-#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.
* 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.
*
*
* 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.
*
* 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 */
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