add reverse search command N

5 files changed, 18 insertions, 17 deletions

diff --git a/edit.c b/edit.c
index bb6b171..067d4f0 100644
--- a/edit.c
+++ b/edit.c
@@ -344,18 +344,19 @@ eb_getmark(EBuf *eb, Rune name)
 }
 
 unsigned
-eb_look(EBuf *eb, unsigned p, Rune *str, unsigned n)
+eb_look(EBuf *eb, unsigned p0, Rune *str, unsigned n, int rev)
 {
-	unsigned i, j;
+	unsigned i, j, l, x;
 
 	assert(str);
 
-	while (p<eb->b.limbo) {
-		i = p++;
+	l = eb->b.limbo;
+	for (x=1; x<l; x++) {
+		i = (p0 + (rev ? l-x : x)) % l;
 		j = 0;
 		while (buf_get(&eb->b, i++) == str[j++])
 			if (j == n)
-				return p-1;
+				return i-n;
 	}
 	return -1u;
 }
diff --git a/edit.h b/edit.h
index 0983020..752fa02 100644
--- a/edit.h
+++ b/edit.h
@@ -39,5 +39,5 @@ void eb_undo(EBuf *, int, unsigned *);
 void eb_yank(EBuf *, unsigned, unsigned, YBuf *);
 void eb_setmark(EBuf *, Rune, unsigned);
 unsigned eb_getmark(EBuf *, Rune);
-unsigned eb_look(EBuf *, unsigned, Rune *, unsigned);
+unsigned eb_look(EBuf *, unsigned, Rune *, unsigned, int);
 void eb_write(EBuf *, int);
diff --git a/exec.c b/exec.c
index da95c70..4e9e1b8 100644
--- a/exec.c
+++ b/exec.c
@@ -83,18 +83,17 @@ ex_run(W *w, unsigned p0)
 
 /* ex_look - Look for a string [s] in window [w] and jump
  * to the first match after the cursor position.  The caller
- * is responsible to free the [s] buffer.
+ * is responsible to free the [s] buffer.  If [rev] is true
+ * the search goes backward.
  */
 int
-ex_look(W *w, Rune *s, unsigned n)
+ex_look(W *w, Rune *s, unsigned n, int rev)
 {
 	unsigned p;
 
 	if (n == 0)
 		return 1;
-	p = eb_look(w->eb, w->cu+1, s, n);
-	if (p == -1u)
-		p = eb_look(w->eb, 0, s, n);
+	p = eb_look(w->eb, w->cu, s, n, rev);
 	if (p != -1u) {
 		w->cu = p;
 		eb_setmark(w->eb, SelBeg, p);
@@ -351,7 +350,7 @@ look(W *w, EBuf *eb, unsigned p0)
 		return 0;
 	p1 = 1 + skipb(&eb->b, buf_eol(&eb->b, p0) - 1, -1);
 	eb_yank(eb, p0, p1, &b);
-	e = ex_look(w, b.r, b.nr);
+	e = ex_look(w, b.r, b.nr, 0);
 	free(b.r);
 	if (e) {
 		err(eb, p0, errstr);
diff --git a/exec.h b/exec.h
index 1da01a3..677968d 100644
--- a/exec.h
+++ b/exec.h
@@ -1,5 +1,5 @@
 int ex_run(W *, unsigned);
-int ex_look(W *, Rune *, unsigned);
+int ex_look(W *, Rune *, unsigned, int);
 int ex_put(EBuf *, char *);
 int ex_get(W *, char *);
 void ex_cancel(Task *);
diff --git a/vicmd.w b/vicmd.w
index add0cba..4df8c66 100644
--- a/vicmd.w
+++ b/vicmd.w
@@ -858,7 +858,7 @@ the annonymous yank buffer.  When a match is found the selection
 is set to the matched text.  If the search hits limbo it wraps around.
 
 @<Subr...@>=
-static int m_n(int ismotion, Cmd c, Motion *m)
+static int m_nN(int ismotion, Cmd c, Motion *m)
 {
 	YBuf b = {0, 0, 0, 0}, *pb = &yannon;
 	int err = 0;
@@ -869,7 +869,7 @@ static int m_n(int ismotion, Cmd c, Motion *m)
 	if (s0 < s1 && s0 != -1u && s1 != -1u)
 		eb_yank(curwin->eb, s0, s1, pb = &b);
 	while (c.count--)
-		err |= ex_look(curwin, pb->r, pb->nr);
+		err |= ex_look(curwin, pb->r, pb->nr, c.chr == 'N');
 	free(b.r);
 	m->end = curwin->cu;
 	if (ismotion)
@@ -878,7 +878,7 @@ static int m_n(int ismotion, Cmd c, Motion *m)
 }
 
 @ @<Predecl...@>=
-static int m_n(int, Cmd, Motion *);
+static int m_nN(int, Cmd, Motion *);
 
 @ Because the search functionality is different, the \./ command is free
 to use.  We reuse it as a motion that designates the whole selection.
@@ -1306,7 +1306,8 @@ union {
 ['%'] = Mtn(0, m_match), ['G'] = Mtn(CZeroCount, m_G),@/
 ['H'] = Mtn(0, m_HML), ['L'] = Mtn(0, m_HML),@/
 ['M'] = Mtn(0, m_HML),@/
-['n'] = Mtn(0, m_n), ['/'] = Mtn(0, m_sel),@/
+['n'] = Mtn(0, m_nN), ['N'] = Mtn(0, m_nN),@/
+['/'] = Mtn(0, m_sel),@/
 ['\''] = Mtn(CHasArg, m_mark), ['`'] = Mtn(CHasArg, m_mark),@/
 ['d'] = Act(CHasMotion, a_d), ['x'] = Act(0, a_d),@/
 ['c'] = Act(CHasMotion, a_c), ['y'] = Act(CHasMotion, a_y),@/