1 /*- 2 * Copyright (c) 1992, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (c) 1992, 1993, 1994, 1995, 1996 5 * Keith Bostic. All rights reserved. 6 * 7 * See the LICENSE file for redistribution information. 8 */ 9 10 #include "config.h" 11 12 #ifndef lint 13 static const char sccsid[] = "@(#)ex_undo.c 10.6 (Berkeley) 3/6/96"; 14 #endif /* not lint */ 15 16 #include <sys/types.h> 17 #include <sys/queue.h> 18 19 #include <bitstring.h> 20 #include <limits.h> 21 #include <stdio.h> 22 #include <stdlib.h> 23 24 #include "../common/common.h" 25 26 /* 27 * ex_undo -- u 28 * Undo the last change. 29 * 30 * PUBLIC: int ex_undo __P((SCR *, EXCMD *)); 31 */ 32 int 33 ex_undo(sp, cmdp) 34 SCR *sp; 35 EXCMD *cmdp; 36 { 37 EXF *ep; 38 MARK m; 39 40 /* 41 * !!! 42 * Historic undo always set the previous context mark. 43 */ 44 m.lno = sp->lno; 45 m.cno = sp->cno; 46 if (mark_set(sp, ABSMARK1, &m, 1)) 47 return (1); 48 49 /* 50 * !!! 51 * Multiple undo isn't available in ex, as there's no '.' command. 52 * Whether 'u' is undo or redo is toggled each time, unless there 53 * was a change since the last undo, in which case it's an undo. 54 */ 55 ep = sp->ep; 56 if (!F_ISSET(ep, F_UNDO)) { 57 F_SET(ep, F_UNDO); 58 ep->lundo = FORWARD; 59 } 60 switch (ep->lundo) { 61 case BACKWARD: 62 if (log_forward(sp, &m)) 63 return (1); 64 ep->lundo = FORWARD; 65 break; 66 case FORWARD: 67 if (log_backward(sp, &m)) 68 return (1); 69 ep->lundo = BACKWARD; 70 break; 71 case NOTSET: 72 abort(); 73 } 74 sp->lno = m.lno; 75 sp->cno = m.cno; 76 return (0); 77 } 78