Issue 5142 - Convert Element Hiding to C++

compiled/Map.h

Index: compiled/Map.h
===================================================================
--- a/compiled/Map.h
+++ b/compiled/Map.h
@@ -140,19 +140,17 @@
 
     void resize(size_type bucketCount)
     {
       std::unique_ptr<entry_type[]> oldBuckets(std::move(mBuckets));
       size_type oldCount = mBucketCount;
 
       mEntryCount = 0;
       mBucketCount = bucketCount;
-      mBuckets.reset(new entry_type[mBucketCount]);
-      // Working around https://github.com/waywardmonkeys/emscripten-trace-collector/issues/2 here
-      annotate_address(reinterpret_cast<size_type*>(mBuckets.get()) - 1, "Hash table buffer");
+      allocate();
 
       // Copy old entries into the new buffer
       for (size_type i = 0; i < oldCount; i++)
       {
         entry_type& entry = oldBuckets[i];
         if (!entry.is_invalid() && !entry.is_deleted())
         {
           *find_bucket(entry.first) = entry;
@@ -174,28 +172,39 @@
 #if defined(DEBUG)
         mInsertCounter++;
 #endif
       }
       *existing = entry;
       return existing;
     }
 
+    void allocate()
+    {
+      mBuckets.reset(new entry_type[mBucketCount]);
+      // Working around https://github.com/waywardmonkeys/emscripten-trace-collector/issues/2 here
+      annotate_address(reinterpret_cast<size_type*>(mBuckets.get()) - 1, "Hash table buffer");
+    }
+
   public:
     explicit HashContainer(size_type expectedEntries = 0)
         : mEntryCount(0)
     {
       expectedEntries = ceil(expectedEntries / LOAD_FACTOR);
       mBucketCount = MIN_BUCKETS;
       while (mBucketCount < expectedEntries)
         mBucketCount <<= 1;
 
-      mBuckets.reset(new entry_type[mBucketCount]);
-      // Working around https://github.com/waywardmonkeys/emscripten-trace-collector/issues/2 here
-      annotate_address(reinterpret_cast<size_type*>(mBuckets.get()) - 1, "Hash table buffer");
+      allocate();
+    }
+
+    void clear()
+    {
+      mEntryCount = 0;
+      allocate();
     }
 
     void insert(const entry_type& entry)
     {
       assign(find_bucket(entry.first), entry);
     }
 
     bool erase(const key_type& key)
@@ -218,16 +227,21 @@
       return const_iterator(&mBuckets[0], &mBuckets[mBucketCount]);
     }
 
     const_iterator end() const
     {
       return const_iterator(&mBuckets[mBucketCount], &mBuckets[mBucketCount]);
     }
 
+    bool empty() const
+    {
+      return mEntryCount == 0;
+    }
+
     size_type size() const
     {
       return mEntryCount;
     }
   };
 
   template<typename Entry>
   struct MapReference : public HashContainerReference<Entry>