From e5eae3786fa0c846a3e01f2758e7dfa481a27410 Mon Sep 17 00:00:00 2001 From: Jelte Fennema-Nio Date: Thu, 4 Dec 2025 15:39:00 +0100 Subject: [PATCH v2 4/5] Add foreach_hash macro For lists we've had a new foreach style macros since 14dd0f27d7. This adds a similar macro for hash tables. This new foreach_hash macro makes iterating over the items in an HTAB as simple as iterating over the items in a List. The only additional thing to keep in mind is that when exiting the loop early you need to call foreach_hash_term. --- src/include/utils/hsearch.h | 46 +++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/src/include/utils/hsearch.h b/src/include/utils/hsearch.h index 36b31be7ad6..b3a361d78ad 100644 --- a/src/include/utils/hsearch.h +++ b/src/include/utils/hsearch.h @@ -277,6 +277,52 @@ typedef struct uint32 hashvalue; /* hashvalue to start seqscan over hash */ } HASH_SEQ_STATUS; +/* + * foreach_hash - iterate over all entries in a hash table + * + * This macro simplifies hash table iteration by combining hash_seq_init + * and hash_seq_search into a single for-loop construct. + * + * Usage: + * foreach_hash(MyEntry, entry, my_hashtable) + * { + * // use entry + * } + * + * This replaces the more verbose pattern: + * HASH_SEQ_STATUS status; + * MyEntry *entry; + * hash_seq_init(&status, my_hashtable); + * while ((entry = (MyEntry *) hash_seq_search(&status)) != NULL) + * { + * // use entry + * } + * + * For early termination, use foreach_hash_term() before break: + * foreach_hash(MyEntry, entry, my_hashtable) + * { + * if (found_it) + * { + * foreach_hash_term(entry); + * break; + * } + * } + */ +#define foreach_hash(type, var, htab) \ + for (type *var = 0, *var##__outerloop = (type *) 1; \ + var##__outerloop; \ + var##__outerloop = 0) \ + for (HASH_SEQ_STATUS var##__status = (hash_seq_init(&var##__status, (htab)), var##__status); \ + (var = (type *) hash_seq_search(&var##__status)) != NULL; \ + ) + +/* + * foreach_hash_term - terminate a foreach_hash loop early + * + * Call this before 'break' to properly clean up the hash scan. + */ +#define foreach_hash_term(var) hash_seq_term(&var##__status) + /* * prototypes for functions in dynahash.c */ -- 2.52.0