From 259bae805cef9354b2579d16e192d8268cb68949 Mon Sep 17 00:00:00 2001
From: Sara <sara@saragerretsen.nl>
Date: Sat, 4 Nov 2023 19:18:28 +0100
Subject: [PATCH] added hashmap

---
 src/map.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/map.h | 28 +++++++++++++++++++
 2 files changed, 109 insertions(+)
 create mode 100644 src/map.c
 create mode 100644 src/map.h

diff --git a/src/map.c b/src/map.c
new file mode 100644
index 0000000..870a553
--- /dev/null
+++ b/src/map.c
@@ -0,0 +1,81 @@
+#include "map.h"
+#include "memory.h"
+#include "math.h"
+#include "debug.h"
+
+HashMap hash_map_from_sizes(size_t ksize, size_t vsize, HashFn hasher) {
+    return (HashMap) {
+        .data = list_init(ksize + vsize + sizeof(uintptr_t)),
+        .hasher = hasher,
+        .key_size = ksize,
+        .value_size = vsize,
+    };
+}
+
+void hash_map_empty(HashMap* self) {
+    list_empty(&self->data);
+}
+
+static inline
+uintptr_t _internal_get_hash(HashMap* self, size_t at) {
+    return *list_at_as(uintptr_t, &self->data, at);
+}
+
+static inline
+void* _internal_get_key(HashMap* self, size_t at) {
+    return (void*)(list_at_as(uint8_t, &self->data, at) + sizeof(uintptr_t) + self->value_size);
+}
+
+static inline
+void* _internal_get_value(HashMap* self, size_t at) {
+    return (void*)(list_at_as(uint8_t, &self->data, at) + sizeof(uintptr_t));
+}
+
+static inline
+size_t _internal_search(HashMap* self, uintptr_t hash) {
+    int left = 0;
+    int right = self->data.len - 1;
+    int m;
+
+    while(left <= right) {
+        m = floor((float)(left + right) / 2.0);
+        if(*list_at_as(uintptr_t, &self->data, m) < hash) {
+            left = m + 1;
+        } else if(*list_at_as(uintptr_t, &self->data, m) > hash) {
+            right = m - 1;
+        } else {
+            return m;
+        }
+    }
+
+    return self->data.len;
+}
+
+void hash_map_insert(HashMap* self, void* key, void* value) {
+    const uintptr_t hash = self->hasher(key);
+    const size_t target_index = _internal_search(self, hash);
+
+    list_reserve(&self->data, self->data.len + 1);
+    self->data.len += 1;
+
+    uint8_t* target_address = list_at(&self->data, target_index);
+
+    uintptr_t* target_hash = (uintptr_t*)target_address;
+    uint8_t* target_value = target_address + sizeof(uintptr_t);
+    uint8_t* target_key = target_value + self->value_size;
+
+    *target_hash = hash;
+    memcpy(target_value, value, self->value_size);
+    memcpy(target_key, key, self->key_size);
+}
+
+void hash_map_erase(HashMap* self, void* key) {
+    const size_t target_index = _internal_search(self, self->hasher(key));
+    ASSERT_RETURN(target_index < self->data.len,, "Attempted to erase a hashmap by a key that is not in the hashmap");
+    list_erase(&self->data, target_index);
+}
+
+void* hash_map_at(HashMap* self, void* key) {
+    const size_t target_index = _internal_search(self, self->hasher(key));
+    return list_at(&self->data, target_index);
+}
diff --git a/src/map.h b/src/map.h
new file mode 100644
index 0000000..0652342
--- /dev/null
+++ b/src/map.h
@@ -0,0 +1,28 @@
+#ifndef _fencer_hashmap_h
+#define _fencer_hashmap_h
+
+#include "stdint.h"
+#include "list.h"
+
+typedef uintptr_t (*HashFn)(void*);
+
+typedef struct HashMap {
+    HashFn hasher;
+    List data;
+    size_t key_size;
+    size_t value_size;
+} HashMap;
+
+extern HashMap hash_map_from_sizes(size_t key_size, size_t value_size, HashFn hasher);
+extern void hash_map_empty(HashMap* self);
+extern void hash_map_insert(HashMap* self, void* key, void* value);
+extern void hash_map_erase(HashMap* self, void* key);
+extern void* hash_map_at(HashMap* self, void* key);
+
+#define hash_map_at_as(__Type, __Map, __Key)\
+    ((__Type*)hash_map_at(__Map, __Key))
+
+#define hash_map_from_types(__KType, __VType, __Hasher)\
+    (hash_map_from_sizes(sizeof(__KType), sizeof(_VType), __Hasher))
+
+#endif // !_fencer_hashmap_h