master 37889523278: Add new `swap` macro and use it

[Stefan Kangas]

branch: master
commit 37889523278fe65733938fb11c3701898309961c
Author: Stefan Kangas <stefankangas@gmail.com>
Commit: Stefan Kangas <stefankangas@gmail.com>

    Add new `swap` macro and use it
    
    A `swap` macro prevents programming errors and is more concise.
    It is a natural addition to our existing `min` and `max` macros.
    
    * src/lisp.h (swap): New macro.
    * lwlib/xlwmenu.c (draw_shadow_rectangle, draw_shadow_rhombus):
    * src/androidterm.c (android_get_surrounding_text):
    * src/buffer.c (Fmake_overlay, modify_overlay, Fmove_overlay):
    * src/dispnew.c (swap_glyphs_in_rows, reverse_rows):
    * src/editfns.c (Finsert_buffer_substring)
    (Fcompare_buffer_substrings):
    * src/eval.c (run_hook_wrapped_funcall):
    * src/fns.c (extract_data_from_object):
    * src/regex-emacs.c (forall_firstchar_1):
    * src/textconv.c (textconv_query, get_extracted_text)
    (get_surrounding_text):
    * src/textprop.c (validate_interval_range)
    (verify_interval_modification):
    * src/w32uniscribe.c (OTF_INT16_VAL):
    * src/xfaces.c (load_face_colors):
    * src/xterm.c (SWAPCARD32): Prefer using above macro to open-coding.
---
 lwlib/xlwmenu.c    | 14 ++------------
 src/androidterm.c  |  7 +------
 src/buffer.c       | 16 +++-------------
 src/dispnew.c      | 20 +++-----------------
 src/editfns.c      | 10 +++++-----
 src/eval.c         |  9 +++------
 src/fns.c          |  6 +-----
 src/lisp.h         |  4 ++++
 src/regex-emacs.c  |  4 ++--
 src/textconv.c     | 28 +++++++---------------------
 src/textprop.c     | 13 ++-----------
 src/w32uniscribe.c |  4 ++--
 src/xfaces.c       |  7 +------
 src/xterm.c        | 10 +++++-----
 14 files changed, 41 insertions(+), 111 deletions(-)

diff --git a/lwlib/xlwmenu.c b/lwlib/xlwmenu.c
index 0f8f94b803c..a3d9474bed0 100644
--- a/lwlib/xlwmenu.c
+++ b/lwlib/xlwmenu.c
@@ -671,12 +671,7 @@ draw_shadow_rectangle (XlwMenuWidget mw, Window window, 
int x, int y,
     }
 
   if (!erase_p && down_p)
-    {
-      GC temp;
-      temp = top_gc;
-      top_gc = bottom_gc;
-      bottom_gc = temp;
-    }
+    swap (top_gc, bottom_gc);
 
   /* Do draw (or erase) shadows */
   points [0].x = x;
@@ -757,12 +752,7 @@ draw_shadow_rhombus (XlwMenuWidget mw, Window window, int 
x, int y,
     }
 
   if (!erase_p && down_p)
-    {
-      GC temp;
-      temp = top_gc;
-      top_gc = bottom_gc;
-      bottom_gc = temp;
-    }
+    swap (top_gc, bottom_gc);
 
   points [0].x = x;
   points [0].y = y + height / 2;
diff --git a/src/androidterm.c b/src/androidterm.c
index 2e4ee64f390..34734e63c37 100644
--- a/src/androidterm.c
+++ b/src/androidterm.c
@@ -5849,7 +5849,6 @@ android_get_surrounding_text (void *data)
 {
   struct android_get_surrounding_text_context *request;
   struct frame *f;
-  ptrdiff_t temp;
 
   request = data;
 
@@ -5870,11 +5869,7 @@ android_get_surrounding_text (void *data)
      bad input methods.  */
 
   if (request->end < request->start)
-    {
-      temp = request->start;
-      request->start = request->end;
-      request->end = temp;
-    }
+    swap (request->start, request->end);
 
   /* Retrieve the conversion region.  */
 
diff --git a/src/buffer.c b/src/buffer.c
index 352aca8ddfd..14c67224551 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -3591,10 +3591,7 @@ for the rear of the overlay advance when text is 
inserted there
   CHECK_FIXNUM_COERCE_MARKER (end);
 
   if (XFIXNUM (beg) > XFIXNUM (end))
-    {
-      Lisp_Object temp;
-      temp = beg; beg = end; end = temp;
-    }
+    swap (beg, end);
 
   ptrdiff_t obeg = clip_to_bounds (BUF_BEG (b), XFIXNUM (beg), BUF_Z (b));
   ptrdiff_t oend = clip_to_bounds (obeg, XFIXNUM (end), BUF_Z (b));
@@ -3614,11 +3611,7 @@ static void
 modify_overlay (struct buffer *buf, ptrdiff_t start, ptrdiff_t end)
 {
   if (start > end)
-    {
-      ptrdiff_t temp = start;
-      start = end;
-      end = temp;
-    }
+    swap (start, end);
 
