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 const char rcsid[] = 30 "$FreeBSD$"; 31 #endif /* not lint */ 32 33 #include "ed.h" 34 35 36 #define USIZE 100 /* undo stack size */ 37 undo_t *ustack = NULL; /* undo stack */ 38 long usize = 0; /* stack size variable */ 39 long u_p = 0; /* undo stack pointer */ 40 41 /* push_undo_stack: return pointer to initialized undo node */ 42 undo_t * 43 push_undo_stack(int type, long from, long to) 44 { 45 undo_t *t; 46 47 #if defined(sun) || defined(NO_REALLOC_NULL) 48 if (ustack == NULL && 49 (ustack = (undo_t *) malloc((usize = USIZE) * sizeof(undo_t))) == NULL) { 50 fprintf(stderr, "%s\n", strerror(errno)); 51 errmsg = "out of memory"; 52 return NULL; 53 } 54 #endif 55 t = ustack; 56 if (u_p < usize || 57 (t = (undo_t *) realloc(ustack, (usize += USIZE) * sizeof(undo_t))) != NULL) { 58 ustack = t; 59 ustack[u_p].type = type; 60 ustack[u_p].t = get_addressed_line_node(to); 61 ustack[u_p].h = get_addressed_line_node(from); 62 return ustack + u_p++; 63 } 64 /* out of memory - release undo stack */ 65 fprintf(stderr, "%s\n", strerror(errno)); 66 errmsg = "out of memory"; 67 clear_undo_stack(); 68 free(ustack); 69 ustack = NULL; 70 usize = 0; 71 return NULL; 72 } 73 74 75 /* USWAP: swap undo nodes */ 76 #define USWAP(x,y) { \ 77 undo_t utmp; \ 78 utmp = x, x = y, y = utmp; \ 79 } 80 81 82 long u_current_addr = -1; /* if >= 0, undo enabled */ 83 long u_addr_last = -1; /* if >= 0, undo enabled */ 84 85 /* pop_undo_stack: undo last change to the editor buffer */ 86 int 87 pop_undo_stack(void) 88 { 89 long n; 90 long o_current_addr = current_addr; 91 long o_addr_last = addr_last; 92 93 if (u_current_addr == -1 || u_addr_last == -1) { 94 errmsg = "nothing to undo"; 95 return ERR; 96 } else if (u_p) 97 modified = 1; 98 get_addressed_line_node(0); /* this get_addressed_line_node last! */ 99 SPL1(); 100 for (n = u_p; n-- > 0;) { 101 switch(ustack[n].type) { 102 case UADD: 103 REQUE(ustack[n].h->q_back, ustack[n].t->q_forw); 104 break; 105 case UDEL: 106 REQUE(ustack[n].h->q_back, ustack[n].h); 107 REQUE(ustack[n].t, ustack[n].t->q_forw); 108 break; 109 case UMOV: 110 case VMOV: 111 REQUE(ustack[n - 1].h, ustack[n].h->q_forw); 112 REQUE(ustack[n].t->q_back, ustack[n - 1].t); 113 REQUE(ustack[n].h, ustack[n].t); 114 n--; 115 break; 116 default: 117 /*NOTREACHED*/ 118 ; 119 } 120 ustack[n].type ^= 1; 121 } 122 /* reverse undo stack order */ 123 for (n = u_p; n-- > (u_p + 1)/ 2;) 124 USWAP(ustack[n], ustack[u_p - 1 - n]); 125 if (isglobal) 126 clear_active_list(); 127 current_addr = u_current_addr, u_current_addr = o_current_addr; 128 addr_last = u_addr_last, u_addr_last = o_addr_last; 129 SPL0(); 130 return 0; 131 } 132 133 134 /* clear_undo_stack: clear the undo stack */ 135 void 136 clear_undo_stack(void) 137 { 138 line_t *lp, *ep, *tl; 139 140 while (u_p--) 141 if (ustack[u_p].type == UDEL) { 142 ep = ustack[u_p].t->q_forw; 143 for (lp = ustack[u_p].h; lp != ep; lp = tl) { 144 unmark_line_node(lp); 145 tl = lp->q_forw; 146 free(lp); 147 } 148 } 149 u_p = 0; 150 u_current_addr = current_addr; 151 u_addr_last = addr_last; 152 } 153