Add HashTable::remove() and fix a bug where ConstIterator would skip the first.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/c2ef54c0449

AK/HashTable.h

@@ -186,12 +186,12 @@ public:
         {
             if (!isEnd && !m_table.isEmpty() && !(m_bucketIterator != DoublyLinkedList<T>::ConstIterator::universalEnd())) {
 #ifdef HASHTABLE_DEBUG
-                printf("bucket iterator init!\n");
+                printf("const bucket iterator init!\n");
 #endif
                 const DoublyLinkedList<T>& chain = m_table.m_buckets[0].chain;
                 m_bucketIterator = chain.begin();
-                
-                skipToNext();
+                if (m_bucketIterator.isEnd())
+                    skipToNext();
             }
         }
 
@@ -207,6 +207,15 @@ public:
     Iterator find(const T&);
     ConstIterator find(const T&) const;
 
+    void remove(const T& value)
+    {
+        auto it = find(value);
+        if (it != end())
+            remove(it);
+    }
+
+    void remove(Iterator&);
+
 private:
     Bucket& lookup(const T&);
     const Bucket& lookup(const T&) const;
@@ -315,6 +324,14 @@ auto HashTable<T, TraitsForT>::find(const T& value) const -> ConstIterator
     return end();
 }
 
+template<typename T, typename TraitsForT>
+void HashTable<T, TraitsForT>::remove(Iterator& it)
+{
+    ASSERT(!isEmpty());
+    m_buckets[it.m_bucketIndex].chain.remove(it.m_bucketIterator);
+    --m_size;
+}
+
 template<typename T, typename TraitsForT>
 typename HashTable<T, TraitsForT>::Bucket& HashTable<T, TraitsForT>::lookup(const T& value)
 {

AK/test.cpp

@@ -155,5 +155,33 @@ int main(int, char**)
         printInts(v);
     }
 
+    {
+        auto printInts = [] (const HashTable<int>& h) {
+            printf("HashTable {\n    size: %u\n    capacity: %u\n    elements: ", h.size(), h.capacity());
+            for (auto i : h)
+                printf("%d ", i);
+            printf("\n}\n");
+        };
+
+        HashTable<int> h;
+
+        h.set(10);
+        h.set(20);
+        h.set(30);
+        h.set(40);
+        h.set(50);
+
+        h.dump();
+
+        printInts(h);
+
+        h.remove(30);
+        printInts(h);
+
+        h.set(30);
+        h.remove(30);
+        printInts(h);
+    }
+
     return 0;
 }