typesafe_cb, hashtable: revise typesafe_cb arg order, neaten.

[ccan] / ccan / typesafe_cb / typesafe_cb.h

diff --git a/ccan/typesafe_cb/typesafe_cb.h b/ccan/typesafe_cb/typesafe_cb.h
index 0eb57d9524b2771e7cf3b43ba089e91fbd8c5992..02b4d72317031ecf223bc80aaeaa2948e20fdeaa 100644 (file)
--- a/ccan/typesafe_cb/typesafe_cb.h
+++ b/ccan/typesafe_cb/typesafe_cb.h
@@ -5,9 +5,9 @@
 #if HAVE_TYPEOF && HAVE_BUILTIN_CHOOSE_EXPR && HAVE_BUILTIN_TYPES_COMPATIBLE_P
 /**
  * cast_if_type - only cast an expression if it is of a given type
+ * @desttype: the type to cast to
  * @expr: the expression to cast
  * @oktype: the type we allow
- * @desttype: the type to cast to
  *
  * This macro is used to create functions which allow multiple types.
  * The result of this macro is used somewhere that a @desttype type is
@@ -27,15 +27,41 @@
  *     // We can take either an unsigned long or a void *.
  *     void _set_some_value(void *val);
  *     #define set_some_value(expr)                    \
- *             _set_some_value(cast_if_type((expr), unsigned long, void *))
+ *             _set_some_value(cast_if_type(void *, (expr), unsigned long))
  */
-#define cast_if_type(expr, oktype, desttype)                           \
+#define cast_if_type(desttype, expr, oktype)                           \
 __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype), \
                        (desttype)(expr), (expr))
 #else
 #define cast_if_type(expr, oktype, desttype) ((desttype)(expr))
 #endif
 
+/**
+ * cast_if_any - only cast an expression if it is one of the three given types
+ * @desttype: the type to cast to
+ * @expr: the expression to cast
+ * @ok1: the first type we allow
+ * @ok2: the second type we allow
+ * @ok3: the third type we allow
+ *
+ * This is a convenient wrapper for multiple cast_if_type() calls.  You can
+ * chain them inside each other (ie. use cast_if_any() for expr) if you need
+ * more than 3 arguments.
+ *
+ * Example:
+ *     // We can take either a long, unsigned long, void * or a const void *.
+ *     void _set_some_value(void *val);
+ *     #define set_some_value(expr)                                    \
+ *             _set_some_value(cast_if_any(void *, (expr),             \
+ *                                         long, unsigned long, const void *))
+ */
+#define cast_if_any(desttype, expr, ok1, ok2, ok3)                     \
+       cast_if_type(desttype,                                          \
+                    cast_if_type(desttype,                             \
+                                 cast_if_type(desttype, (expr), ok1),  \
+                                 ok2),                                 \
+                    ok3)
+
 /**
  * typesafe_cb - cast a callback function if it matches the arg
  * @rtype: the return type of the callback function
@@ -54,14 +80,11 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
  *     #define register_callback(fn, arg) \
  *             _register_callback(typesafe_cb(void, (fn), (arg)), (arg))
  */
-#define typesafe_cb(rtype, fn, arg)                                    \
-       cast_if_type(cast_if_type(cast_if_type((fn),                    \
-                                              rtype (*)(const typeof(*arg)*), \
-                                              rtype (*)(void *)),      \
-                                 rtype (*)(volatile typeof(*arg) *),   \
-                                 rtype (*)(void *)),                   \
-                    rtype (*)(typeof(arg)),                            \
-                    rtype (*)(void *))
+#define typesafe_cb(rtype, fn, arg)                    \
+       cast_if_any(rtype (*)(void *), (fn),            \
+                   rtype (*)(typeof(*arg)*),           \
+                   rtype (*)(const typeof(*arg)*),     \
+                   rtype (*)(volatile typeof(*arg)*))
 
