AArray
 Description:
  A PHP styled associative array for C++.
 Details:
  An associative array can behave like a vector, map, hashtable,
  dictionary, list, set, etc. It is a set of key-value pairs where
  the key can be either an integer or a std::string. Internally the
  two types of keys are stored in different structures. In particular,
  accessing an arbitrary integer key will allocate all uninitialized
  integer keys below it to nulls.
    The values can be a variety of types: null (uninitialized), bool,
  int, real (double), string (std::string), or another AArray. In this
  way, multidimensional arrays can be created, as well as tree structures,
  and general hierarchical data structures.
    One of the most powerful features is the serialization/deserialization
  via stream operators. The entire AArray structure can be (human-readably)
  serialized to a stream and then read back in again. This makes the
  AArray an attractive lightweight structured data parser. Also, the
  serialization format can be customized to provide a reasonable syntax
  for hand editting.
 Example:
  AArray array;
  array[3] = AArray::Value("foo"); // elements 0-2 are set to null
  array["It's just another quote"] = AArray::Value(3.426);
  array[2][3][4] = AArray::Value(true);
  AArray array2(array); // deep copy