This section will document any updates applied to the project since original release:

• revision 1: a bug was discovered in the unit test for lsetpos, and by extension, an omission from the unit test for ldisplay (20151027)
  • unit-ldisplay: was not doing a discrete test for the “<ERROR>” output when given an invalid position to display (FIXED)
    • as a result, the number of checks for ldisplay incremented from 30 to 31
  • unit-lsetpos: was displaying “<NULL>” when it really should have been displaying “<ERROR>” (very last test).
    • also added a check for an another invalid position
      • as a result, the number of checks for ldisplay incremented from 13 to 14
  • for those who have already submit, not to worry, you will not be penalized, and you do not need to resubmit

In this project, we take a step up from our singly linked list implementation- just as the singly-linked list was a step up from the individual nodes as an organizing unit for nodes.

So what does this give us? An organizing unit for lists! I'm calling them “ListGroups” or “GroupOfLists”, and we'll also sneak in true linked list functionality, by adding an “after” pointer to the List struct.

We can now organize our lists with this new groupoflists struct (typedef'ed to Group for typing convenience).

#ifndef _GROUP_H
#define _GROUP_H
 
#include "list.h"                        // list relies on node to work
 
struct groupoflists {
    List *first;                         // pointer to first list
    List *last;                          // pointer to last list
};
typedef struct groupoflists Group;       // because we deserve nice things
 
Group *mkgroup(void);                    // create/allocate new Group
Group *rmgroup(Group *);                 // clear/deallocate Group
 
Group *linsert(Group *, List *, List *); // add list before given list
Group *lappend(Group *, List *, List *); // add list after given list
Group *lobtain(Group *, List **);        // obtain/disconnect list from group
 
long int  ldisplay(Group *, long int);   // display entire/aspects of list group
 
long int  lgetpos(Group *, List *);      // retrieve position from given node
List     *lsetpos(Group *, long int);    // seek to indicated node in list
 
#endif

You should notice a striking similarity to the core list functionality (a first and a last pointer– only to Lists, and not Nodes), and the presence of Group manipulation and utility functions (appending, inserting, obtaining, displaying, getting/setting position, creating, and removing a group).

This project will test the level of your abstraction skills– for there isn't that much of a conceptual difference between the list functions and the group functions. The more you understand that, the easier this project will be.

In src/group/, you will find 7 new C files:

• obtain.c - which will house the group lobtain() function (to disconnect lists from a group)
• pos.c - which will handle getting/setting list positions within the group
• mk.c - which will handle creating (allocating) a new group struct
• rm.c - which will handle deallocating (purging) the group
• insert.c - which will handle inserting (linsert()) a new list into the group
• append.c - which will house the group appending function lappend()
• display.c - which will house the group display (ldisplay()) function.

Take a look at the code there. These are the files that contain functions which will be compiled and archived into the group library (libgroup.a) we will be using in this and future projects.

Figure out what is going on, make sure you understand it.

In unit/group/, you will find the unit tests and verify scripts for the functions to be implementated in the group library.

These are complete runnable programs (when compiled, and linked against the group library, which is all handled for you by the Makefile system in place).

Of particular importance, I want you to take a close look at:

• the source code to each of these unit tests
  • the purpose of these programs is to validate the correct functionality of the respective library functions
  • follow the logic
  • make sure you understand what is going on
  • ask questions to get clarification!
• the output from these programs once compiled and ran
  • analyze the output
  • make sure you understand what is going on
  • ask questions to get clarification!

To assist you in verifying a correct implementation, a fully working implementation of the node library, list library (with new modifications), and group library should resemble the following:

Here is what you should get for all the functions completed in the group library:

lab46:~/src/data/sll4$ make check
======================================================
=    Verifying Singly-Linked Group Functionality     =
======================================================
   [mkgroup] Total:   5, Matches:   5, Mismatches:   0
   [rmgroup] Total:   3, Matches:   3, Mismatches:   0
   [linsert] Total:  20, Matches:  20, Mismatches:   0
   [lappend] Total:  20, Matches:  20, Mismatches:   0
   [lobtain] Total:  15, Matches:  15, Mismatches:   0
  [ldisplay] Total:  31, Matches:  31, Mismatches:   0
   [lgetpos] Total:  14, Matches:  14, Mismatches:   0
   [lsetpos] Total:  14, Matches:  14, Mismatches:   0
======================================================
   [RESULTS] Total: 122, Matches: 122, Mismatches:   0
======================================================
lab46:~/src/data/sll4$