-- ****************************************************************************
-- Programmer Name : S. Phillips
-- Program Name : Linked List
-- Revision Number : Rev 1.0
-- Date Created : February 20, 1990
-- Package Description : This generic package implements linked lists.  The package ex-
-- ports all logical operations for these lists as well as a test for list member-
-- ship, a function to return the size of a list.  Procedures for building,
-- and deleting lists are provided as well as methods for stepping
-- through each list.  The generic is instantiated on the element type that the
-- set will be made up of.
-- ****************************************************************************

generic
    type Element is private;
   
package Linked_List is
    type list is limited private;

    -- This procedure adds a member to a list
    procedure Add_Member (X : in out list; A_Member : Element);

    -- This procedure tests for list membership
    procedure Is_Member
                 (X : in out list; A_Member : Element; Answer : out Boolean);

    -- This function returns the size of the list input
    function list_Size (X : in list) return Integer;

    -- This procedure will position a 'cursor' at the first element
    -- of a list in preparation for walking through the entire list
    procedure Rewind (X : in out list);

    -- This procedure returns the element currently being 'pointed to'
    -- by the 'cursor'
    procedure Current_Member (X : in list; A_Member : out Element; null_member : in out boolean);

    -- This procedure bumps the 'cursor' to the next element in the
    -- list and returns this next element in a_member.
    procedure Next_Member (X : in out list; A_Member : out Element; end_of_list : in out boolean);

    -- Function to return whether or not the 'cursor' has reached the
    -- last element of the list
    function Done (X : in list) return Boolean;

    -- Procedure to remove all elements from a list
    procedure Make_Empty (X : in out list);

    -- Procedure which releases all storage associated with a list
    procedure Release (X : in out list);

private
    type Member;
    type Link is access Member;

    type Member is
        record
            Bod : Element;
            Chain : Link := null;
        end record;

    type list is
        record
            Size : Integer := 0;
            Current_Position, Head, Tail : Link := null;
        end record;
end Linked_list;