X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftypesafe_cb%2Ftypesafe_cb.h;h=0eb57d9524b2771e7cf3b43ba089e91fbd8c5992;hp=cc4ea8adbb9fba319e9ac0d5e45d13ca7dae6456;hb=517114490e7153643b4c0a12c59a060568d7ae00;hpb=650c775ff00cccd03fc84e7789a03c51d9839004;ds=inline

diff --git a/ccan/typesafe_cb/typesafe_cb.h b/ccan/typesafe_cb/typesafe_cb.h
index cc4ea8ad..0eb57d95 100644
--- a/ccan/typesafe_cb/typesafe_cb.h
+++ b/ccan/typesafe_cb/typesafe_cb.h
@@ -38,7 +38,7 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
 
 /**
  * typesafe_cb - cast a callback function if it matches the arg
- * @rettype: the return type of the callback function
+ * @rtype: the return type of the callback function
  * @fn: the callback function to cast
  * @arg: the (pointer) argument to hand to the callback function.
  *
@@ -54,18 +54,40 @@ __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(rettype, fn, arg)					\
+#define typesafe_cb(rtype, fn, arg)					\
 	cast_if_type(cast_if_type(cast_if_type((fn),			\
-					       rettype (*)(const typeof(arg)), \
-					       rettype (*)(void *)),	\
-				  rettype (*)(volatile typeof(arg)),	\
-				  rettype (*)(void *)),			\
-		     rettype (*)(typeof(arg)),				\
-		     rettype (*)(void *))
+					       rtype (*)(const typeof(*arg)*), \
+					       rtype (*)(void *)),	\
+				  rtype (*)(volatile typeof(*arg) *),	\
+				  rtype (*)(void *)),			\
+		     rtype (*)(typeof(arg)),				\
+		     rtype (*)(void *))
+
+/**
+ * typesafe_cb_const - cast a const callback function if it matches the 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.
+ *
+ * If a callback function takes a single argument, this macro does appropriate
+ * casts to a function which takes a single const void * argument if the
+ * callback provided matches the @arg.
+ *
+ * It is assumed that @arg is of pointer type: usually @arg is passed
+ * or assigned to a void * elsewhere anyway.
+ *
+ * Example:
+ *	void _register_callback(void (*fn)(const void *arg), const void *arg);
+ *	#define register_callback(fn, arg) \
+ *		_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 *))
 
 /**
  * typesafe_cb_preargs - cast a callback function if it matches the arg
- * @rettype: the return type of the callback function
+ * @rtype: the return type of the callback function
  * @fn: the callback function to cast
  * @arg: the (pointer) argument to hand to the callback function.
  *
@@ -78,21 +100,21 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
  *		_register_callback(typesafe_cb_preargs(void, (fn), (arg), int),\
  *				   (arg))
  */
-#define typesafe_cb_preargs(rettype, fn, arg, ...)			\
+#define typesafe_cb_preargs(rtype, fn, arg, ...)			\
 	cast_if_type(cast_if_type(cast_if_type((fn),			\
-					       rettype (*)(__VA_ARGS__,	\
-							   const typeof(arg)), \
-					       rettype (*)(__VA_ARGS__,	\
-							   void *)),	\
-				  rettype (*)(__VA_ARGS__,		\
-					      volatile typeof(arg)),	\
-				  rettype (*)(__VA_ARGS__, void *)),	\
-		     rettype (*)(__VA_ARGS__, typeof(arg)),		\
-		     rettype (*)(__VA_ARGS__, void *))
+					       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 *))
 
 /**
  * typesafe_cb_postargs - cast a callback function if it matches the arg
- * @rettype: the return type of the callback function
+ * @rtype: the return type of the callback function
  * @fn: the callback function to cast
  * @arg: the (pointer) argument to hand to the callback function.
  *
@@ -105,16 +127,40 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
  *		_register_callback(typesafe_cb_preargs(void, (fn), (arg), int),\
  *				   (arg))
  */
-#define typesafe_cb_postargs(rettype, fn, arg, ...)			\
+#define typesafe_cb_postargs(rtype, fn, arg, ...)			\
 	cast_if_type(cast_if_type(cast_if_type((fn),			\
-					       rettype (*)(const typeof(arg), \
-							   __VA_ARGS__), \
-					       rettype (*)(void *,	\
-							   __VA_ARGS__)), \
-				  rettype (*)(volatile typeof(arg),	\
-					      __VA_ARGS__),		\
-				  rettype (*)(void *, __VA_ARGS__)),	\
-		     rettype (*)(typeof(arg), __VA_ARGS__),		\
-		     rettype (*)(void *, __VA_ARGS__))
+					       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__))
 
+/**
+ * typesafe_cb_cmp - cast a compare function if it matches the arg
+ * @rtype: the return type of the callback function
+ * @fn: the callback function to cast
+ * @arg: the (pointer) argument(s) to hand to the compare function.
+ *
+ * If a callback function takes two matching-type arguments, this macro does
+ * appropriate casts to a function which takes two const void * arguments if
+ * the callback provided takes two a const pointers to @arg.
+ *
+ * It is assumed that @arg is of pointer type: usually @arg is passed
+ * or assigned to a void * elsewhere anyway.
+ *
+ * Example:
+ *	void _my_qsort(void *base, size_t nmemb, size_t size,
+ *		       int (*cmp)(const void *, const void *));
+ *	#define my_qsort(base, nmemb, cmpfn) \
+ *		_my_qsort((base), (nmemb), sizeof(*(base)), \
+ *			  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 *))
 #endif /* CCAN_CAST_IF_TYPE_H */