Assignment #6, COP-3337

A dictionary stores ordered pairs containing a key and value. Your assignment is to implement a template class that supports the dictionary operations. The class interface looks as follows:

template <class KeyType, class ValueType>
class Dictionary
{
  public:
    // Constructors

    // Destructors

    // Accessors

    // Mutators

  private:
    // Copy constructor

    // Data members
    Vector<KeyType>   TheKeys;
    Vector<ValueType> TheValues;
    int               NumberOfItems;
    const ValueType   ItemNotFound;
};

Class Specifications

The class will be templated with an arbitary KeyType and an arbitrary ValueType. Clearly state in a comment preamble any conditions that must be satisfied by the template types. One of the requirements will be that both template types must have zero-parameter constructors. You must also be extremely careful to use correct parameter passing and return mechanisms, and use const member functions when appropriate.

Data Members

The data members are an int that specifies the number of elements in the dictionary, a ValueType object named ItemNotFound, and parallel vectors that store the key and corresponding values. For 5 points extra credit, define a struct that stores a pair, with appropriate constructors, and consolidate the two vectors into one.

Constructors and Destructor

The constructor will be invoked with a parameter that specifies the value that should be returned when a Lookup fails; it uses this parameter to set ItemNotFound. Disable the copy constructor. Take a reasonable course of action for the destructor, and comment what you have done. The initial size of both vectors is 5.

Accessors

Provide a member function named Lookup that takes as parameter an object of type KeyType and returns the corresponding object of type ValueType that is found in the dictionary. If no match is found, return ItemNotFound.

Provide a member function named Size that returns the current number of items in the dictionary. This value is precisely NumberOfItems.

Mutators

Provide a member function named SetValue that takes two parameters: a KeyType and a ValueType. This pair is added to the dictionary. If the KeyType that is passed to SetValue is already in the dictionary, then the corresponding ValueType is replaced by the new value. SetValue may require an array expansion.

Provide a member function named RemoveValue that takes a KeyType as a parameter and removes both it and the corresponding ValueType from the dictionary. The simplest way to do this is to find out where in the array the removed items are, and then overwrite them with the last item in the vector(s). After that is done, decrement NumberOfItems. Remove Value returns 1 if the remove succeeded and 0 if it failed (which would be the case if the item was not found).

Testing The Class

I will provide a data file that will consist of two strings per line (one in English, the other in Spanish). I'll also ask you to look up some English words, and return the corresponding Spanish word. Your program should prompt for a name of a file, read it line by line assuming two strings per line, inserting entries into the dictionary, and then prompt the user to enter words that will be translated and output. The dictionary would be instantiated in the following manner:

// Various #includes

int
main( )
{
    Dictionary<String,String> MyDictionary( "" );

    ...
}

You should test the RemoveValue member separately and make sure it works.

Separate Compilation Rules

You must do everything by the book: create a Dictionary.h, Dictionary.cpp, and a program6.cpp. Provide a Makefile. you may not using the #include statement to include .cpp files. NOTE: A major problem with other compilers is that they do not correctly handle separate compilation of templates. You might have development problems if you use Borland or Visual C++ compilers, espcially old versions.

What to Submit

Submit your dictionary class, your test program, and sample output.