Templates and STL

As we discussed in the lectures, Java has a very structured Collections library. We can develop a similar library for C++ that use STL classes underneath. We will implement some the interfaces (abstract classes with pure virtual functions only), some concrete classes, and some of the helper classes such as iterators.



















The above figure shows a simplified version of the Collections. We will write corresponding templated classes for Collection, Set, List, Queue, which are all abstract classes with all pure virtual functions with no data members. HashSet, ArrayList, and LinkedList are concrete classes. Note that LinkedList uses multiple inheritance. Following table defines the functions for each class

Class Name
Public Function Name
Definition
Collection
This is a templated class with two template parameters like the std::stack class of STL. The

first parameter is the template type E and the second parameter is the STL container that will

do all the work for us.


iterator()
Returns an iterator over the collection







add(E e)
Ensures that this collection contains the specified element







addAll(Collection c)
Adds all of the elements in the specified collection to this





collection

clear()
Removes all of the elements from this collection







contains(E e)
Returns true if this collection contains the specified element.







containsAll(Collection c)
Returns true if this collection contains all of the elements in the





specified collection.

isEmpty()
Returns true if this collection contains no elements.







remove(E e)
Removes a single instance of the specified element from this





collection, if it is present

removeAll(Collection c)
Removes all of this collection's elements that are also contained





in the specified collection

retainAll(Collection c)
Retains only the elements in this collection that are contained in





the specified collection

size()
Returns the number of elements in this collection.



Set
A collection that contains no duplicate elements. There is no order for this collection. In other

words, you don’t have to keep the insertion order of the elements.
List
An ordered collection (also known as a sequence). The user of this interface has precise

control over where in the list each element is inserted.
Queue
Queues order elements in a FIFO (first-in-first-out) manner. There is no random access with

this Collection. Some functions throw exceptions.

add(E e)
Inserts the specified element into this queue

element()
Retrieves, but does not remove, the head of this queue.

offer(E e)
Inserts the specified element into this queue

poll()
Retrieves and removes the head of this queue, or throws if this


queue is empty.
HashSet
Implements Set functions

ArrayList
Implements List functions

LinkedList
Implements both List and Queue functions. Your class does not have to have a linked list to

implement these.

Iterator
hasNext()
Returns true if the iteration has more elements.

next()
Returns the next element in the iteration and advances the


iterator.

remove()
Removes from the underlying collection the last element returned


by this iterator

Your C++ Collections hierarchy should use only STL containers in the concrete classes to implement all the functions. Second parameter of the Collection template can be any of std::vector (default
container), std::list, and std::set.

You will test each function of each concrete class with template parameters of int and string. You will also use the three possible containers with all combinations.

Notes:

    • Define and use your namespace.

    • Do error and range checking for any parameters. Throw exceptions and test them in your client code. Do not forget to define the throw lists for your functions.

    • For each class you will write its own header .h file and .cpp file for the separation of interface and implementation.

    • As expected, you should follow all object-oriented programming principles and all submission rules.

    • You should submit your work to the moodle page.

    • You should submit the header and source code files and sample output results.