Use zero_vector where appropriate.

* alloc.c (zero_vector): Define as Lisp_Object.  Adjust users
accordingly.
* lisp.h (zero_vector): New declaration.
* font.c (null_vector): Remove.
(syms_of_font): Remove initialization and staticpro.
(font_list_entities, font_find_for_lface): Change to use zero_vector.
* keymap.c (Faccessible_keymaps): Likewise.

5 files changed, 29 insertions, 27 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 67bbf0b5bb7..2a6f2ebb42b 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,14 @@
+2012-07-15  Dmitry Antipov  <dmantipov@yandex.ru>
+
+        Use zero_vector where appropriate.
+        * alloc.c (zero_vector): Define as Lisp_Object.  Adjust users
+        accordingly.
+        * lisp.h (zero_vector): New declaration.
+        * font.c (null_vector): Remove.
+        (syms_of_font): Remove initialization and staticpro.
+        (font_list_entities, font_find_for_lface): Change to use zero_vector.
+        * keymap.c (Faccessible_keymaps): Likewise.
+
 2012-07-15  Leo Liu  <sdl.web@gmail.com>
 
         * fringe.c: Fix typo in comments.
diff --git a/src/alloc.c b/src/alloc.c
index ac200254b8c..1df775a093b 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -2973,7 +2973,7 @@ static struct Lisp_Vector *large_vectors;
 
 /* The only vector with 0 slots, allocated from pure space.  */
 
-static struct Lisp_Vector *zero_vector;
+Lisp_Object zero_vector;
 
 /* Get a new vector block.  */
 
@@ -2997,8 +2997,7 @@ allocate_vector_block (void)
 static void
 init_vectors (void)
 {
-  zero_vector = pure_alloc (header_size, Lisp_Vectorlike);
-  zero_vector->header.size = 0;
+  zero_vector = make_pure_vector (0);
 }
 
 /* Allocate vector from a vector block.  */
@@ -3190,7 +3189,7 @@ allocate_vectorlike (ptrdiff_t len)
   /* eassert (!handling_signal); */
 
   if (len == 0)
-    p = zero_vector;
+    p = XVECTOR (zero_vector);
   else
     {
       size_t nbytes = header_size + len * word_size;
diff --git a/src/font.c b/src/font.c
index 74f58878391..5b01a1f44d6 100644
--- a/src/font.c
+++ b/src/font.c
@@ -59,10 +59,6 @@ Lisp_Object Qascii_0, Qiso8859_1, Qiso10646_1, Qunicode_bmp, Qunicode_sip;
 /* Unicode category `Cf'.  */
 static Lisp_Object QCf;
 
-/* Special vector of zero length.  This is repeatedly used by (struct
-   font_driver *)->list when a specified font is not found. */
-static Lisp_Object null_vector;
-
 /* Vector of Vfont_weight_table, Vfont_slant_table, and Vfont_width_table. */
 static Lisp_Object font_style_table;
 
@@ -2748,7 +2744,7 @@ font_list_entities (Lisp_Object frame, Lisp_Object spec)
 
             val = driver_list->driver->list (frame, scratch_font_spec);
             if (NILP (val))
-              val = null_vector;
+              val = zero_vector;
             else
               val = Fvconcat (1, &val);
             copy = copy_font_spec (scratch_font_spec);
@@ -3104,10 +3100,10 @@ font_find_for_lface (FRAME_PTR f, Lisp_Object *attrs, Lisp_Object spec, int c)
     {
       registry[0] = DEFAULT_ENCODING;
       registry[1] = Qascii_0;
-      registry[2] = null_vector;
+      registry[2] = zero_vector;
     }
   else
-    registry[1] = null_vector;
+    registry[1] = zero_vector;
 
   if (c >= 0 && ! NILP (AREF (spec, FONT_REGISTRY_INDEX)))
     {
@@ -3136,20 +3132,20 @@ font_find_for_lface (FRAME_PTR f, Lisp_Object *attrs, Lisp_Object spec, int c)
   ASET (work, FONT_SIZE_INDEX, Qnil);
   foundry[0] = AREF (work, FONT_FOUNDRY_INDEX);
   if (! NILP (foundry[0]))
-    foundry[1] = null_vector;
+    foundry[1] = zero_vector;
   else if (STRINGP (attrs[LFACE_FOUNDRY_INDEX]))
     {
       val = attrs[LFACE_FOUNDRY_INDEX];
       foundry[0] = font_intern_prop (SSDATA (val), SBYTES (val), 1);
       foundry[1] = Qnil;
-      foundry[2] = null_vector;
+      foundry[2] = zero_vector;
     }
   else
-    foundry[0] = Qnil, foundry[1] = null_vector;
+    foundry[0] = Qnil, foundry[1] = zero_vector;
 
