macro: add a macro to test whether a value is in a specified list

Introduce IN_SET() macro to nicely check whether a value a is one of a
few listed values.

This makes writing this:

        if (a == 1 || a == 7 || a == 8 || a == 9)

nicer, by allowing this:

        if (IN_SET(a, 1, 7, 8, 9))

This is particularly useful for state machine enums.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/shared/macro.h b/src/shared/macro.h
index 9f5f51cb13..54b641be23 100644
--- a/src/shared/macro.h
+++ b/src/shared/macro.h
@@ -285,4 +285,17 @@ do {                                                                    \
 #define SET_FLAG(v, flag, b) \
         (v) = (b) ? ((v) | (flag)) : ((v) & ~(flag))
 
+#define IN_SET(x, ...) ({                                               \
+        typeof(x) _x = (x);                                             \
+        unsigned _i;                                                    \
+        bool _found = false;                                            \
+        for (_i = 0; _i < sizeof((typeof(_x)[]) { __VA_ARGS__ })/sizeof(typeof(_x)); _i++) \
+                if (((typeof(_x)[]) { __VA_ARGS__ })[_i] == _x) {       \
+                        _found = true;                                  \
+                        break;                                          \
+                }                                                       \
+        _found;                                                         \
+        })
+
+
 #include "log.h"