init

map.c

@@ -0,0 +1,103 @@
+#include "map.h"
+
+#include <stdlib.h>
+
+#include "util.h"
+
+#define MAP_INITIAL_CAP 32 /* must be a power of 2 in this implementation */
+#define MAP_REHASH_THRESHOLD 0.7
+
+static void init_with_cap(Map *m, size_t val_size, size_t cap);
+static void rehash(Map *m);
+
+static void init_with_cap(Map *m, size_t val_size, size_t cap) {
+	m->len = 0;
+	m->cap = cap;
+	m->val_size = val_size;
+	void *data = malloc(sizeof(MapSlot) * cap + val_size * cap);
+	m->slots = data;
+	m->vals = m->slots + cap;
+	for (size_t i = 0; i < cap; i++) {
+		m->slots[i] = (MapSlot){
+			.empty = true,
+		};
+	}
+}
+
+static void rehash(Map *m) {
+	size_t old_cap = m->cap;
+	MapSlot *old_slots = m->slots;
+	void *old_vals = m->vals;
+	init_with_cap(m, m->val_size, m->cap * 2);
+	for (size_t i = 0; i < old_cap; i++) {
+		if (!old_slots[i].empty) {
+			map_insert(m, old_slots[i].key, (uint8_t*)old_vals + m->val_size * i);
+			if (old_slots[i].heap_alloc)
+				free(old_slots[i].key);
+			/* TODO: Don't reallocate big keys. */
+		}
+	}
+	free(old_slots);
+}
+
+void map_init(Map *m, size_t val_size) {
+	init_with_cap(m, val_size, MAP_INITIAL_CAP);
+}
+
+void map_term(Map *m) {
+	for (size_t i = 0; i < m->cap; i++) {
+		if (!m->slots[i].empty && m->slots[i].heap_alloc)
+			free(m->slots[i].key);
+	}
+	free(m->slots);
+}
+
+bool map_insert(Map *m, const char *key, const void *val) {
+	if ((double)m->len / (double)m->cap > MAP_REHASH_THRESHOLD)
+		rehash(m);
+	size_t idx = fnv1a32(key, strlen(key)) & (m->cap - 1);
+	bool replaced;
+	for (;;) {
+		if (m->slots[idx].empty) {
+			replaced = false;
+			m->len++;
+			break;
+		} else {
+			if (streq(m->slots[idx].key, key)) {
+				replaced = true;
+				break;
+			} else {
+				if (++idx == m->cap) idx = 0;
+			}
+		}
+	}
+	m->slots[idx].empty = false;
+	size_t keylen = strlen(key);
+	if (keylen <= MAP_SMALLKEY_SIZE-1) {
+		strcpy(m->slots[idx].smallkey, key);
+		m->slots[idx].key = m->slots[idx].smallkey;
+		m->slots[idx].heap_alloc = false;
+	} else {
+		m->slots[idx].key = sndup(key, keylen);
+		m->slots[idx].heap_alloc = true;
+	}
+	memcpy((uint8_t*)m->vals + m->val_size * idx, val, m->val_size);
+	return replaced;
+}
+
+bool map_get(Map *m, const char *key, void *out_val) {
+	size_t idx = fnv1a32(key, strlen(key)) & (m->cap - 1);
+	for (;;) {
+		if (m->slots[idx].empty)
+			return false;
+		else {
+			if (streq(m->slots[idx].key, key)) {
+				if (out_val)
+					memcpy(out_val, (uint8_t*)m->vals + m->val_size * idx, m->val_size);
+				return true;
+			} else {
+				if (++idx == m->cap) idx = 0;
+			}
+		}
+	}
+}