From 4223904b183eae4e444e8af4d8eb5c9d1f937c71 Mon Sep 17 00:00:00 2001
From: Jake <jakeroggenbuck2@gmail.com>
Date: Sat, 3 Aug 2024 20:51:48 -0700
Subject: [PATCH] Add rehash after double

---
 src/util/hashmap.c   | 35 +++++++++++++++++++++++++++++++----
 src/util/hashmap.h   |  1 +
 src/util/test_util.c |  1 +
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/src/util/hashmap.c b/src/util/hashmap.c
index 4b43521..1cb3e9a 100644
--- a/src/util/hashmap.c
+++ b/src/util/hashmap.c
@@ -93,11 +93,20 @@ int hm_set(struct Hashmap *h, char *key, void *value) {
 }
 
 void double_cap(struct Hashmap *h) {
-    // TODO: rehash all the old elements
-    // They will be in the wrong spot after this
-    h->buckets = realloc(h->buckets, h->cap * 2 * sizeof(struct BucketNode *));
+    struct BucketNode **new_buckets =
+        calloc(h->cap * 2, sizeof(struct BucketNode *));
+
+    for (int i = 0; i < h->cap; i++) {
+
+        if (h->buckets[i] != NULL) {
+            struct BucketNode *b = h->buckets[i];
+            unsigned a = h->hash(b->key) % h->cap;
+            new_buckets[a] = b;
+        }
+    }
+
+    h->buckets = new_buckets;
 
-    h->size = 0;
     h->cap = h->cap * 2;
 }
 
@@ -145,3 +154,21 @@ int test_hash_set_and_get() {
 
     return 0;
 }
+
+int test_hash_set_and_double_get() {
+    testing_func_setup();
+    struct Hashmap *h = create_hashmap(100);
+
+    char name[100] = "jake";
+    char key[10] = "test";
+
+    int ret = hm_set(h, key, name);
+    tassert(ret != -1);
+
+    double_cap(h);
+
+    struct BucketNode *got = hm_get(h, "test");
+    tassert(strcmp(got->value, "jake") == 0);
+
+    return 0;
+}
diff --git a/src/util/hashmap.h b/src/util/hashmap.h
index ef57a3b..80c9b03 100644
--- a/src/util/hashmap.h
+++ b/src/util/hashmap.h
@@ -29,3 +29,4 @@ void double_cap(struct Hashmap *h);
 int test_hash_init();
 int test_hash_init_and_store();
 int test_hash_set_and_get();
+int test_hash_set_and_double_get();
diff --git a/src/util/test_util.c b/src/util/test_util.c
index 83ea4c1..413a5f3 100644
--- a/src/util/test_util.c
+++ b/src/util/test_util.c
@@ -7,6 +7,7 @@ int test_util() {
     test_hash_init();
     test_hash_init_and_store();
     test_hash_set_and_get();
+	test_hash_set_and_double_get();
 
     testing_module_cleanup();
     return 0;