Description of the problem

This assignment is to implement an interactive version of the KWIC index system (described in Parnas's On the Criteria To Be Used in Decomposing Systems into Modules) in the object-oriented paradigm. You will be provided with a partial C++ implementation of the system and asked to identify and make the necessary modifications.

The provided system is simply a line alphabetizer. It interactively inputs a line at a time and upon demand outputs an alphabetized list of the current collection of lines. Here is a transcript of a sample session:

     Add, Print, Quit: a            Add, Print, Quit: a
     > O my son Absalom             > O Absalom
     Add, Print, Quit: a            Add, Print, Quit: p
     > my son my son                        O Absalom
     Add, Print, Quit: a                    O my son Absalom
     > and the king cried                   and the king cried
     Add, Print, Quit: a                    in a loud voice
     > in a loud voice                      my son my son
     Add, Print, Quit: p            Add, Print, Quit: q              
             O my son Absalom
             and the king cried 
             in a loud voice        
             my son my son

Your assignment is to modify the existing code to support the following changes:

• Rather than simply outputting an alphabetic list of all the lines, the Print command should output an alphabetic list of the circular shifts of all the lines. However, shifts (including the nullary shift) which result in a line beginning with a trivial word--a, an, and, the, or the capitalized versions of these words--should be omitted.

  3 different ways of displaying should be supplied. Upon entry of a p at the command line, the system should print another ``menu line":

      Add, Print, Quit: p
      Simple, Aligned, Concordance:

  1. Simple Display: Upon entry of a s at the command line the system should print the alphabetic list of all line shifts, as described above.
  2. Aligned Display: Instead of printing the shifted line, the original sentence is printed, but the word that is at the beginning of the shifted sentence is aligned, and capitalized. For example, the line ``and the king cried" is printed as follows:

         and the king CRIED
              and the KING cried

  3. Concordance Style Display: For each shifted variant of the sentence the original sentence is printed, but the word at the beginning of the shifted variant is abbreviated. The line ``and the king cried" is printed as follows:

         and the king c.
         and the k. cried

• Three commands, Original, Delete and Count , should be added.
  1. Original: Upon entry of an o at the command line, the system should output a list of all lines entered by the user (including lines beginning with trivial words, but not including the circular shifts of lines) in their original order.
  2. Delete: Upon entry of a d at the command line, the system should prompt for a line (much like the Add command). This line should then be deleted from the system.
  3. Count: on entry of a c at the command line, the system should display the number of original lines currently in the system.

Here is a sample session of the new system:

     Add, Print, Original, Delete, Count, Quit: a 
     > and the king cried 
     Add, Print, Original, Delete, Count, Quit: a 
     > in a loud voice
     Add, Print, Original, Delete, Count, Quit: p         
     Simple, Aligned, Concordance: s
             cried and the king
             in a loud voice
             king cried and the
             loud voice in a
             voice in a loud
     Add, Print, Original, Delete, Count, Quit: c         
             2 lines
     Add, Print, Original, Delete, Count, Quit: d
     > and the king cried
     Add, Print, Original, Delete, Count, Quit: c
             1 lines
     Add, Print, Original, Delete, Count, Quit: p
     Simple, Aligned, Concordance: c
             i. a loud voice
             in a l. voice
             in a loud v.
     Add, Print, Original, Delete, Count, Quit: o
             in a loud voice
     Add, Print, Original, Delete, Count, Quit:q