This is a complete hash table with it's own iterator. It provides a fast and well-tested hash function that can be over-ridden. All features associated with a hash table are implemented.

Note: Template T must provide a method (member function) with the following signature

If a hash function is provided, it must take one parameter: "const char*" and return an "int". The value returned must be a positive integer or zero. Otherwise the underlying array will throw an Exception.

Example <ospace/advanced/examples/Hash3.cpp>


  #include <ospace/advanced/Hash.h>
#include <ospace/std/iostream>

// When STL string is member of a class, such as person in this example,       
//  we simply overload the conversion operator to char* for the class itself.     
//  The STL string is used as is.                                                                          

class person
   {
   public:
      person( );
      person(string, short);
      person(const person&);
      person& operator=(const person&);
      operator const char* (void) const {return name.c_str();}
      short Age(void) {return age;}
      void setAge(short a) {age = a;}
   private:
      string name;
      short age; 
   };

person::person(void) : name() 
   {
   age = 0;
   }

person::person(string n, short a) : name(n) 
   {
   age = a;
   }

person::person(const person& p) : name(p.name) 
   {
   age = p.age;
   }

person& person::operator=(const person& p) 
   {
   if (*this != p) 
      {
      name = p.name;
      age = p.age;
      }
   return *this;
   }

// Inserting multiple copies of an item with same key, in Hash table. Finding
//  number of insertions, and navigating among items with same key.

int main() 
   {
   os_Hash<person> personTable;

   person P("John", 39);
   personTable << P;  // insert in table

   P.setAge(44);
   personTable << P;

   P.setAge(21);
   personTable << P;

   P.setAge(87);
   personTable << P;

   // Last item inserted in table is at top. Get attributes of last item.

   if (personTable.entity("John").Age() == 87)
      cout << "Last person inserted was 87 years old." << endl;
   else 
      cout << "Last person inserted was NOT 87 years old." << endl;

   // Get the number of items with same key.
   int num = personTable.number("John");
   cout << "There are " << num << " persons named John" << endl;

   // Important. Counting begins at 1 (not 0) and proceeds like stack. So,
   //  first person inserted will be at bottom, in this case 4th item.

   person& pr = personTable.Member("John", num);
   cout << "First person named John was " << pr.Age() << " years old." << endl;

   return 0;
   }

Hashtable

Example <ospace/advanced/examples/Hash3.cpp>