Convenient macro to check whether the buffer is hidden.

* buffer.h (BUFFER_HIDDEN_P): New macro.
* frame.c (make_frame): Use it.  Adjust comment.
* buffer.c (candidate_buffer): New function.
(Fother_buffer, other_buffer_safely): Use it.

4 files changed, 30 insertions, 16 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 2a138bfcf65..5c92d94ee64 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2012-12-07  Dmitry Antipov  <dmantipov@yandex.ru>
+
+        Convenient macro to check whether the buffer is hidden.
+        * buffer.h (BUFFER_HIDDEN_P): New macro.
+        * frame.c (make_frame): Use it.  Adjust comment.
+        * buffer.c (candidate_buffer): New function.
+        (Fother_buffer, other_buffer_safely): Use it.
+
 2012-12-06  Eli Zaretskii  <eliz@gnu.org>
 
         * w32proc.c (waitpid): Avoid busy-waiting when called with WNOHANG
diff --git a/src/buffer.c b/src/buffer.c
index 619a729a859..6e2191dc22f 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1529,6 +1529,16 @@ This does not change the name of the visited file (if any).  */)
   return BVAR (current_buffer, name);
 }
 
+/* True if B can be used as 'other-than-BUFFER' buffer.  */
+
+static bool
+candidate_buffer (Lisp_Object b, Lisp_Object buffer)
+{
+  return (BUFFERP (b) && !EQ (b, buffer)
+          && BUFFER_LIVE_P (XBUFFER (b))
+          && !BUFFER_HIDDEN_P (XBUFFER (b)));
+}
+          
 DEFUN ("other-buffer", Fother_buffer, Sother_buffer, 0, 3, 0,
        doc: /* Return most recently selected buffer other than BUFFER.
 Buffers not visible in windows are preferred to visible buffers, unless
@@ -1550,9 +1560,7 @@ exists, return the buffer `*scratch*' (creating it if necessary).  */)
   for (; CONSP (tail); tail = XCDR (tail))
     {
       buf = XCAR (tail);
-      if (BUFFERP (buf) && !EQ (buf, buffer)
-          && BUFFER_LIVE_P (XBUFFER (buf))
-          && (SREF (BVAR (XBUFFER (buf), name), 0) != ' ')
+      if (candidate_buffer (buf, buffer)
           /* If the frame has a buffer_predicate, disregard buffers that
              don't fit the predicate.  */
           && (NILP (pred) || !NILP (call1 (pred, buf))))
@@ -1570,9 +1578,7 @@ exists, return the buffer `*scratch*' (creating it if necessary).  */)
   for (; CONSP (tail); tail = XCDR (tail))
     {
       buf = Fcdr (XCAR (tail));
-      if (BUFFERP (buf) && !EQ (buf, buffer)
-          && BUFFER_LIVE_P (XBUFFER (buf))
-          && (SREF (BVAR (XBUFFER (buf), name), 0) != ' ')
+      if (candidate_buffer (buf, buffer)
           /* If the frame has a buffer_predicate, disregard buffers that
              don't fit the predicate.  */
           && (NILP (pred) || !NILP (call1 (pred, buf))))
@@ -1608,13 +1614,10 @@ other_buffer_safely (Lisp_Object buffer)
 {
   Lisp_Object tail, buf;
 
-  tail = Vbuffer_alist;
-  for (; CONSP (tail); tail = XCDR (tail))
+  for (tail = Vbuffer_alist; CONSP (tail); tail = XCDR (tail))
     {
       buf = Fcdr (XCAR (tail));
-      if (BUFFERP (buf) && !EQ (buf, buffer)
-          && BUFFER_LIVE_P (XBUFFER (buf))
-          && (SREF (BVAR (XBUFFER (buf), name), 0) != ' '))
+      if (candidate_buffer (buf, buffer))
         return buf;
     }
 
diff --git a/src/buffer.h b/src/buffer.h
index fbbbf1b8434..1129840bd47 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -982,6 +982,11 @@ bset_width_table (struct buffer *b, Lisp_Object val)
 
 #define BUFFER_LIVE_P(b) (!NILP (BVAR (b, name)))
 
+/* Convenient check whether buffer B is hidden (i.e. its name
+   starts with a space).  Caller must ensure that B is live.  */
+
+#define BUFFER_HIDDEN_P(b) (SREF (BVAR (b, name), 0) == ' ')
+
 /* Verify indirection counters.  */
 
 #define BUFFER_CHECK_INDIRECTION(b)                     \
diff --git a/src/frame.c b/src/frame.c
index ce9ae45eb90..87b21d0a41c 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -346,13 +346,11 @@ make_frame (int mini_p)
 
   /* Choose a buffer for the frame's root window.  */
   {
-    Lisp_Object buf;
+    Lisp_Object buf = Fcurrent_buffer ();
 
     wset_buffer (XWINDOW (root_window), Qt);
-    buf = Fcurrent_buffer ();
-    /* If buf is a 'hidden' buffer (i.e. one whose name starts with
-       a space), try to find another one.  */
-    if (SREF (Fbuffer_name (buf), 0) == ' ')
+    /* If current buffer is hidden, try to find another one.  */
+    if (BUFFER_HIDDEN_P (XBUFFER (buf)))
       buf = other_buffer_safely (buf);
 
     /* Use set_window_buffer, not Fset_window_buffer, and don't let