Issue 5142 - Convert Element Hiding to C++

compiled/StringMap.h

Index: compiled/StringMap.h
===================================================================
--- a/compiled/StringMap.h
+++ b/compiled/StringMap.h
@@ -17,24 +17,38 @@
 
 #pragma once
 
 #include <cstddef>
 
 #include "Map.h"
 #include "String.h"
 
+class StringHash
+{
+public:
+  size_t operator()(const String& key) const
+  {
+    // FNV-1a hash function
+    size_t result = 2166136261;
+    for (size_t i = 0; i < key.length(); i++)
+      result = (result ^ key[i]) * 16777619;
+    return result;
+  }
+};
+
 namespace StringMap_internal
 {
   struct StringSetEntry
   {
     typedef String key_type;
     typedef size_t size_type;
 
     DependentString first;
+    static StringHash hashFunctor;
 
     StringSetEntry(const key_type& key = DependentString())
     {
       if (!key.is_invalid())
         first.reset(key);
     }
 
     bool equals(const key_type& other) const
@@ -54,21 +68,17 @@
 
     void erase()
     {
       first.erase();
     }
 
     static size_type hash(const key_type& key)
     {
-      // FNV-1a hash function
-      size_type result = 2166136261;
-      for (String::size_type i = 0; i < key.length(); i++)
-        result = (result ^ key[i]) * 16777619;
-      return result;
+      return hashFunctor(key);
     }
   };
 
   template<typename Value>
   struct StringMapEntry : StringSetEntry
   {
     typedef StringSetEntry super;
     typedef Value value_type;