   BUF_COMPUTE_UNCHANGED (buf, start, end);
 
@@ -3658,10 +3651,7 @@ buffer.  */)
   CHECK_FIXNUM_COERCE_MARKER (end);
 
   if (XFIXNUM (beg) > XFIXNUM (end))
-    {
-      Lisp_Object temp;
-      temp = beg; beg = end; end = temp;
-    }
+    swap (beg, end);
 
   specbind (Qinhibit_quit, Qt); /* FIXME: Why?  */
 
diff --git a/src/dispnew.c b/src/dispnew.c
index d0f259eef6c..78ec3537a35 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -649,14 +649,7 @@ reverse_rows (struct glyph_matrix *matrix, int start, int 
end)
   int i, j;
 
   for (i = start, j = end - 1; i < j; ++i, --j)
-    {
-      /* Non-ISO HP/UX compiler doesn't like auto struct
-        initialization.  */
-      struct glyph_row temp;
-      temp = matrix->rows[i];
-      matrix->rows[i] = matrix->rows[j];
-      matrix->rows[j] = temp;
-    }
+    swap (matrix->rows[i], matrix->rows[j]);
 }
 
 
@@ -966,9 +959,7 @@ increment_row_positions (struct glyph_row *row,
 static void
 swap_glyphs_in_rows (struct glyph_row *a, struct glyph_row *b)
 {
-  int area;
-
-  for (area = 0; area < LAST_AREA; ++area)
+  for (int area = 0; area < LAST_AREA; ++area)
     {
       /* Number of glyphs to swap.  */
       int max_used = max (a->used[area], b->used[area]);
@@ -984,12 +975,7 @@ swap_glyphs_in_rows (struct glyph_row *a, struct glyph_row 
*b)
 
       while (glyph_a < glyph_a_end)
        {
-         /* Non-ISO HP/UX compiler doesn't like auto struct
-             initialization.  */
-         struct glyph temp;
-         temp = *glyph_a;
-         *glyph_a = *glyph_b;
-         *glyph_b = temp;
+         swap (*glyph_a, *glyph_b);
          ++glyph_a;
          ++glyph_b;
        }
diff --git a/src/editfns.c b/src/editfns.c
index f3b3cfb7243..2e455a2efed 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -1739,7 +1739,7 @@ versa, strings are converted from unibyte to multibyte or 
vice versa
 using `string-make-multibyte' or `string-make-unibyte', which see.  */)
   (Lisp_Object buffer, Lisp_Object start, Lisp_Object end)
 {
-  register EMACS_INT b, e, temp;
+  register EMACS_INT b, e;
   register struct buffer *bp, *obuf;
   Lisp_Object buf;
 
@@ -1753,7 +1753,7 @@ using `string-make-multibyte' or `string-make-unibyte', 
which see.  */)
   b = !NILP (start) ? fix_position (start) : BUF_BEGV (bp);
   e = !NILP (end) ? fix_position (end) : BUF_ZV (bp);
   if (b > e)
-    temp = b, b = e, e = temp;
+    swap (b, e);
 
   if (!(BUF_BEGV (bp) <= b && e <= BUF_ZV (bp)))
     args_out_of_range (start, end);
@@ -1782,7 +1782,7 @@ The value of `case-fold-search' in the current buffer
 determines whether case is significant or ignored.  */)
   (Lisp_Object buffer1, Lisp_Object start1, Lisp_Object end1, Lisp_Object 
buffer2, Lisp_Object start2, Lisp_Object end2)
 {
-  register EMACS_INT begp1, endp1, begp2, endp2, temp;
+  register EMACS_INT begp1, endp1, begp2, endp2;
   register struct buffer *bp1, *bp2;
   register Lisp_Object trt
     = (!NILP (Vcase_fold_search)
@@ -1808,7 +1808,7 @@ determines whether case is significant or ignored.  */)
   begp1 = !NILP (start1) ? fix_position (start1) : BUF_BEGV (bp1);
   endp1 = !NILP (end1) ? fix_position (end1) : BUF_ZV (bp1);
   if (begp1 > endp1)
-    temp = begp1, begp1 = endp1, endp1 = temp;
+    swap (begp1, endp1);
 
