[SOLVED] COEN79-Lab 3

A sequence class is similar to a bag—both contain a bunch of items, but unlike a bag, the items in a sequence are arranged in an order. In contrast to the bag class, the member functions of a sequence will allow a program to step through the sequence one item at a time. Member functions also permit a program to control precisely where items are inserted and removed within the sequence.

Our sequence is a class that depends on an underlying value_type, and the class also provides a size_type.

Three member functions work together to enforce the in-order retrieval rule:

void start( );

value_type current( ) const; void advance( );

• After activating start, the current function returns the first item
• Each time we call advance, the current function changes so that it returns the next item in the sequence

Provide some additional useful member functions, such as:

1. insert_front: insert a new value at the front of the sequence. This new item should now be the current item.
2. remove_front: remove the value at the front of the sequence. The new front item should now be the current item.
3. attach_back: insert a new value at the back of the sequence. This new item should now be the current item.
4. _end: The last item in the sequence should now be the current item.
5. operator+ and operator+=: These operators should have the precondition that the sum of the sizes of the two sequences being added is smaller than the CAPACITY of a sequence.

Subscript operator:

For a sequence _x, we would like to be able to refer to the individual items using the usual C++ notation for arrays. For example, if _x has three items, then we want to be able to write x[0], x[1], and x[2] to access these three items. This use of the square brackets is called the subscript operator. The subscript operator may be overloaded as a member function, with the prototype shown here as part of the sequence class:

class sequence { public:

… value_type operator [] (size_type index) const; …

As you can see, the operator[] is a member function with one parameter. The parameter is the index of the item that we want to retrieve. The implementation of this member function should check that the index is a valid index (i.e., index is less than the sequence size), and then return the specified item.

For this project, specify, design, and implement this new subscript operator for the sequence.