1 files changed, 139 insertions, 0 deletions
diff --git a/set.c b/set.c
new file mode 100644
index 0000000..e69cef0
--- /dev/null
+++ b/set.c
@@ -0,0 +1,139 @@
+#include "set.h"
+#include "crash.h"
+#include <stdlib.h>
+
+#define DEFAULT_CAPACITY 16
+#define TOMBSTONE_VAL ((void*)-1)
+
+void set_init(
+    set_t* set,
+    hash_func_t hash_func,
+    eq_func_t eq_func,
+    double load_limit
+) {
+    set_init_capacity(set, hash_func, eq_func, load_limit, DEFAULT_CAPACITY);
+}
+
+void set_init_capacity(
+    set_t* set,
+    hash_func_t hash_func,
+    eq_func_t eq_func,
+    double load_limit,
+    size_t capacity
+) {
+    set->hash_func = hash_func;
+    set->eq_func = eq_func;
+    set->load_limit = load_limit;
+    set->size = 0;
+    set->__num_buckets = capacity / load_limit + 1;
+    set->__buckets = calloc(set->__num_buckets, sizeof(void*));
+
+    if (set->__buckets == NULL)
+        crash("Out of memory allocating %ld hash buckets\n", set->__num_buckets);
+}
+
+void set_destroy(set_t* set) {
+    free(set->__buckets);
+}
+
+static size_t fetch_set_idx(
+    const set_t* set,
+    const void* key,
+    bool fetch_tombstones
+) {
+    if (key == NULL || key == TOMBSTONE_VAL)
+        crash("safec sets do not support non-address keys: %p.\n", key);
+    size_t base = set->hash_func(key) % set->__num_buckets;
+    size_t idx = base, i = 0, offset = 0;
+
+    for (;;) {
+        void* cur = set->__buckets[idx];
+        if (cur == NULL || (fetch_tombstones && cur == TOMBSTONE_VAL)
+                || (cur != TOMBSTONE_VAL && set->eq_func(key, cur)))
+            return idx;
+        if (offset >= set->__num_buckets) return set->__num_buckets;
+        i++;
+        offset = i * i;
+        idx = (base + offset) % set->__num_buckets;
+    }
+}
+
+bool set_contains(const set_t* set, const void* key) {
+    size_t idx = fetch_set_idx(set, key, false);
+    return idx < set->__num_buckets && set->__buckets[idx] != NULL;
+}
+
+void* set_get(const set_t* set, const void* key) {
+    return set_get_or_default(set, key, NULL);
+}
+
+void* set_get_or_default(const set_t* set, const void* key, void* default_key) {
+    size_t idx = fetch_set_idx(set, key, false);
+    if (idx >= set->__num_buckets) return default_key;
+    void* found = set->__buckets[idx];
+    return found == NULL ? default_key : found;
+}
+
+static void rehash_set(set_t* set) {
+    size_t old_num_buckets = set->__num_buckets;
+    void** old_buckets = set->__buckets;
+    set->__num_buckets <<= 1;
+    set->__buckets = calloc(set->__num_buckets, sizeof(void*));
+    if (set->__buckets == NULL)
+        crash(
+            "Out of memory allocating %ld hash buckets\n", set->__num_buckets);
+
+    for (size_t i = 0; i < old_num_buckets; i++) {
+        void* key = old_buckets[i];
+        if (key == NULL) continue;
+        size_t idx = fetch_set_idx(set, key, true);
+        if (idx >= set->__num_buckets)
+            crash(
+                "Set failed rehashing, likely due to bad hash function.\n");
+        set->__buckets[idx] = key;
+    }
+    free(old_buckets);
+}
+
+static size_t fetch_set_idx_rehashing(set_t* set, void* key) {
+    size_t idx = fetch_set_idx(set, key, true);
+    if ((double) ++set->size / set->__num_buckets > set->load_limit
+            || idx >= set->__num_buckets) {
+        rehash_set(set);
+        idx = fetch_set_idx(set, key, true);
+        if (idx >= set->__num_buckets)
+            crash(
+                "Set still full after rehashing, "
+                "likely due to bad hash function.\n");
+    }
+    return idx;
+}
+
+void* set_add(set_t* set, void* key) {
+    size_t idx = fetch_set_idx_rehashing(set, key);
+    void* old_key = set->__buckets[idx];
+    if (old_key != NULL) return old_key;
+    set->__buckets[idx] = key;
+    return key;
+}
+
+void set_put(set_t* set, void* key) {
+    size_t idx = fetch_set_idx_rehashing(set, key);
+    set->__buckets[idx] = key;
+}
+
+void* set_remove(set_t* set, const void* key) {
+    size_t idx = fetch_set_idx(set, key, false);
+    void* old_key = set->__buckets[idx];
+    if (old_key != NULL) set->size--;
+    set->__buckets[idx] = TOMBSTONE_VAL;
+    return old_key;   
+}
+
+void set_foreach(set_t* set, set_foreach_func_t foreach_func, void* data) {
+    for (size_t i = 0; i < set->__num_buckets; i++) {
+        void* key = set->__buckets[i];
+        if (key == NULL || key == TOMBSTONE_VAL) continue;
+        foreach_func(key, data);
+    }
+}