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 #include "ed.h" 30 31 32 #define USIZE 100 /* undo stack size */ 33 static undo_t *ustack = NULL; /* undo stack */ 34 static long usize = 0; /* stack size variable */ 35 static long u_p = 0; /* undo stack pointer */ 36 37 /* push_undo_stack: return pointer to initialized undo node */ 38 undo_t * 39 push_undo_stack(int type, long from, long to) 40 { 41 undo_t *t; 42 43 #if defined(sun) || defined(NO_REALLOC_NULL) 44 if (ustack == NULL && 45 (ustack = (undo_t *) malloc((usize = USIZE) * sizeof(undo_t))) == NULL) { 46 fprintf(stderr, "%s\n", strerror(errno)); 47 errmsg = "out of memory"; 48 return NULL; 49 } 50 #endif 51 t = ustack; 52 if (u_p < usize || 53 (t = (undo_t *) realloc(ustack, (usize += USIZE) * sizeof(undo_t))) != NULL) { 54 ustack = t; 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(errno)); 62 errmsg = "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 errmsg = "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