List Class – Testing and Release

I wrote three simple functions to test the list class template (plus three functions to print the contents of the stack).  The first first test function one tests an integer stack.  The second test function defines a simple structure consisting of an integer and a character pointer (string).  I think the parser (the next item to implement) will need a similar structure to hold pointer to the token string from the input line along with the column the token begins (needed to report the location of syntax errors).  The third test function defines a simple enumeration to tests an enumeration stack.

It was during this testing I realized two things.  First that I wanted to pass structure values to push onto the stack or pop from the stack by pointers and not by values (passing the entire structure is not efficient).  A second was that I still wanted to be able to push constants for lists of simple types.  I know this functionality will be needed for the operator stack in the translator.  Therefore, this required two sets of push/pop functions.  The same function names could be used because of C++'s overloading function name feature.  I made the pop by pointer function return the status of whether the stack is empty before a value is popped, in other words, if false is returned, the stack is empty and no value is returned.

I have released this code so far.  The ibcp_0.0.1-src.zip file has been uploaded at Sourceforge IBCP Project.  The .zip file contains the list.h file with the list template class, the test_stack.cpp source file for testing lists (stacks), the VIDE2 project file test_stack.vpj and Makefile.v, both generated by VIDE2.  The project was compiled using Borland C++ 5.5.  (I have yet to get GCC working under MinGW for use with VIDE2 – something I will keep trying as I want to eventually compare the two compilers.)

List Class – Implementation

A class template does not actually generate any code, so all the functions will be written directly in the header (.h) file (which turns out to be necessary to properly instantiate an actual list in the code).  To instantiate a list, the following is used:

    List<int> int_stack;
    List<some_struct> some_struct_stack;

To create a pointer to element within the list, the following is used:

    List<int>::Element *int_element;
    List<some_struct>::Element *some_element;

Note that the struct Element is defined as public to allow this (though the master element pointer is private).   The functions implemented initially are:

    List() – constructor; allocates master element and initializes it
    ~List() – destructor; deallocates any elements in list and master element
    bool empty() – checks if list is currently empty
    Element *top() – get a pointer to element on top of stack.
    push(T value) – pushes  value (by value) on stack
    T pop() - pops value from top of stack (must not be empty)
    push(T *value) – pushes value (by pointer) on stack
    bool pop(T *value) – pops value (by pointer) from top of stack (if not empty)
    first(Element *&element) – sets pointer to first element
    next(Element *&element) – sets pointer to next element
    bool not_end(Element *&element) – check if not end

There are two sets of push and pop functions.  One set works with actual values and is more appropriate for lists of simple types (int, doubles, enums, etc.).  The other set works with pointers to the actual values, which is better for lists of structures, but can be used for simple types also.  I implemented the by value push and pop so that constants could be pushed directly without having to define a variable and set it to the value to push.  I foresee this may be necessary for some of the stacks.  Note that the pop value by value function does not return any status of the list being empty, and therefore the list must not be empty before using this function.  I also added the three functions for use with for statements.  Any additional functions will be added to the list class template as needed.