unf*ck undo.

No seriously. Reposition the cursor to the start of the redo
position, like emacs. This gets us halfway to being emacs-finger-friendly.
For the rest, introduce a rptcount variable to count successive invocations
of the same function. This means undo will abort properly on C-g, and
other such interruptions.
This is a lot of diff for a simple-seeming problem. Emacs undo is hard.

3 files changed, 50 insertions, 14 deletions

diff --git a/usr.bin/mg/def.h b/usr.bin/mg/def.h
index bd3b8ce677f..451d792829f 100644
--- a/usr.bin/mg/def.h
+++ b/usr.bin/mg/def.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: def.h,v 1.104 2008/06/13 19:10:17 kjell Exp $	*/
+/*	$OpenBSD: def.h,v 1.105 2008/06/14 07:38:53 kjell Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -668,3 +668,4 @@ extern char		 prompt[];
 int		 tceeol;
 int		 tcinsl;
 int		 tcdell;
+int		 rptcount;	/* successive invocation count */
diff --git a/usr.bin/mg/kbd.c b/usr.bin/mg/kbd.c
index 0d75c1c68b5..c0bd9e836aa 100644
--- a/usr.bin/mg/kbd.c
+++ b/usr.bin/mg/kbd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kbd.c,v 1.23 2006/12/21 18:06:02 kjell Exp $	*/
+/*	$OpenBSD: kbd.c,v 1.24 2008/06/14 07:38:53 kjell Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -23,6 +23,8 @@
 char	 prompt[PROMPTL] = "", *promptp = prompt;
 #endif /* !NO_DPROMPT */
 
+static int mgwrap(PF, int, int);
+
 static int	 use_metakey = TRUE;
 static int	 pushed = FALSE;
 static int	 pushedc;
@@ -162,7 +164,7 @@ doin(void)
 	if (macrodef && macrocount < MAXMACRO)
 		macro[macrocount++].m_funct = funct;
 #endif /* !NO_MACRO */
-	return ((*funct)(0, 1));
+	return (mgwrap(funct, 0, 1));
 }
 
 int
@@ -179,8 +181,8 @@ rescan(int f, int n)
 			c = TOLOWER(key.k_chars[key.k_count - 1]);
 			curmap = curbp->b_modes[md]->p_map;
 			for (i = 0; i < key.k_count - 1; i++) {
-				if ((fp = doscan(curmap, (key.k_chars[i]), &curmap))
-				    != NULL)
+				if ((fp = doscan(curmap, (key.k_chars[i]),
+				    &curmap)) != NULL)
 					break;
 			}
 			if (fp == NULL) {
@@ -195,7 +197,8 @@ rescan(int f, int n)
 						macro[macrocount - 1].m_funct
 						    = fp;
 #endif /* !NO_MACRO */
-					return ((*fp)(f, n));
+
+					return (mgwrap(fp, f, n));
 				}
 			}
 		}
@@ -218,7 +221,7 @@ rescan(int f, int n)
 			if (macrodef && macrocount <= MAXMACRO)
 				macro[macrocount - 1].m_funct = fp;
 #endif /* !NO_MACRO */
-			return ((*fp)(f, n));
+			return (mgwrap(fp, f, n));
 		}
 	}
 }
@@ -252,7 +255,7 @@ universal_argument(int f, int n)
 				macro[macrocount++].m_funct = funct;
 			}
 #endif /* !NO_MACRO */
-			return ((*funct)(FFUNIV, nn));
+			return (mgwrap(funct, FFUNIV, nn));
 		}
 		nn <<= 2;
 	}
@@ -290,7 +293,7 @@ digit_argument(int f, int n)
 		macro[macrocount++].m_funct = funct;
 	}
 #endif /* !NO_MACRO */
-	return ((*funct)(FFOTHARG, nn));
+	return (mgwrap(funct, FFOTHARG, nn));
 }
 
 int
@@ -328,7 +331,7 @@ negative_argument(int f, int n)
 		macro[macrocount++].m_funct = funct;
 	}
 #endif /* !NO_MACRO */
-	return ((*funct)(FFNEGARG, nn));
+	return (mgwrap(funct, FFNEGARG, nn));
 }
 
 /*
@@ -424,3 +427,27 @@ quote(int f, int n)
 	}
 	return (selfinsert(f, n));
 }
+
+/*
+ * Wraper function to count invocation repeats.
+ * We ignore any function whose sole purpose is to get us
+ * to the intended function.
+ */
+static int
+mgwrap(PF funct, int f, int n)
+{
+	static	 PF ofp;
+	
+	if (funct != rescan &&
+	    funct != negative_argument &&
+	    funct != digit_argument &&
+	    funct != universal_argument) {
+		if (funct == ofp)
+			rptcount++;
+		else
+			rptcount = 0;
+		ofp = funct;
+	}
+	
+	return ((*funct)(f, n));
+}
diff --git a/usr.bin/mg/undo.c b/usr.bin/mg/undo.c
index 4b8d1a25fbd..f4206a86a74 100644
--- a/usr.bin/mg/undo.c
+++ b/usr.bin/mg/undo.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: undo.c,v 1.45 2008/06/11 17:07:37 kjell Exp $ */
+/* $OpenBSD: undo.c,v 1.46 2008/06/14 07:38:53 kjell Exp $ */
 /*
  * This file is in the public domain
  */
@@ -173,7 +173,8 @@ undo_enable(int on)
 
 /*
  * If undo is enabled, then:
- *   undo_boundary_enable(FALS) stops recording undo boundaries between actions.
+ *   undo_boundary_enable(FALSE) stops recording undo boundaries
+ *   between actions.
  *   undo_boundary_enable(TRUE) enables undo boundaries.
  * If undo is disabled, this function has no effect.
  */
@@ -443,12 +444,15 @@ undo(int f, int n)
 	static int	 nulled = FALSE;
 	int		 lineno;
 
+	if (n < 0)
+		return (FALSE);
+
 	dot = find_dot(curwp->w_dotp, curwp->w_doto);
 
 	ptr = curbp->b_undoptr;
 
-	/* if we moved, make ptr point back to the top of the list */
-	if ((ptr == NULL && nulled == TRUE) || curbp->b_undopos != dot) {
+	/* first invocation, make ptr point back to the top of the list */
+	if ((ptr == NULL && nulled == TRUE) ||  rptcount == 0) {
 		ptr = LIST_FIRST(&curbp->b_undo);
 		nulled = TRUE;
 	}
@@ -515,8 +519,12 @@ undo(int f, int n)
 				ldelete(ptr->region.r_size, KNONE);
 				break;
 			case DELETE:
+				lp = curwp->w_dotp;
+				offset = curwp->w_doto;
 				region_put_data(ptr->content,
 				    ptr->region.r_size);
+				curwp->w_dotp = lp;
+				curwp->w_doto = offset;
 				break;
 			case BOUNDARY:
 				done = 1;