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