Add helper 'for_each_dive()' dive iterator

It's an easy thing to do, but the for-loop ends up being pretty ugly, so
hide it behind the macro.

It would be even prettier with one of the (few) useful C99 features:
local for-loop variables.  However, gcc needs special command line
options, and other compilers may not do it at all. So instead of doing

   #define for_each_dive(_x) \
      for (int _i = 0; ((_x) = get_dive(_i)) != NULL; _i++)

we require that the user declare the index iterator too, and the use
syntax becomes

   for_each_dive(idx, dive) {
	... use idx/dive here ...
   }

And hey, maybe somebody actually will want to use the index, so maybe
that's not all bad.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/dive.h b/dive.h
index 7ceab643a..ab854e37e 100644
--- a/dive.h
+++ b/dive.h
@@ -295,6 +295,16 @@ static inline struct dive *get_dive(unsigned int nr)
 	return dive_table.dives[nr];
 }
 
+/*
+ * Iterate over each dive, with the first parameter being the index
+ * iterator variable, and the second one being the dive one.
+ *
+ * I don't think anybody really wants the index, and we could make
+ * it local to the for-loop, but that would make us requires C99.
+ */
+#define for_each_dive(_i,_x) \
+	for ((_i) = 0; ((_x) = get_dive(_i)) != NULL; (_i)++)
+
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