   if (!(BUF_BEGV (bp1) <= begp1
        && begp1 <= endp1
@@ -1833,7 +1833,7 @@ determines whether case is significant or ignored.  */)
   begp2 = !NILP (start2) ? fix_position (start2) : BUF_BEGV (bp2);
   endp2 = !NILP (end2) ? fix_position (end2) : BUF_ZV (bp2);
   if (begp2 > endp2)
-    temp = begp2, begp2 = endp2, endp2 = temp;
+    swap (begp2, endp2);
 
   if (!(BUF_BEGV (bp2) <= begp2
        && begp2 <= endp2
diff --git a/src/eval.c b/src/eval.c
index 94f6d8e31f8..6a866d6cc32 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2794,12 +2794,9 @@ usage: (run-hook-with-args-until-failure HOOK &rest 
ARGS)  */)
 static Lisp_Object
 run_hook_wrapped_funcall (ptrdiff_t nargs, Lisp_Object *args)
 {
-  Lisp_Object tmp = args[0], ret;
-  args[0] = args[1];
-  args[1] = tmp;
-  ret = Ffuncall (nargs, args);
-  args[1] = args[0];
-  args[0] = tmp;
+  swap (args[0], args[1]);
+  Lisp_Object ret = Ffuncall (nargs, args);
+  swap (args[1], args[0]);
   return ret;
 }
 
diff --git a/src/fns.c b/src/fns.c
index c03aea02397..c8adc5cb891 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -5674,11 +5674,7 @@ extract_data_from_object (Lisp_Object spec,
       b = !NILP (start) ? fix_position (start) : BEGV;
       e = !NILP (end) ? fix_position (end) : ZV;
       if (b > e)
-       {
-         EMACS_INT temp = b;
-         b = e;
-         e = temp;
-       }
+       swap (b, e);
 
       if (!(BEGV <= b && e <= ZV))
        args_out_of_range (start, end);
diff --git a/src/lisp.h b/src/lisp.h
index 44f69892c6f..f96932ab0c1 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -67,6 +67,10 @@ INLINE_HEADER_BEGIN
 #define max(a, b) ((a) > (b) ? (a) : (b))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
+/* Swap values of a and b.  */
+#define swap(a, b) \
+  do { typeof (a) __tmp; __tmp = (a); (a) = (b); (b) = __tmp; } while (0);
+
 /* Number of elements in an array.  */
 #define ARRAYELTS(arr) (sizeof (arr) / sizeof (arr)[0])
 
diff --git a/src/regex-emacs.c b/src/regex-emacs.c
index 6aa6f4f9b34..fdc2cc63445 100644
--- a/src/regex-emacs.c
+++ b/src/regex-emacs.c
@@ -2839,7 +2839,7 @@ forall_firstchar_1 (re_char *p, re_char *pend,
 
   while (true)
     {
-      re_char *newp1, *newp2, *tmp;
+      re_char *newp1, *newp2;
       re_char *p_orig = p;
       int offset;
 
@@ -2930,7 +2930,7 @@ forall_firstchar_1 (re_char *p, re_char *pend,
            /* We have to check that both destinations are safe.
               Arrange for `newp1` to be the smaller of the two.  */
            if (newp1 > newp2)
-             (tmp = newp1, newp1 = newp2, newp2 = tmp);
+             swap (newp1, newp2);
 
            if (newp2 <= p_orig) /* Both destinations go backward!  */
              {
diff --git a/src/textconv.c b/src/textconv.c
index 2a7b0ed330d..e0707522d7e 100644
--- a/src/textconv.c
+++ b/src/textconv.c
@@ -176,7 +176,7 @@ textconv_query (struct frame *f, struct 
textconv_callback_struct *query,
 {
   specpdl_ref count;
   ptrdiff_t pos, pos_byte, end, end_byte, start;
-  ptrdiff_t temp, temp1, mark;
+  ptrdiff_t mark;
   char *buffer;
   struct window *w;
 
@@ -383,12 +383,8 @@ textconv_query (struct frame *f, struct 
textconv_callback_struct *query,
   if (end < pos)
     {
       eassert (end_byte < pos_byte);
-      temp = pos_byte;
-      temp1 = pos;
-      pos_byte = end_byte;
-      pos = end;
-      end = temp1;
-      end_byte = temp;
+      swap (pos_byte, end_byte);
+      swap (pos, end);
     }
 
   /* Return the string first.  */
@@ -1905,15 +1901,9 @@ get_extracted_text (struct frame *f, ptrdiff_t n,
          start = marker_position (BVAR (current_buffer, mark));
          end = PT;
 
