// The Dictionary abstract class.  KEComp compares a key
// and an element. EEComp compares two elements.  
template <class Key, class Elem, class KEComp, class EEComp>
class  Dictionary {
public:
  // Reinitialize dictionary
  virtual void clear() = 0;
  // Insert an element.  Return true if insert is
  // successful, false otherwise.
  virtual bool insert(const Elem&) = 0;
  // Remove some element matching Key.  Return true if such
  // exists, false otherwise.  If multiple entries match
  // Key, an arbitrary one is removed.
  virtual bool remove(const Key&, Elem&) = 0;
  // Remove and return an arbitrary element from dictionary.
  // Return true if some element is found, false otherwise.
  virtual bool removeAny(Elem&) = 0;
  // Return a copy of some Elem matching Key.  Return true
  // if such exists, false otherwise.  If multiple elements
  // match Key, return an arbitrary one.
  virtual bool find(const Key&, Elem&) const = 0;
  // Return the number of elements in the dictionary.
  virtual int size() = 0;
};