of memory - release undo stack */
     73 	fprintf(stderr, "%s\n", strerror(errno));
     74 	sprintf(errmsg, "out of memory");
     75 	clear_undo_stack();
     76 	free(ustack);
     77 	ustack = NULL;
     78 	usize = 0;
     79 	return NULL;
     80 }
     81 
     82 
     83 /* USWAP: swap undo nodes */
     84 #define USWAP(x,y) { \
     85 	undo_t utmp; \
     86 	utmp = x, x = y, y = utmp; \
     87 }
     88 
     89 
     90 long u_current_addr = -1;	/* if >= 0, undo enabled */
     91 long u_addr_last = -1;		/* if >= 0, undo enabled */
     92 
     93 /* pop_undo_stack: undo last change to the editor buffer */
     94 int
     95 pop_undo_stack()
     96 {
     97 	long n;
     98 	long o_current_addr = current_addr;
     99 	long o_addr_last = addr_last;
    100 
    101 	if (u_current_addr == -1 || u_addr_last == -1) {
    102 		sprintf(errmsg, "nothing to undo");
    103 		return ERR;
    104 	} else if (u_p)
    105 		modified = 1;
    106 	get_addressed_line_node(0);	/* this get_addressed_line_node last! */
    107 	SPL1();
    108 	for (n = u_p; n-- > 0;) {
    109 		switch(ustack[n].type) {
    110 		case UADD:
    111 			REQUE(ustack[n].h->q_back, ustack[n].t->q_forw);
    112 			break;
    113 		case UDEL:
    114 			REQUE(ustack[n].h->q_back, ustack[n].h);
    115 			REQUE(ustack[n].t, ustack[n].t->q_forw);
    116 			break;
    117 		case UMOV:
    118 		case VMOV:
    119 			REQUE(ustack[n - 1].h, ustack[n].h->q_forw);
    120 			REQUE(ustack[n].t->q_back, ustack[n - 1].t);
    121 			REQUE(ustack[n].h, ustack[n].t);
    122 			n--;
    123 			break;
    124 		default:
    125 			/*NOTREACHED*/
    126 			;
    127 		}
    128 		ustack[n].type ^= 1;
    129 	}
    130 	/* reverse undo stack order */
    131 	for (n = u_p; n-- > (u_p + 1)/ 2;)
    132 		USWAP(ustack[n], ustack[u_p - 1 - n]);
    133 	if (isglobal)
    134 		clear_active_list();
    135 	current_addr = u_current_addr, u_current_addr = o_current_addr;
    136 	addr_last = u_addr_last, u_addr_last = o_addr_last;
    137 	SPL0();
    138 	return 0;
    139 }
    140 
    141 
    142 /* clear_undo_stack: clear the undo stack */
    143 void
    144 clear_undo_stack()
    145 {
    146 	line_t *lp, *ep, *tl;
    147 
    148 	while (u_p--)
    149 		if (ustack[u_p].type == UDEL) {
    150 			ep = ustack[u_p].t->q_forw;
    151 			for (lp = ustack[u_p].h; lp != ep; lp = tl) {
    152 				unmark_line_node(lp);
    153 				tl = lp->q_forw;
    154 				free(lp);
    155 			}
    156 		}
    157 	u_p = 0;
    158 	u_current_addr = current_addr;
    159 	u_addr_last = addr_last;
    160 }
    161