From b7b6a6a8d5ce3748c07c4e789b954ec9d22813ba Mon Sep 17 00:00:00 2001
From: "william.valenduc" <william.valenduc@epita.fr>
Date: Sat, 17 Jan 2026 22:45:27 +0000
Subject: [PATCH] feat(hash_map): hash_map

---
 src/utils/hash_map/hash_map.c | 173 ++++++++++++++++++++++++++++++++++
 src/utils/hash_map/hash_map.h |  34 +++++++
 2 files changed, 207 insertions(+)
 create mode 100644 src/utils/hash_map/hash_map.c
 create mode 100644 src/utils/hash_map/hash_map.h

diff --git a/src/utils/hash_map/hash_map.c b/src/utils/hash_map/hash_map.c
new file mode 100644
index 0000000..dec698c
--- /dev/null
+++ b/src/utils/hash_map/hash_map.c
@@ -0,0 +1,173 @@
+#include "hash_map.h"
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/*
+** Hash the key using FNV-1a 32 bits hash algorithm.
+*/
+static size_t hash(const char *key)
+{
+    if (key == NULL)
+        return 0;
+
+    uint32_t hash = 2166136261; // FNV offset basis
+    uint32_t prime = 16777619; // FNV prime
+
+    while (*key != 0)
+    {
+        hash ^= *key;
+        hash *= prime;
+        key++;
+    }
+
+    return hash;
+}
+
+struct hash_map *hash_map_init(size_t size)
+{
+    struct hash_map *p = malloc(sizeof(struct hash_map));
+    if (p != NULL)
+    {
+        p->data = calloc(size, sizeof(struct pair_list *));
+        if (p->data == NULL)
+        {
+            free(p);
+            return NULL;
+        }
+        p->size = size;
+    }
+    return p;
+}
+
+bool hash_map_insert(struct hash_map *hash_map, const char *key, void *value,
+                     bool *updated)
+{
+    if (hash_map == NULL || hash_map->size == 0 || key == NULL)
+        return false;
+
+    size_t h = hash(key);
+    struct pair_list **l = hash_map->data;
+    size_t i = h % hash_map->size;
+
+    if (l[i] != NULL)
+    {
+        // check if key is in linked list
+        struct pair_list *iter = l[i];
+        while (iter)
+        {
+            if (strcmp(iter->key, key) == 0)
+            {
+                // update
+                iter->value = value;
+                if (updated)
+                    *updated = true;
+                return true;
+            }
+            iter = iter->next;
+        }
+
+        // if not found => collision
+    }
+    struct pair_list *p = malloc(sizeof(struct pair_list));
+    if (p == NULL)
+        return false;
+
+    if (updated)
+        *updated = false;
+
+    p->key = key;
+    p->value = value;
+    p->next = l[i];
+    l[i] = p;
+    l[i] = p;
+    return true;
+}
+
+void hash_map_free(struct hash_map *hash_map)
+{
+    struct pair_list *l;
+    struct pair_list *prev;
+
+    if (hash_map)
+    {
+        for (size_t i = 0; i < hash_map->size; i++)
+        {
+            l = hash_map->data[i];
+            while (l != NULL)
+            {
+                prev = l;
+                l = l->next;
+                free(prev);
+            }
+        }
+        free(hash_map->data);
+        free(hash_map);
+    }
+}
+
+void hash_map_foreach(struct hash_map *hash_map,
+                      void (*fn)(const char *, const void *))
+{
+    if (hash_map == NULL)
+        return;
+
+    struct pair_list *iter;
+    for (size_t i = 0; i < hash_map->size; i++)
+    {
+        iter = hash_map->data[i];
+        while (iter != NULL)
+        {
+            fn(iter->key, iter->value);
+            iter = iter->next;
+        }
+    }
+}
+
+const void *hash_map_get(const struct hash_map *hash_map, const char *key)
+{
+    if (hash_map == NULL || hash_map->size == 0)
+        return NULL;
+
+    size_t h = hash(key);
+    size_t i = h % hash_map->size;
+    struct pair_list *l = hash_map->data[i];
+    while (l != NULL)
+    {
+        if (strcmp(l->key, key) == 0)
+            return l->value;
+        l = l->next;
+    }
+    return NULL;
+}
+
+bool hash_map_remove(struct hash_map *hash_map, const char *key)
+{
+    if (hash_map == NULL || hash_map->size == 0)
+        return false;
+
+    size_t h = hash(key);
+    size_t i = h % hash_map->size;
+    struct pair_list *l = hash_map->data[i];
+    struct pair_list *p = NULL;
+
+    while (l != NULL)
+    {
+        if (strcmp(l->key, key) == 0)
+        {
+            if (p != NULL)
+                p->next = l->next;
+            else
+                hash_map->data[i] = l->next;
+            free(l);
+            return true;
+        }
+        p = l;
+        l = l->next;
+    }
+    return false;
+}
diff --git a/src/utils/hash_map/hash_map.h b/src/utils/hash_map/hash_map.h
new file mode 100644
index 0000000..efdabc2
--- /dev/null
+++ b/src/utils/hash_map/hash_map.h
@@ -0,0 +1,34 @@
+#ifndef HASH_MAP_H
+#define HASH_MAP_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+struct pair_list
+{
+    const char *key;
+    void *value;
+    struct pair_list *next;
+};
+
+struct hash_map
+{
+    struct pair_list **data;
+    size_t size;
+};
+
+struct hash_map *hash_map_init(size_t size);
+
+bool hash_map_insert(struct hash_map *hash_map, const char *key, void *value,
+                     bool *updated);
+
+void hash_map_free(struct hash_map *hash_map);
+
+void hash_map_foreach(struct hash_map *hash_map,
+                      void (*fn)(const char *, const void *));
+
+const void *hash_map_get(const struct hash_map *hash_map, const char *key);
+
+bool hash_map_remove(struct hash_map *hash_map, const char *key);
+
+#endif /* ! HASH_MAP_H */