gistfile1.c

  enum ValueType 
  {
    NULL,
    UNDEFINED,
    NUMBER_INT,
    NUMBER_DOUBLE,
    STRING,
    BOOLEAN,
    FUNCTION,
    OBJECT,
    TYPED_ARRAY // new in es6
  };
  
  struct StringBuffer
  {
    wchar *begin; // js strings is 2 bytes ie wide char
    int length;
    int refCount; // ref counter garbadge collection possible because string primitive is mutable type ie 
                  // var a = b in a we will have new string with same buffer, begin and length. buffer.refCount++
  };
  
  struct String
  {
    StringBuffer *buffer;
    wchar *begin;
    int length;
  };
  
  struct HashTableEntry // 32 bytes
  {
    int hash;
    
    String key; // string because key is used in for in loop
    
    Value value;
  };
  
  struct HashTable // Open addressing Hash Table with linear probing
  {
    HashTableEntry *entries; 
    int entriesCount;
  };
  
  struct Object
  {
    HashTable ownProperties;
    Object *prototype;
  };

  struct Function
  {
    void (*codeBegin)();
    int argumentsCount;
    Object *object; 
  };
  
  struct TypedArrayBuffer
  {
    void *begin;
    int length;
  };
  
  struct TypedArray
  {
    TypedArrayBuffer *buffer;
    void *begin;
    int length;
  };
  
  struct Value  // 16 bytes
  {
    VarableType varableType; // 4 bytes, not 1 to aligined memory
    union // 12 bytes
    {
      int numberIntValue; // 4 bytes
      double numberDoubleValue; // 8 bytes
      int booleanValue; // 4 bytes
      String stringValue; // 12 bytes
      Function functionValue; // 12 bytes
      Object objectValue; // 12 bytes
      TypedArray typedArrayValue; // 12 bytes
    }; 
  };