built-in add -p: offer a helpful error message when hunk navigation failed

... just like the Perl version currently does...

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/add-patch.c b/add-patch.c
index dab2ff2381f0642488db2ebd79f0e4083ce0d97e..f59471cdf27d06899785d7499ac3a968f8093554 100644 (file)
--- a/add-patch.c
+++ b/add-patch.c
@@ -34,6 +34,18 @@ struct add_p_state {
        size_t hunk_nr, hunk_alloc;
 };
 
+static void err(struct add_p_state *s, const char *fmt, ...)
+{
+       va_list args;
+
+       va_start(args, fmt);
+       fputs(s->s.error_color, stderr);
+       vfprintf(stderr, fmt, args);
+       fputs(s->s.reset_color, stderr);
+       fputc('\n', stderr);
+       va_end(args);
+}
+
 static void setup_child_process(struct add_p_state *s,
                                struct child_process *cp, ...)
 {
@@ -368,17 +380,27 @@ soft_increment:
                                if (hunk->use == UNDECIDED_HUNK)
                                        hunk->use = SKIP_HUNK;
                        }
-               } else if (hunk_index && s->answer.buf[0] == 'K')
-                       hunk_index--;
-               else if (hunk_index + 1 < s->hunk_nr &&
-                        s->answer.buf[0] == 'J')
-                       hunk_index++;
-               else if (undecided_previous >= 0 &&
-                        s->answer.buf[0] == 'k')
-                       hunk_index = undecided_previous;
-               else if (undecided_next >= 0 && s->answer.buf[0] == 'j')
-                       hunk_index = undecided_next;
-               else
+               } else if (s->answer.buf[0] == 'K') {
+                       if (hunk_index)
+                               hunk_index--;
+                       else
+                               err(s, _("No previous hunk"));
+               } else if (s->answer.buf[0] == 'J') {
+                       if (hunk_index + 1 < s->hunk_nr)
+                               hunk_index++;
+                       else
+                               err(s, _("No next hunk"));
+               } else if (s->answer.buf[0] == 'k') {
+                       if (undecided_previous >= 0)
+                               hunk_index = undecided_previous;
+                       else
+                               err(s, _("No previous hunk"));
+               } else if (s->answer.buf[0] == 'j') {
+                       if (undecided_next >= 0)
+                               hunk_index = undecided_next;
+                       else
+                               err(s, _("No next hunk"));
+               } else
                        color_fprintf(stdout, s->s.help_color,
                                      _(help_patch_text));
        }