nostrdb

an unfairly fast embedded nostr database backed by lmdb
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check_type.h (2503B)


      1 /* CC0 (Public domain) - see LICENSE file for details */
      2 #ifndef CCAN_CHECK_TYPE_H
      3 #define CCAN_CHECK_TYPE_H
      4 #include "../config.h"
      5 
      6 /**
      7  * check_type - issue a warning or build failure if type is not correct.
      8  * @expr: the expression whose type we should check (not evaluated).
      9  * @type: the exact type we expect the expression to be.
     10  *
     11  * This macro is usually used within other macros to try to ensure that a macro
     12  * argument is of the expected type.  No type promotion of the expression is
     13  * done: an unsigned int is not the same as an int!
     14  *
     15  * check_type() always evaluates to 0.
     16  *
     17  * If your compiler does not support typeof, then the best we can do is fail
     18  * to compile if the sizes of the types are unequal (a less complete check).
     19  *
     20  * Example:
     21  *    // They should always pass a 64-bit value to _set_some_value!
     22  *    #define set_some_value(expr)            \
     23  *        _set_some_value((check_type((expr), uint64_t), (expr)))
     24  */
     25 
     26 /**
     27  * check_types_match - issue a warning or build failure if types are not same.
     28  * @expr1: the first expression (not evaluated).
     29  * @expr2: the second expression (not evaluated).
     30  *
     31  * This macro is usually used within other macros to try to ensure that
     32  * arguments are of identical types.  No type promotion of the expressions is
     33  * done: an unsigned int is not the same as an int!
     34  *
     35  * check_types_match() always evaluates to 0.
     36  *
     37  * If your compiler does not support typeof, then the best we can do is fail
     38  * to compile if the sizes of the types are unequal (a less complete check).
     39  *
     40  * Example:
     41  *    // Do subtraction to get to enclosing type, but make sure that
     42  *    // pointer is of correct type for that member.
     43  *    #define container_of(mbr_ptr, encl_type, mbr)            \
     44  *        (check_types_match((mbr_ptr), &((encl_type *)0)->mbr),    \
     45  *         ((encl_type *)                        \
     46  *          ((char *)(mbr_ptr) - offsetof(encl_type, mbr))))
     47  */
     48 #if HAVE_TYPEOF
     49 #define check_type(expr, type)            \
     50     ((typeof(expr) *)0 != (type *)0)
     51 
     52 #define check_types_match(expr1, expr2)        \
     53     ((typeof(expr1) *)0 != (typeof(expr2) *)0)
     54 #else
     55 #include <ccan/build_assert/build_assert.h>
     56 /* Without typeof, we can only test the sizes. */
     57 #define check_type(expr, type)                    \
     58     BUILD_ASSERT_OR_ZERO(sizeof(expr) == sizeof(type))
     59 
     60 #define check_types_match(expr1, expr2)                \
     61     BUILD_ASSERT_OR_ZERO(sizeof(expr1) == sizeof(expr2))
     62 #endif /* HAVE_TYPEOF */
     63 
     64 #endif /* CCAN_CHECK_TYPE_H */