From 2b21a98e9c0e842bd2a66e18ff82b952a494e75c Mon Sep 17 00:00:00 2001
From: Renaud Fivet <renaud.fivet@gmail.com>
Date: Thu, 19 May 2016 21:27:26 +0800
Subject: [PATCH] Review forwchar and backchar.

---
 ebind.c  | 14 +++++-----
 line.c   | 83 +++++++++++++++++++++++++++++---------------------------
 line.h   |  4 +--
 names.c  |  4 +--
 random.c |  2 +-
 5 files changed, 55 insertions(+), 52 deletions(-)

diff --git a/ebind.c b/ebind.c
index f3a2ad9..aba7853 100644
--- a/ebind.c
+++ b/ebind.c
@@ -37,7 +37,7 @@
 struct key_tab keytab[NBINDS] = {
     {CONTROL | 'A', gotobol}
     ,
-    {CONTROL | 'B', backchar}
+    {CONTROL | 'B', (fn_t) backchar}
     ,
     {CONTROL | 'C', insspace}
     ,
@@ -45,7 +45,7 @@ struct key_tab keytab[NBINDS] = {
     ,
     {CONTROL | 'E', gotoeol}
     ,
-    {CONTROL | 'F', forwchar}
+    {CONTROL | 'F', (fn_t) forwchar}
     ,
     {CONTROL | 'G', ctrlg}
     ,
@@ -329,9 +329,9 @@ struct key_tab keytab[NBINDS] = {
     ,
     {SPEC | 73, backpage}
     ,
-    {SPEC | 75, backchar}
+    {SPEC | 75, (fn_t) backchar}
     ,
-    {SPEC | 77, forwchar}
+    {SPEC | 77, (fn_t) forwchar}
     ,
     {SPEC | 79, gotoeol}
     ,
@@ -406,13 +406,13 @@ struct key_tab keytab[NBINDS] = {
     ,
     {SPEC | 'B', forwline}
     ,
-    {SPEC | 'C', forwchar}
+    {SPEC | 'C', (fn_t) forwchar}
     ,
-    {SPEC | 'D', backchar}
+    {SPEC | 'D', (fn_t) backchar}
     ,
     {SPEC | 'c', metafn}
     ,
-    {SPEC | 'd', backchar}
+    {SPEC | 'd', (fn_t) backchar}
     ,
     {SPEC | 'e', forwline}
     ,
diff --git a/line.c b/line.c
index f3c59a0..f085b8c 100644
--- a/line.c
+++ b/line.c
@@ -91,16 +91,38 @@ char *getkill( void) {
  * location. Error if you try and move out of the buffer. Set the flag if the
  * line pointer for dot changes.
  */
-int backchar( int f, int n) {
+static unsigned utf8_revdelta( unsigned char *p, unsigned pos) {
+	unsigned delta = 0 ;
+
+	if( (*p & 0xC0) == 0x80) {
+		unsigned char c ;
+
+		c = *--p ;
+		if( (c & 0xE0) == 0xC0)	/* valid 2 bytes unicode seq */
+			delta = 1 ;
+		else if( ((c & 0xC0) == 0x80) && (pos > 1)) {
+			c = *--p ;
+			if( (c & 0xF0) == 0xE0)	/* valid 3 bytes unicode seq */
+				delta = 2 ;
+			else if( ((c & 0xC0) == 0x80) && (pos > 2))
+				if( (p[ -1] & 0xF8) == 0xF0)	/* valid 4 bytes unicode seq */
+					delta = 3 ;
+		}
+	}
+
+	return delta ;
+}
+
+boolean backchar( int f, int n) {
 	if( n < 0)
 		return forwchar( f, -n) ;
 
 	while( n--) {
-		if( curwp->w_doto == 0) {
-			struct line *lp ;
+		if( curwp->w_doto == 0) {	/* at beginning of line */
+			line_p lp ;
 
 			lp = lback( curwp->w_dotp) ;
-			if( lp == curbp->b_linep)
+			if( lp == curbp->b_linep)	/* at beginning of buffer */
 				return FALSE ;
 
 			curwp->w_dotp = lp ;
@@ -110,29 +132,8 @@ int backchar( int f, int n) {
 			unsigned pos ;
 			
