1 files changed, 132 insertions, 0 deletions
diff --git a/src/hashmap.c b/src/hashmap.c
new file mode 100644
index 0000000..038678a
--- /dev/null
+++ b/src/hashmap.c
@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2023 Johnny Richard
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#include "hashmap.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static uint32_t
+u32_fnv1a_hash(const char *s);
+static void
+hashmap_init(hashmap_t *map);
+static char *
+__strdup(const char *s);
+
+hashmap_t *
+hashmap_new(void)
+{
+  hashmap_t *map = (hashmap_t *)malloc(sizeof(hashmap_t));
+  if (map == NULL) {
+    fprintf(stderr, "[FATAL] Out of memory: hashmap_new: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+
+  hashmap_init(map);
+  return map;
+}
+
+static void
+hashmap_init(hashmap_t *map)
+{
+  assert(map);
+  map->entries = (hashmap_entry_t *)calloc(HASHMAP_INITIAL_CAPACITY, sizeof(hashmap_entry_t));
+  if (map->entries == NULL) {
+    fprintf(stderr, "[FATAL] Out of memory: hashmap_init: %s\n", strerror(errno));
+    exit(EXIT_FAILURE);
+  }
+  map->capacity = HASHMAP_INITIAL_CAPACITY;
+}
+
+static uint32_t
+u32_fnv1a_hash(const char *s)
+{
+  uint32_t hash = U32_FNV1A_OFFSET_BASIS;
+  size_t len = strlen(s);
+  for (size_t i = 0; i < len; ++i) {
+    hash ^= s[i];
+    hash *= U32_FNV1A_PRIME;
+  }
+  return hash;
+}
+
+bool
+hashmap_put(hashmap_t *map, char *key, void *value)
+{
+  assert(map && key);
+  uint32_t hash = u32_fnv1a_hash(key);
+  hashmap_entry_t *entry = &(map->entries[hash & (map->capacity - 1)]);
+
+  while (entry != NULL) {
+    if (entry->hash == hash && strcmp(entry->key, key) == 0) {
+      entry->value = value;
+      return true;
+    }
+    if (entry->next == NULL)
+      break;
+    entry = entry->next;
+  }
+  entry->next = (hashmap_entry_t *)malloc(sizeof(hashmap_entry_t));
+  *entry->next = (hashmap_entry_t){ .key = __strdup(key), .hash = hash, .value = value, .next = NULL };
+  return true;
+}
+
+void *
+hashmap_get(hashmap_t *map, char *key)
+{
+  uint32_t hash = u32_fnv1a_hash(key);
+  hashmap_entry_t *entry = &map->entries[hash & (map->capacity - 1)];
+  while (entry != NULL) {
+    if (entry->hash == hash && strcmp(entry->key, key) == 0) {
+      return entry->value;
+    }
+    entry = entry->next;
+  }
+  return NULL;
+}
+
+void
+hashmap_destroy(hashmap_t *map)
+{
+  for (size_t i = 0; i < map->capacity; ++i) {
+    hashmap_entry_t *entry = &map->entries[i];
+    while (entry != NULL) {
+      if (entry->key != NULL)
+        free(entry->key);
+      entry = entry->next;
+    }
+  }
+  free(map->entries);
+  free(map);
+}
+
+static char *
+__strdup(const char *s)
+{
+  size_t slen = strlen(s);
+  char *result = malloc(slen + 1);
+  if (result == NULL) {
+    return NULL;
+  }
+
+  memcpy(result, s, slen + 1);
+  return result;
+}