   adstyle[0] = AREF (work, FONT_ADSTYLE_INDEX);
   if (! NILP (adstyle[0]))
-    adstyle[1] = null_vector;
+    adstyle[1] = zero_vector;
   else if (FONTP (attrs[LFACE_FONT_INDEX]))
     {
       Lisp_Object face_font = attrs[LFACE_FONT_INDEX];
@@ -3158,13 +3154,13 @@ font_find_for_lface (FRAME_PTR f, Lisp_Object *attrs, Lisp_Object spec, int c)
         {
           adstyle[0] = AREF (face_font, FONT_ADSTYLE_INDEX);
           adstyle[1] = Qnil;
-          adstyle[2] = null_vector;
+          adstyle[2] = zero_vector;
         }
       else
-        adstyle[0] = Qnil, adstyle[1] = null_vector;
+        adstyle[0] = Qnil, adstyle[1] = zero_vector;
     }
   else
-    adstyle[0] = Qnil, adstyle[1] = null_vector;
+    adstyle[0] = Qnil, adstyle[1] = zero_vector;
 
 
   val = AREF (work, FONT_FAMILY_INDEX);
@@ -3177,7 +3173,7 @@ font_find_for_lface (FRAME_PTR f, Lisp_Object *attrs, Lisp_Object spec, int c)
     {
       family = alloca ((sizeof family[0]) * 2);
       family[0] = Qnil;
-      family[1] = null_vector;  /* terminator.  */
+      family[1] = zero_vector;  /* terminator.  */
     }
   else
     {
@@ -3192,7 +3188,7 @@ font_find_for_lface (FRAME_PTR f, Lisp_Object *attrs, Lisp_Object spec, int c)
             family[i] = XCAR (alters);
           if (NILP (AREF (spec, FONT_FAMILY_INDEX)))
             family[i++] = Qnil;
-          family[i] = null_vector;
+          family[i] = zero_vector;
         }
       else
         {
@@ -3201,7 +3197,7 @@ font_find_for_lface (FRAME_PTR f, Lisp_Object *attrs, Lisp_Object spec, int c)
           family[i++] = val;
           if (NILP (AREF (spec, FONT_FAMILY_INDEX)))
             family[i++] = Qnil;
-          family[i] = null_vector;
+          family[i] = zero_vector;
         }
     }
 
@@ -5095,9 +5091,6 @@ syms_of_font (void)
 
   DEFSYM (QCuser_spec, "user-spec");
 
-  staticpro (&null_vector);
-  null_vector = Fmake_vector (make_number (0), Qnil);
-
   staticpro (&scratch_font_spec);
   scratch_font_spec = Ffont_spec (0, NULL);
   staticpro (&scratch_font_prefer);
diff --git a/src/keymap.c b/src/keymap.c
index cfc1e2e495c..510c5ea7f3e 100644
--- a/src/keymap.c
+++ b/src/keymap.c
@@ -2010,9 +2010,7 @@ then the value includes only maps for prefixes that start with PREFIX.  */)
         return Qnil;
     }
   else
-    maps = Fcons (Fcons (Fmake_vector (make_number (0), Qnil),
-                         get_keymap (keymap, 1, 0)),
-                  Qnil);
+    maps = Fcons (Fcons (zero_vector, get_keymap (keymap, 1, 0)), Qnil);
 
   /* For each map in the list maps,
      look at any other maps it points to,
diff --git a/src/lisp.h b/src/lisp.h
index 529feb99fd5..0bfe3c78118 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2605,6 +2605,7 @@ extern void mark_object (Lisp_Object);
 extern void refill_memory_reserve (void);
 #endif
 extern const char *pending_malloc_warning;
+extern Lisp_Object zero_vector;
 extern Lisp_Object *stack_base;
 extern Lisp_Object list1 (Lisp_Object);
 extern Lisp_Object list2 (Lisp_Object, Lisp_Object);