X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftypesafe_cb%2Ftypesafe_cb.h;h=02b4d72317031ecf223bc80aaeaa2948e20fdeaa;hp=0eb57d9524b2771e7cf3b43ba089e91fbd8c5992;hb=b1c867121f379d76dc7fb7d99bae77e2b7d99841;hpb=184070eb4a4a2e130c0053eb82fd8c96a19e954f diff --git a/ccan/typesafe_cb/typesafe_cb.h b/ccan/typesafe_cb/typesafe_cb.h index 0eb57d95..02b4d723 100644 --- 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 */