post-scarcity/src/c/payloads/hashtable.h

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1.6 KiB
C

/**
* payloads/hashtable.h
*
* an ordinary Lisp hashtable - one whose contents are immutable.
*
* Can sensibly sit in any pso from size class 6 upwards.
*
* (c) 2026 Simon Brooke <simon@journeyman.cc>
* Licensed under GPL version 2.0, or, at your option, any later version.
*/
#ifndef __psse_payloads_hashtable_h
#define __psse_payloads_hashtable_h
#include "memory/pointer.h"
/**
* @brief Tag for an ordinary Lisp hashtable - one whose contents are immutable.
* \see NAMESPACETAG for mutable hashtables.
*/
#define HASHTABLETAG "HTB"
/**
* The payload of a hashtable. The number of buckets is assigned at run-time,
* and is stored in n_buckets. Each bucket is something ASSOC can consume:
* i.e. either an assoc list or a further hashtable.
*/
struct hashtable_payload {
struct cons_pointer hash_fn; /* function for hashing values in this hashtable, or `NIL` to use
the default hashing function */
struct cons_pointer write_acl; /* it seems to me that it is likely that the
* principal difference between a hashtable and a
* namespace is that a hashtable has a write ACL
* of `NIL`, meaning not writeable by anyone */
uint32_t n_buckets; /* number of hash buckets */
uint32_t unused; /* for word alignment and possible later expansion */
struct cons_pointer buckets[]; /* actual hash buckets, which should be `NIL`
* or assoc lists or (possibly) further hashtables. */
};
#endif