-         /* Sort start and end.  start_byte is used to hold a
-            temporary value.  */
-
+         /* Sort start and end.  */
          if (start > end)
-           {
-             start_byte = end;
-             end = start;
-             start = start_byte;
-           }
+           swap (start, end);
        }
       else
        goto finish;
@@ -1979,7 +1969,7 @@ get_surrounding_text (struct frame *f, ptrdiff_t left,
                      ptrdiff_t *end_return)
 {
   specpdl_ref count;
-  ptrdiff_t start, end, start_byte, end_byte, mark, temp;
+  ptrdiff_t start, end, start_byte, end_byte, mark;
   char *buffer;
 
   if (!WINDOW_LIVE_P (f->old_selected_window))
@@ -2012,11 +2002,7 @@ get_surrounding_text (struct frame *f, ptrdiff_t left,
   /* Now sort start and end.  */
 
   if (end < start)
-    {
-      temp = start;
-      start = end;
-      end = temp;
-    }
+    swap (start, end)
 
   /* And subtract left and right.  */
 
diff --git a/src/textprop.c b/src/textprop.c
index 7d9aae0d2c5..ec9435219ea 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -142,12 +142,7 @@ validate_interval_range (Lisp_Object object, Lisp_Object 
*begin,
     return NULL;
 
   if (XFIXNUM (*begin) > XFIXNUM (*end))
-    {
-      Lisp_Object n;
-      n = *begin;
-      *begin = *end;
-      *end = n;
-    }
+    swap (*begin, *end);
 
   if (BUFFERP (object))
     {
@@ -2201,11 +2196,7 @@ verify_interval_modification (struct buffer *buf,
     return;
 
   if (start > end)
-    {
-      ptrdiff_t temp = start;
-      start = end;
-      end = temp;
-    }
+    swap (start, end);
 
   /* For an insert operation, check the two chars around the position.  */
   if (start == end)
diff --git a/src/w32uniscribe.c b/src/w32uniscribe.c
index a73c0de06f9..c417159cf9e 100644
--- a/src/w32uniscribe.c
+++ b/src/w32uniscribe.c
@@ -765,10 +765,10 @@ add_opentype_font_name_to_list (ENUMLOGFONTEX 
*logical_font,
 
 #define OTF_INT16_VAL(TABLE, OFFSET, PTR)                   \
   do {                                                      \
-    BYTE temp, data[2];                                             \
+    BYTE data[2];                                           \
     if (GetFontData (context, TABLE, OFFSET, data, 2) != 2)  \
       goto font_table_error;                                \
-    temp = data[0], data[0] = data[1], data[1] = temp;      \
+    swap (data[0], data[1]);                                \
     memcpy (PTR, data, 2);                                  \
   } while (0)
 
diff --git a/src/xfaces.c b/src/xfaces.c
index e30c2fac70c..f79eb022e15 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -1357,12 +1357,7 @@ load_face_colors (struct frame *f, struct face *face,
 
   /* Swap colors if face is inverse-video.  */
   if (EQ (attrs[LFACE_INVERSE_INDEX], Qt))
-    {
-      Lisp_Object tmp;
-      tmp = fg;
-      fg = bg;
-      bg = tmp;
-    }
+    swap (fg, bg);
 
   /* Check for support for foreground, not for background because
      face_color_supported_p is smart enough to know that grays are
diff --git a/src/xterm.c b/src/xterm.c
index 1f398b2e39a..0b83b0554b3 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -1569,19 +1569,19 @@ typedef enum xm_byte_order
 #define SWAPCARD32(l)                          \
   {                                            \
     struct { unsigned t : 32; } bit32;         \
-    char n, *tp = (char *) &bit32;             \
+    char *tp = (char *) &bit32;                        \
     bit32.t = l;                               \
-    n = tp[0]; tp[0] = tp[3]; tp[3] = n;       \
-    n = tp[1]; tp[1] = tp[2]; tp[2] = n;       \
+    swap (tp[0], tp[3]);                       \
+    swap (tp[1], tp[2]);                       \
     l = bit32.t;                               \
   }
 
 #define SWAPCARD16(s)                          \
   {                                            \
     struct { unsigned t : 16; } bit16;         \
-    char n, *tp = (char *) &bit16;             \
+    char *tp = (char *) &bit16;                        \
     bit16.t = s;                               \
-    n = tp[0]; tp[0] = tp[1]; tp[1] = n;       \
+    swap (tp[0], tp[1]);                       \
     s = bit16.t;                               \
   }