Add internal hash table implementation

2026-09-21 22:15:54 +01:00
parent b014ffa3b1
commit 421728c137
4 changed files with 349 additions and 0 deletions
@@ -0,0 +1,99 @@
+// vim:fileencoding=utf-8:foldmethod=marker
+
+/**
+ * A hash table implementation with Robin Hood open addressing for collision resolution.
+ *
+ * The implementation is based on a version of this C++ implementation:
+ * https://github.com/martinus/unordered_dense
+ *
+ * Extra references:
+ * - https://faultlore.com/blah/robinhood-part-1/
+ * - https://blog.hieunt.me/blog/robinhood-hashing
+ *
+ * IMPORTANT:
+ * This is the internal hash table implementation and it is not intended to be used directly.
+ * Please check ../map/map.h and ../set/set.h for the public APIs.
+ */
+
+#ifndef TABLE_H
+#define TABLE_H
+
+#include "../hasher/hasher.h"
+#include "../../array/array.h"
+#include "../../mem/allocator/mem_allocator.h"
+#include "../../stream/stream.h"
+#include "../../../common/aliases/aliases.h"
+#include "../../../common/platform/platform.h"
+
+#ifdef WP_PLATFORM_CPP
+BEGIN_C_LINKAGE
+#endif // !WP_PLATFORM_CPP
+
+#define WP_HASH_TABLE_MAGIC     wpU64Const(0x57504854424c)
+#define WP_HASH_TAG_BITS        wpU64Const(32)
+#define WP_HASH_DIST_INC        (wpU64Const(1) << WP_HASH_TAG_BITS)
+#define WP_HASH_TAG_MASK        (WP_HASH_DIST_INC - wpU64Const(1))
+#define WP_HASH_MAX_LOAD_FACTOR 0.65f
+
+typedef WpU8Stream (*WpU8StreamEncoder)(void *data);
+typedef b8 (*WpKeyEqualTest)(void *a, void *b);
+
+typedef struct WpHashBucket {
+	u64 dist_and_tag;
+	u64 item_index;
+} WpHashBucket;
+typedef WpHashBucket *WpHashBucketArray;
+
+typedef struct WpHashTable {
+	WpHasher          hasher;
+	WpU8StreamEncoder encoder;
+	WpKeyEqualTest    key_eq;
+	WpArray           keys;
+	WpArray           values;
+	WpHashBucketArray buckets;
+	u64               magic;
+	u64               bucket_mask;
+	f32               load_factor;
+	b8                has_values;
+} WpHashTable;
+
+typedef struct WpHashBucketRef {
+	u64 dist_and_tag;
+	u64 bucket_index;
+} WpHashBucketRef;
+
+typedef struct WpHashLookupResult {
+	WpHashBucketRef ref;
+	b8              found;
+} WpHashLookupResult;
+
+void              *hashTableKeys(WpHashTable *table);
+void              *hashTableValues(WpHashTable *table);
+void              *hashTableGetKeyFromBucket(WpHashTable *table, WpHashBucket bucket, u64 key_size);
+void              *hashTableGetValueFromBucket(WpHashTable *table, WpHashBucket bucket, u64 value_size);
+void              *hashTableGetKeyFromBucketRef(WpHashTable *table, WpHashBucketRef ref, u64 key_size);
+void              *hashTableGetValueFromBucketRef(WpHashTable *table, WpHashBucketRef ref, u64 value_size);
+u64                hashTableCapacity(WpHashTable *table);
+u64                hashTableCount(WpHashTable *table);
+u64                hashTableKeySize(WpHashTable *table);
+u64                hashTableValueSize(WpHashTable *table);
+u64                hashTableCalcHash(WpHashTable *table, void *key, u64 key_size);
+void               hashTableGrow(WpHashTable *table, const WpAllocator *allocator, u64 key_size,
+                                 u64 value_size);
+WpHashLookupResult hashTableLookup(WpHashTable *table, void *key, WpHashBucketRef ref, u64 key_size);
+void               hashTableUpdate(WpHashTable *table, void *value, WpHashBucketRef ref, u64 value_size);
+void               hashTableInsert(WpHashTable *table, void *key, void *value, WpHashBucketRef ref,
+                                   u64 key_size, u64 value_size);
+void               hashTableRemove(WpHashTable *table, WpHashBucketRef ref, u64 key_size, u64 value_size);
+void               hashTableClear(WpHashTable *table, u64 key_size, u64 value_size);
+WpHashBucketRef    hashTableBucketRef(WpHashTable *table, u64 hash);
+u64                hashTableGetDist(u64 dist_and_tag);
+u64                hashTableNextBucket(WpHashTable *table, u64 bucket_index);
+u64                hashTableDistInc(u64 dist_and_tag);
+u64                hashTableDistDec(u64 dist_and_tag);
+
+#ifdef WP_PLATFORM_CPP
+END_C_LINKAGE
+#endif // !WP_PLATFORM_CPP
+
+#endif // !TABLE_H