v1.1.0

hm.h

@@ -1,4 +1,4 @@
-// hm.h - v1.0.1 - MIT License
+// hm.h - v1.1.0 - MIT License
 // chained hash table implementation as a single header library.
 //
 // [License and changelog]
@@ -74,8 +74,8 @@
 //     bool hm_put(HashMap *hm, const void *key, const void *value)
 //
 // This function inserts a new value associated with the specified key. If the
-// key already exists, it's value will be overridden. Return false on error
-// only if HM_NO_ASSERT is not defined.
+// key already exists, it's value will be overridden. Returns false on error
+// only if HM_NO_ASSERT is defined.
 //
 //     void *hm_get(const HashMap *hm, const void *key)
 //
@@ -87,10 +87,16 @@
 // This function removes the entry associated with the specified key. Returns
 // whether the key was found and removed or not.
 //
+//     size_t hm_count(const HashMap *hm)
+//
+// Returns the number of elements stored in the specified HashMap. Returns 0
+// if the parameter is NULL.
+//
 //     HashMapIterator hm_iterate(const HashMap *hm)
 //
 // This function creates a HashMapIterator used to iterate the specfied
-// HashMap.
+// HashMap. Note that the returned iterator does not start from the first
+// element of the HashMap. You'll need to call hm_next() at least once.
 //
 //     const void *hm_key(const HashMapIterator *it)
 //
@@ -106,6 +112,10 @@
 //
 // This function iterates through the next entry of the HashMap and returns
 // it's value. Returns NULL if the iterator reached the end of the HashMap.
+//
+// [Notes]
+//
+// This library is not thread-safe.
 
 #ifndef HM_H_
 #define HM_H_
@@ -181,6 +191,7 @@ void hm_free(HashMap *hm);
 bool hm_put(HashMap *hm, const void *key, const void *value);
 void *hm_get(const HashMap *hm, const void *key);
 bool hm_remove(HashMap *hm, const void *key);
+size_t hm_count(const HashMap *hm);
 
 // Iterator functions
 HashMapIterator hm_iterate(const HashMap *hm);
@@ -220,7 +231,11 @@ HashMap hm_create(size_t key_size, size_t value_size)
 
 void hm_free(HashMap *hm)
 {
-    if (hm == NULL || hm->map == NULL) {
+    if (hm == NULL) {
+        return;
+    }
+
+    if (hm->map == NULL) {
         memset(hm, 0, sizeof(*hm));
         return;
     }
@@ -253,12 +268,12 @@ bool hm_put(HashMap *hm, const void *key, const void *value)
 
     // Ensure that HashMap is initialised
     if (hm->map == NULL) {
-        hm->map = (Hm__Bucket**)HM_REALLOC(NULL, sizeof(*hm->map) * HM_INITIAL_CAPACITY);
+        hm->capacity = HM_INITIAL_CAPACITY;
+        hm->map = (Hm__Bucket**)HM_REALLOC(NULL, sizeof(*hm->map) * hm->capacity);
         if (hm->map == NULL) {
             HM_ASSERT(false && "Reallocation failed");
             return false;
         }
-        hm->capacity = HM_INITIAL_CAPACITY;
         memset(hm->map, 0, sizeof(*hm->map) * hm->capacity);
     }
 
@@ -284,7 +299,7 @@ bool hm_put(HashMap *hm, const void *key, const void *value)
         }
 
         // Fixed or equal value_size
-        if (hm->value_size != 0 || value_size == cur->value_size) {
+        if (value_size == cur->value_size) {
             memcpy(cur->value, value, value_size);
             return true;
         }
@@ -301,6 +316,7 @@ bool hm_put(HashMap *hm, const void *key, const void *value)
         uint8_t *new_value = (uint8_t*)HM_REALLOC(cur->value, value_size);
         if (new_value == NULL) {
             HM_ASSERT(false && "Reallocation failed");
+            HM_FREE(tmp);
             return false;
         }
         cur->value = new_value;
@@ -394,6 +410,15 @@ bool hm_remove(HashMap *hm, const void *key)
     return false;
 }
 