 /**
  * typesafe_cb_const - cast a const callback function if it matches the arg
@@ -82,8 +105,8 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
  *             _register_callback(typesafe_cb_const(void, (fn), (arg)), (arg))
  */
 #define typesafe_cb_const(rtype, fn, arg)                              \
-       cast_if_type((fn),                                              \
-                    rtype (*)(const typeof(*arg)*), rtype (*)(const void *))
+       cast_if_type(rtype (*)(const void *), (fn),                     \
+                    rtype (*)(const typeof(*arg)*))
 
 /**
  * typesafe_cb_preargs - cast a callback function if it matches the arg
@@ -101,16 +124,10 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
  *                                (arg))
  */
 #define typesafe_cb_preargs(rtype, fn, arg, ...)                       \
-       cast_if_type(cast_if_type(cast_if_type((fn),                    \
-                                              rtype (*)(__VA_ARGS__,   \
-                                                        const typeof(*arg) *),\
-                                              rtype (*)(__VA_ARGS__,   \
-                                                        void *)),      \
-                                 rtype (*)(__VA_ARGS__,                \
-                                           volatile typeof(*arg) *),   \
-                                 rtype (*)(__VA_ARGS__, void *)),      \
-                    rtype (*)(__VA_ARGS__, typeof(arg)),               \
-                    rtype (*)(__VA_ARGS__, void *))
+       cast_if_any(rtype (*)(__VA_ARGS__, void *), (fn),               \
+                   rtype (*)(__VA_ARGS__, typeof(arg)),                \
+                   rtype (*)(__VA_ARGS__, const typeof(*arg) *),       \
+                   rtype (*)(__VA_ARGS__, volatile typeof(*arg) *))
 
 /**
  * typesafe_cb_postargs - cast a callback function if it matches the arg
@@ -124,20 +141,14 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
  * Example:
  *     void _register_callback(void (*fn)(void *arg, int), void *arg);
  *     #define register_callback(fn, arg) \
- *             _register_callback(typesafe_cb_preargs(void, (fn), (arg), int),\
+ *             _register_callback(typesafe_cb_postargs(void, (fn), (arg), int),\
  *                                (arg))
  */
 #define typesafe_cb_postargs(rtype, fn, arg, ...)                      \
-       cast_if_type(cast_if_type(cast_if_type((fn),                    \
-                                              rtype (*)(const typeof(*arg) *, \
-                                                        __VA_ARGS__),  \
-                                              rtype (*)(void *,        \
-                                                        __VA_ARGS__)), \
-                                 rtype (*)(volatile typeof(*arg) *,    \
-                                           __VA_ARGS__),               \
-                                 rtype (*)(void *, __VA_ARGS__)),      \
-                    rtype (*)(typeof(arg), __VA_ARGS__),               \
-                    rtype (*)(void *, __VA_ARGS__))
+       cast_if_any(rtype (*)(void *, __VA_ARGS__), (fn),               \
+                   rtype (*)(typeof(arg), __VA_ARGS__),                \
+                   rtype (*)(const typeof(*arg) *, __VA_ARGS__),       \
+                   rtype (*)(volatile typeof(*arg) *, __VA_ARGS__))
 
 /**
  * typesafe_cb_cmp - cast a compare function if it matches the arg
@@ -160,7 +171,7 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
  *                       typesafe_cb_cmp(int, (cmpfn), (base)), (arg))
  */
 #define typesafe_cb_cmp(rtype, cmpfn, arg)                             \
-       cast_if_type((cmpfn),                                           \
-                    rtype (*)(const typeof(*arg)*, const typeof(*arg)*), \
-                    rtype (*)(const void *, const void *))
+       cast_if_type(rtype (*)(const void *, const void *), (cmpfn),    \
+                    rtype (*)(const typeof(*arg)*, const typeof(*arg)*))
+                    
 #endif /* CCAN_CAST_IF_TYPE_H */