X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftypesafe_cb%2Ftypesafe_cb.h;h=40cfa3979891c3ac04cac3a8204e8d59693d8e70;hp=0eb57d9524b2771e7cf3b43ba089e91fbd8c5992;hb=b0fa019adb998c20a8740f5696b61ae87d2a77a6;hpb=517114490e7153643b4c0a12c59a060568d7ae00;ds=inline diff --git a/ccan/typesafe_cb/typesafe_cb.h b/ccan/typesafe_cb/typesafe_cb.h index 0eb57d95..40cfa397 100644 --- a/ccan/typesafe_cb/typesafe_cb.h +++ b/ccan/typesafe_cb/typesafe_cb.h @@ -1,93 +1,96 @@ -#ifndef CCAN_CAST_IF_TYPE_H -#define CCAN_CAST_IF_TYPE_H +#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 - cast a 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 void * argument if the - * callback provided matches the @arg (or a const or volatile version). + * 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 * - * It is assumed that @arg is of pointer type: usually @arg is passed - * or assigned to a void * elsewhere anyway. + * 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: - * void _register_callback(void (*fn)(void *arg), void *arg); - * #define register_callback(fn, arg) \ - * _register_callback(typesafe_cb(void, (fn), (arg)), (arg)) + * // 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(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_cast3(desttype, ok1, ok2, ok3, expr) \ + typesafe_cb_cast(desttype, ok1, \ + typesafe_cb_cast(desttype, ok2, \ + typesafe_cb_cast(desttype, ok3, \ + (expr)))) /** - * typesafe_cb_const - cast a const callback function if it matches the arg + * typesafe_cb - cast a callback function if it matches the arg * @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 const void * argument if the + * If a callback function takes a single argument, this macro does + * 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)(const void *arg), const void *arg); + * void _register_callback(void (*fn)(void *arg), void *arg); * #define register_callback(fn, arg) \ - * _register_callback(typesafe_cb_const(void, (fn), (arg)), (arg)) + * _register_callback(typesafe_cb(void, (fn), void*, (arg)), (arg)) */ -#define typesafe_cb_const(rtype, fn, arg) \ - cast_if_type((fn), \ - rtype (*)(const typeof(*arg)*), rtype (*)(const 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 * @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. * @@ -96,25 +99,20 @@ __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, (fn), void *, \ + * (arg), int), \ * (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 *)) +#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 * @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. * @@ -124,43 +122,12 @@ __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(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__)) - -/** - * 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 *)) +#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 */