linenoise: improve efficiency of warning flash.

* linenoise/linenoise.c (usec_delay): return a Boolean
indicator whether the delay was prematurely canceled by input.
(flash): Use the return value of usec_delay to bail out of the
loop early, canceling the flashing.  Instead of doing full
line refreshes to display and hide the exclamation mark,
perform the flash by simply printing the exclamation mark at
the current location and then erasing it with
backspace-space-backspace.

1 files changed, 20 insertions, 12 deletions

diff --git a/linenoise/linenoise.c b/linenoise/linenoise.c
index 9bec8212..3aaf7b80 100644
--- a/linenoise/linenoise.c
+++ b/linenoise/linenoise.c
@@ -1366,24 +1366,28 @@ static int find_nearest_paren(const wchar_t *s, int i)
     return nxt;
 }
 
-static void usec_delay(lino_t *l, long usec)
+static int usec_delay(lino_t *l, long usec)
 {
 #if HAVE_POLL
     struct pollfd pfd;
+
     pfd.fd = lino_os.fileno_fn(l->tty_ifs);
     pfd.events = POLLIN;
-    poll(&pfd, 1, usec/1000);
+    pfd.revents = 0;
+    return poll(&pfd, 1, usec/1000) == 1;
 #elif HAVE_POSIX_NANOSLEEP
     struct timespec ts;
     (void) l;
     ts.tv_sec = usec / 1000000;
     ts.tv_nsec = (usec % 1000000) * 1000;
     nanosleep(&ts, 0);
+    return 0;
 #elif HAVE_POSIX_USLEEP
     (void) l;
     if (u >= 1000000)
         sleep(u / 1000000);
     usleep(u % 1000000);
+    return 0;
 #else
 #error portme
 #endif
@@ -1408,20 +1412,20 @@ static void paren_jump(lino_t *l)
 
 static void flash(lino_t *l, int ch)
 {
-    int i;
+    int i, cancel = 0;
+    wchar_t on[2] = { ch };
+    const wchar_t *off = L"\b \b";
 
     if (l->dlen >= (int) nelem (l->data) - 1)
         return;
 
-    for (i = 0; i < 2; i++) {
+    for (i = 0; i < 2 && !cancel; i++) {
         if (i > 0)
+            cancel = usec_delay(l, LINENOISE_FLASH_DELAY);
+        lino_os.puts_fn(l->tty_ofs, on);
+        if (!cancel)
             usec_delay(l, LINENOISE_FLASH_DELAY);
-        l->data[l->dlen++] = ch;
-        l->data[l->dlen] = 0;
-        refresh_line(l);
-        usec_delay(l, LINENOISE_FLASH_DELAY);
-        l->data[--l->dlen] = 0;
-        refresh_line(l);
+        lino_os.puts_fn(l->tty_ofs, off);
     }
 }
 
@@ -2090,8 +2094,10 @@ static int edit(lino_t *l, const wchar_t *prompt)
                         l->error = lino_ioerr;
                         goto out;
                     }
-                    if (l->dpos == l->dlen)
+                    if (l->dpos == l->dlen) {
+                        refresh_line(l);
                         flash(l, '!');
+                    }
                     break;
                 }
                 if (l->mlmode)
@@ -2155,8 +2161,10 @@ static int edit(lino_t *l, const wchar_t *prompt)
                     l->error = lino_ioerr;
                     goto out;
                 }
-                if (!paste && l->dpos == l->dlen)
+                if (!paste && l->dpos == l->dlen) {
+                    refresh_line(l);
                     flash(l, '!');
+                }
                 break;
             }
             if (l->mlmode)