STINNER Victor <[email protected]> added the comment:
Modules/hashtable.c and Modules/hashtable.h use a different approach. The
variable size data is *not* part of the structure:
typedef struct {
/* used by _Py_hashtable_t.buckets to link entries */
_Py_slist_item_t _Py_slist_item;
Py_uhash_t key_hash;
/* key (key_size bytes) and then data (data_size bytes) follows */
} _Py_hashtable_entry_t;
In memory, we have: [_Py_slist_item, key_hash, key, data] where key size is
table->key_size bytes (not stored in each table entry, only in the stable).
Pointer to key and data is computed with these macros:
#define _Py_HASHTABLE_ENTRY_PKEY(ENTRY) \
((const void *)((char *)(ENTRY) \
+ sizeof(_Py_hashtable_entry_t)))
#define _Py_HASHTABLE_ENTRY_PDATA(TABLE, ENTRY) \
((const void *)((char *)(ENTRY) \
+ sizeof(_Py_hashtable_entry_t) \
+ (TABLE)->key_size))
But this approach is more annoying to use, it requires to play with pointers
and requires such ugly macros.
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Python tracker <[email protected]>
<https://bugs.python.org/issue40120>
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