X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftypesafe_cb%2Ftypesafe_cb.h;h=7347b7b2912c20291bfbdd9adfdcbb430334c07c;hp=f5e416de2de26c0e65605c5ed923ce0177cf4c33;hb=a39bf3aca1b60365efaf8b1eeb2b2c58b09ffab6;hpb=67a035869c6f3512ba943ae197b407f182a4506d

diff --git a/ccan/typesafe_cb/typesafe_cb.h b/ccan/typesafe_cb/typesafe_cb.h
index f5e416de..7347b7b2 100644
--- a/ccan/typesafe_cb/typesafe_cb.h
+++ b/ccan/typesafe_cb/typesafe_cb.h
@@ -12,9 +12,8 @@
  *
  * This macro is used to create functions which allow multiple types.
  * The result of this macro is used somewhere that a @desttype type is
- * expected: if @expr was of type @oktype, it will be cast to
- * @desttype type.  As a result, if @expr is any type other than
- * @oktype or @desttype, a compiler warning will be issued.
+ * expected: if @test is exactly of type @oktype, then @expr will be
+ * cast to @desttype type, otherwise left alone.
  *
  * This macro can be used in static initializers.
  *
@@ -31,7 +30,7 @@
  *		_set_some_value(cast_if_type(void *, (e), (e), unsigned long))
  */
 #define cast_if_type(desttype, expr, test, oktype)			\
-__builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(test):0), oktype), \
+	__builtin_choose_expr(__builtin_types_compatible_p(typeof(test), oktype), \
 			(desttype)(expr), (expr))
 #else
 #define cast_if_type(desttype, expr, test, oktype) ((desttype)(expr))
@@ -61,7 +60,9 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(test):0), oktype),
 	cast_if_type(desttype,						\
 		     cast_if_type(desttype,				\
 				  cast_if_type(desttype, (expr), (test), ok1), \
+				  (test),				\
 				  ok2),					\
+		     (test),						\
 		     ok3)
 
 /**
@@ -77,6 +78,9 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(test):0), oktype),
  * It is assumed that @arg is of pointer type: usually @arg is passed
  * or assigned to a void * elsewhere anyway.
  *
+ * This will not work with a NULL @fn argument: see typesafe_cb_def or
+ * typesafe_cb_exact.
+ *
  * Example:
  *	void _register_callback(void (*fn)(void *arg), void *arg);
  *	#define register_callback(fn, arg) \
@@ -85,6 +89,46 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(test):0), oktype),
 #define typesafe_cb(rtype, fn, arg)			\
 	cast_if_type(rtype (*)(void *), (fn), (fn)(arg), rtype)
 
+/**
+ * typesafe_cb_def - cast a callback fn if it matches arg (of defined type)
+ * @rtype: the return type of the callback function
+ * @fn: the callback function to cast
+ * @arg: the (pointer) argument to hand to the callback function.
+ *
+ * This is typesafe_cb(), except the type must be defined (eg. if it's
+ * struct foo *, the definition of struct foo must be visible).  For many
+ * applications, this is reasonable.
+ *
+ * This variant can accept @fn equal to NULL.
+ *
+ * Example:
+ *	void _register_callback(void (*fn)(void *arg), void *arg);
+ *	#define register_callback(fn, arg) \
+ *		_register_callback(typesafe_cb_def(void, (fn), (arg)), (arg))
+ */
+#define typesafe_cb_def(rtype, fn, arg)			\
+	cast_if_any(rtype (*)(void *), (fn), (fn)+0,	\
+		    rtype (*)(typeof(*arg)*),		\
+		    rtype (*)(const typeof(*arg)*),	\
+		    rtype (*)(volatile typeof(*arg)*))
+
+/**
+ * typesafe_cb_exact - cast a callback fn if it exactly matches arg
+ * @rtype: the return type of the callback function
+ * @fn: the callback function to cast
+ * @arg: the (pointer) argument to hand to the callback function.
+ *
+ * This is typesafe_cb(), except the @fn can be NULL, or must exactly match
+ * the @arg type (no const or volatile).
+ *
+ * Example:
+ *	void _register_callback(void (*fn)(void *arg), void *arg);
+ *	#define register_callback(fn, arg) \
+ *		_register_callback(typesafe_cb_exact(void, (fn), (arg)), (arg))
+ */
+#define typesafe_cb_exact(rtype, fn, arg)				\
+	cast_if_type(rtype (*)(void *), (fn), (fn)+0, rtype (*)(typeof(arg)))
+
 /**
  * typesafe_cb_const - cast a const callback function if it matches the arg
  * @rtype: the return type of the callback function
@@ -103,10 +147,8 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(test):0), oktype),
  *	#define register_callback(fn, arg) \
  *		_register_callback(typesafe_cb_const(void, (fn), (arg)), (arg))
  */
-#define typesafe_cb_const(rtype, fn, arg)				\
-	sizeof((fn)((const void *)0)),					\
-		cast_if_type(rtype (*)(const void *),			\
-			     (fn), (fn)(arg), rtype (*)(typeof(arg)))
+#define typesafe_cb_const(rtype, fn, arg)			\
+	cast_if_type(rtype (*)(const void *), (fn), (fn)(arg), rtype)
 
 /**
  * typesafe_cb_preargs - cast a callback function if it matches the arg
@@ -124,8 +166,9 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(test):0), oktype),
  *				   (arg))
  */
 #define typesafe_cb_preargs(rtype, fn, arg, ...)			\
-	cast_if_type(rtype (*)(__VA_ARGS__, void *), (fn), (fn),	\
+	cast_if_type(rtype (*)(__VA_ARGS__, void *), (fn), (fn)+0,	\
 		     rtype (*)(__VA_ARGS__, typeof(arg)))
+
 /**
  * typesafe_cb_postargs - cast a callback function if it matches the arg
  * @rtype: the return type of the callback function
@@ -142,8 +185,9 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(test):0), oktype),
  *				   (arg))
  */
 #define typesafe_cb_postargs(rtype, fn, arg, ...)			\
-	cast_if_type(rtype (*)(void *, __VA_ARGS__), (fn), (fn),	\
+	cast_if_type(rtype (*)(void *, __VA_ARGS__), (fn), (fn)+0,	\
 		     rtype (*)(typeof(arg), __VA_ARGS__))
+
 /**
  * typesafe_cb_cmp - cast a compare function if it matches the arg
  * @rtype: the return type of the callback function
@@ -166,7 +210,7 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(test):0), oktype),
  *			  typesafe_cb_cmp(int, (cmpfn), (base)), (arg))
  */
 #define typesafe_cb_cmp(rtype, cmpfn, arg)				\
-	cast_if_type(rtype (*)(const void *, const void *), (cmpfn),	\
+	cast_if_type(rtype (*)(const void *, const void *), (cmpfn), (cmpfn)+0, \
 		     rtype (*)(const typeof(*arg)*, const typeof(*arg)*))
 		     
 #endif /* CCAN_CAST_IF_TYPE_H */