 			pos = curwp->w_doto -= 1 ;
-			if( pos > 0) {
-				unsigned char *p ;
-
-				p = (unsigned char *) &( (curwp->w_dotp)->l_text[ pos]) ;
-				if( (*p & 0xC0) == 0x80) {
-					unsigned char c ;
-					int delta = 0 ;
-
-					c = *--p ;
-					if( (c & 0xE0) == 0xC0)	/* valid 2 bytes unicode seq */
-						delta = 1 ;
-					else if( ((c & 0xC0) == 0x80) && (pos > 1)) {
-						c = *--p ;
-						if( (c & 0xF0) == 0xE0)	/* valid 3 bytes unicode seq */
-							delta = 2 ;
-						else if( ((c & 0xC0) == 0x80) && (pos > 2))
-							if( (p[ -1] & 0xF8) == 0xF0)	/* valid 4 bytes unicode seq */
-								delta = 3 ;
-					}
-
-					curwp->w_doto -= delta ;
-				}
-			}
+			if( pos > 0)
+				curwp->w_doto -= utf8_revdelta( (unsigned char *) &( (curwp->w_dotp)->l_text[ pos]), pos) ;
 		}
 	}
 
@@ -145,18 +146,19 @@ int backchar( int f, int n) {
  * location, and move ".". Error if you try and move off the end of the
  * buffer. Set the flag if the line pointer for dot changes.
  */
-int forwchar(int f, int n)
-{
-	if (n < 0)
-		return backchar(f, -n);
-	while (n--) {
-		int len = llength(curwp->w_dotp);
-		if (curwp->w_doto == len) {
-			if (curwp->w_dotp == curbp->b_linep)
-				return FALSE;
-			curwp->w_dotp = lforw(curwp->w_dotp);
-			curwp->w_doto = 0;
-			curwp->w_flag |= WFMOVE;
+boolean forwchar( int f, int n) {
+	if( n < 0)
+		return backchar( f, -n) ;
+
+	while( n--) {
+		int len = llength( curwp->w_dotp) ;
+		if( curwp->w_doto == len) {	/* at end of line */
+			if( curwp->w_dotp == curbp->b_linep)	/* at end of buffer */
+				return FALSE ;
+
+			curwp->w_dotp = lforw( curwp->w_dotp) ;
+			curwp->w_doto = 0 ;
+			curwp->w_flag |= WFMOVE ;
 		} else {
 			unicode_t unc ;
 			unsigned bytes ;
@@ -165,7 +167,8 @@ int forwchar(int f, int n)
 			curwp->w_doto += bytes ;
 		}
 	}
-	return TRUE;
+
+	return TRUE ;
 }
 
 /*
diff --git a/line.h b/line.h
index e082e1d..fb88741 100644
--- a/line.h
+++ b/line.h
@@ -30,8 +30,8 @@ extern int tabwidth ;	/* Map to $tab, default to 8, can be set to [1, .. */
 
 char *getkill( void) ;
 
-int backchar( int f, int n) ;
-int forwchar( int f, int n) ;
+boolean backchar( int f, int n) ;
+boolean forwchar( int f, int n) ;
 
 void lfree( line_p lp) ;
 void lchange( int flag) ;
diff --git a/names.c b/names.c
index ea6b22b..f44bfb7 100644
--- a/names.c
+++ b/names.c
@@ -34,7 +34,7 @@ struct name_bind names[] = {
 #if	APROP
 	{"apropos", apro},
 #endif
-	{"backward-character", backchar},
+	{"backward-character", (fn_t) backchar},
 	{"begin-macro", ctlxlp},
 	{"beginning-of-file", gotobob},
 	{"beginning-of-line", gotobol},
@@ -132,7 +132,7 @@ struct name_bind names[] = {
 #endif
 	{"filter-buffer", filter_buffer},
 	{"find-file", filefind},
-	{"forward-character", forwchar},
+	{"forward-character", (fn_t) forwchar},
 	{"goto-line", gotoline},
 #if	CFENCE
 	{"goto-matching-fence", getfence},
diff --git a/random.c b/random.c
index 70eabb7..d0e239f 100644
--- a/random.c
+++ b/random.c
@@ -705,7 +705,7 @@ int backdel( int f, int n) {
 		thisflag |= CFKILL;
 	}
 
-	return (backchar( f, n) == TRUE) && ldelchar( n, f != FALSE) ;
+	return backchar( f, n) && ldelchar( n, f != FALSE) ;
 }
 
 /*