tdb2: suppress failtest more than once on mmap.
[ccan] / ccan / typesafe_cb / typesafe_cb.h
index cc4ea8adbb9fba319e9ac0d5e45d13ca7dae6456..884314975eda5506f6eed3ef941ae7401dd21a3e 100644 (file)
@@ -1,50 +1,79 @@
-#ifndef CCAN_CAST_IF_TYPE_H
-#define CCAN_CAST_IF_TYPE_H
+/* Licensed under LGPLv2.1+ - see LICENSE file for details */
+#ifndef CCAN_TYPESAFE_CB_H
+#define CCAN_TYPESAFE_CB_H
 #include "config.h"
 
 #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
- * @expr: the expression to cast
- * @oktype: the type we allow
+ * typesafe_cb_cast - only cast an expression if it matches a given type
  * @desttype: the type to cast to
+ * @oktype: the type we allow
+ * @expr: the expression to cast
  *
  * 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 @expr is exactly of type @oktype, then it will be
+ * cast to @desttype type, otherwise left alone.
  *
  * This macro can be used in static initializers.
  *
  * This is merely useful for warnings: if the compiler does not
- * support the primitives required for cast_if_type(), it becomes an
+ * support the primitives required for typesafe_cb_cast(), it becomes an
  * unconditional cast, and the @oktype argument is not used.  In
- * particular, this means that @oktype can be a type which uses
- * the "typeof": it will not be evaluated if typeof is not supported.
+ * particular, this means that @oktype can be a type which uses the
+ * "typeof": it will not be evaluated if typeof is not supported.
  *
  * Example:
  *     // 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 *))
+ *     #define set_some_value(e)                       \
+ *             _set_some_value(typesafe_cb_cast(void *, (e), unsigned long))
  */
-#define cast_if_type(expr, oktype, desttype)                           \
-__builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype), \
-                       (desttype)(expr), (expr))
+#define typesafe_cb_cast(desttype, oktype, expr)                       \
+       __builtin_choose_expr(                                          \
+               __builtin_types_compatible_p(__typeof__(0?(expr):(expr)), \
+                                            oktype),                   \
+               (desttype)(expr), (expr))
 #else
-#define cast_if_type(expr, oktype, desttype) ((desttype)(expr))
+#define typesafe_cb_cast(desttype, oktype, expr) ((desttype)(expr))
 #endif
 
+/**
+ * typesafe_cb_cast3 - only cast an expression if it matches given types
+ * @desttype: the type to cast to
+ * @ok1: the first type we allow
+ * @ok2: the second type we allow
+ * @ok3: the third type we allow
+ * @expr: the expression to cast
+ *
+ * This is a convenient wrapper for multiple typesafe_cb_cast() calls.
+ * You can chain them inside each other (ie. use typesafe_cb_cast()
+ * 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(typesafe_cb_cast3(void *,,              \
+ *                                         long, unsigned long, const void *,\
+ *                                         (expr)))
+ */
+#define typesafe_cb_cast3(desttype, ok1, ok2, ok3, expr)               \
+       typesafe_cb_cast(desttype, ok1,                                 \
+                        typesafe_cb_cast(desttype, ok2,                \
+                                         typesafe_cb_cast(desttype, ok3, \
+                                                          (expr))))
+
 /**
  * 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
+ * @atype: the (pointer) type which the callback function expects.
  * @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 void * argument if the
- * callback provided matches the @arg (or a const or volatile version).
+ * appropriate casts to a function which takes a single atype 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.
@@ -52,20 +81,17 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
  * Example:
  *     void _register_callback(void (*fn)(void *arg), void *arg);
  *     #define register_callback(fn, arg) \
- *             _register_callback(typesafe_cb(void, (fn), (arg)), (arg))
+ *             _register_callback(typesafe_cb(void, (fn), void*, (arg)), (arg))
  */
-#define typesafe_cb(rettype, 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 *))
+#define typesafe_cb(rtype, atype, fn, arg)                     \
+       typesafe_cb_cast(rtype (*)(atype),                      \
+                        rtype (*)(__typeof__(arg)),            \
+                        (fn))
 
 /**
  * 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
+ * @atype: the (pointer) type which the callback function expects.
  * @fn: the callback function to cast
  * @arg: the (pointer) argument to hand to the callback function.
  *
@@ -74,25 +100,20 @@ __builtin_choose_expr(__builtin_types_compatible_p(typeof(1?(expr):0), oktype),
  *
  * Example:
  *     void _register_callback(void (*fn)(int, void *arg), void *arg);
- *     #define register_callback(fn, arg) \
- *             _register_callback(typesafe_cb_preargs(void, (fn), (arg), int),\
+ *     #define register_callback(fn, arg)                                 \
+ *             _register_callback(typesafe_cb_preargs(void, void *,       \
+ *                                (fn), (arg), int),                      \
  *                                (arg))
  */
-#define typesafe_cb_preargs(rettype, 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 *))
+#define typesafe_cb_preargs(rtype, atype, fn, arg, ...)                        \
+       typesafe_cb_cast(rtype (*)(__VA_ARGS__, atype),                 \
+                        rtype (*)(__VA_ARGS__, __typeof__(arg)),       \
+                        (fn))
 
 /**
  * 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
+ * @atype: the (pointer) type which the callback function expects.
  * @fn: the callback function to cast
  * @arg: the (pointer) argument to hand to the callback function.
  *
@@ -102,19 +123,12 @@ __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), void *, \
+ *                                (arg), int),                             \
  *                                (arg))
  */
-#define typesafe_cb_postargs(rettype, 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__))
-
+#define typesafe_cb_postargs(rtype, atype, fn, arg, ...)               \
+       typesafe_cb_cast(rtype (*)(atype, __VA_ARGS__),                 \
+                        rtype (*)(__typeof__(arg), __VA_ARGS__),       \
+                        (fn))
 #endif /* CCAN_CAST_IF_TYPE_H */