+size_t hm_count(const HashMap *hm)
+{
+    if (hm == NULL) {
+        return 0;
+    }
+
+    return hm->count;
+}
+
 HashMapIterator hm_iterate(const HashMap *hm)
 {
     HashMapIterator it;
@@ -415,8 +440,8 @@ const void *hm_key(const HashMapIterator *it)
         return NULL;
     }
 
-    // Reached the end
-    if (it->end) {
+    // Error or reached the end
+    if (it->end || it->bucket == NULL) {
         return NULL;
     }
 
@@ -430,8 +455,8 @@ void *hm_value(const HashMapIterator *it)
         return NULL;
     }
 
-    // Reached the end
-    if (it->end) {
+    // Error or reached the end
+    if (it->end || it->bucket == NULL) {
         return NULL;
     }
 
@@ -450,29 +475,48 @@ void *hm_next(HashMapIterator *it)
         return NULL;
     }
 
-    if (it->bucket == NULL) {
-        // Find first list of buckets
-        while ((it->bucket = it->hm->map[it->index++]) == NULL);
-        return it->bucket->value;
+    const HashMap *hm = it->hm;
+
+    // Empty HashMap
+    if (hm->count == 0) {
+        it->end = true;
+        it->bucket = NULL;
+        it->index = hm->capacity;
+        return NULL;
     }
 
-    // Next bucket
+    // Find first list of buckets when iterator hasn't started yet
+    if (it->bucket == NULL) {
+        while (it->index < hm->capacity) {
+            it->bucket = hm->map[it->index++];
+            if (it->bucket != NULL) {
+                return it->bucket->value;
+            }
+        }
+        it->end = true;
+        it->bucket = NULL;
+        it->index = hm->capacity;
+        return NULL;
+    }
+
+    // Advance within current chain
     if (it->bucket->next != NULL) {
         it->bucket = it->bucket->next;
         return it->bucket->value;
     }
 
-    // Find next list of buckets
-    while ((it->bucket = it->hm->map[++it->index]) == NULL);
-
-    // Reached the end
-    if (it->index >= it->hm->capacity) {
-        it->end = true;
-        return NULL;
+    // Move to next non-empty bucket array slot
+    while (it->index < hm->capacity) {
+        it->bucket = hm->map[it->index++];
+        if (it->bucket != NULL) {
+            return it->bucket->value;
+        }
     }
 
-    it->bucket = it->hm->map[it->index];
-    return it->bucket->value;
+    it->end = true;
+    it->bucket = NULL;
+    it->index = hm->capacity;
+    return NULL;
 }
 
 uint64_t hm__fnv1a(const void *buffer, size_t size)
@@ -482,6 +526,8 @@ uint64_t hm__fnv1a(const void *buffer, size_t size)
         return 0;
     }
 
+    // TODO: When buffer is NULL terminated, the NULL is included in the hash
+
     const uint8_t *b = (const uint8_t*)buffer;
     uint64_t hash = 14695981039346656037ULL;
 
@@ -593,7 +639,6 @@ Hm__Bucket *hm__bucket_create(const void *key, size_t key_size, const void *valu
         HM_FREE(bucket);
         return NULL;
     }
-    memset(bucket->key, 0, key_size);
 
     // Allocate value
     bucket->value = HM_REALLOC(NULL, value_size);
@@ -603,7 +648,6 @@ Hm__Bucket *hm__bucket_create(const void *key, size_t key_size, const void *valu
         HM_FREE(bucket);
         return NULL;
     }
-    memset(bucket->value, 0, value_size);
 
     // Copy Key-value data
     memcpy(bucket->key, key, key_size);
@@ -622,6 +666,11 @@ Hm__Bucket *hm__bucket_create(const void *key, size_t key_size, const void *valu
 /*
  * Revision history:
  *
+ *     1.1.0 (2026-01-10) Added new hm_count() function;
+ *                        Fix value_size comparison in hm_put();
+ *                        Fix memory leak on failed reallocation in hm_put();
+ *                        Fix out-of-bounds access in hm_next();
+ *                        Improved documentation
  *     1.0.1 (2025-12-30) Added documentation
  *     1.0.0 (2025-11-18) Initial release
  */