-- Item :      Generic Contingous List Package Specification
-- Reference : Data Structures and Program Design, Pascal, p 198
-- Author :    Paul Stachour, stachour@winternet.com
-- Version :   1.0, 1999/Jan/28
-- For :       ICS340, Winter 199, Metro State, Minnesota
-- Style :     Ada95, in an ada style, to show type paramaterization
-- Protection: Written 1999,This code is available to the public

generic
  Max_Size   : Natural := 100;  -- Maximum size of the list
  --type         Key_type is (<>);-- Any discrete type with "<" defined.
  type         List_Entry is private;-- A record containing necessary data
  --with function "<"(Left, Right: Key_Type) return Boolean;
package adg_cl is 
-- This file provides the declaration of a contiguous keyed list package
-- with the part common to all types of list entries.
-- It requires that type List_Entry and Max_Size be provided when this 
-- specification is instantaited, and it be "with'ed" as appropriate.
-- Sample instantiation:
--   
subtype Position   is Natural range 1..Max_Size;
subtype List_Count is Natural range 0..Max_Size;
--type CL_Keys is array(position) of Key_Type;
type CL_Data is array(position) of List_Entry;

-- This would usually be private, but is left public so it meshes
-- with other routines from the book which do not enforce privacy.

type List is record
  --Keys: Cl_Keys;
  Data: Cl_Data;
  Count: List_Count;
end record;


type Process_List_Entry is access procedure(LE: in out List_Entry);

-- Note that the word "list" has been left in the name of the
-- subprograms, thought this is not the usual Ada style.
-- The Ada style is without the name of the entity.
-- This style with the entity name is necessary in languages that
-- do not support name overloading, to prevent name clashes.

procedure CreateList(L: in out List);
-- Pre:   None.
-- Post: The list L has been created and is initialized to be empty.


procedure ClearList(L: in out List);
-- Pre:   The list L has been created.
-- Post: All entries of the list L have been deleted.


function ListEmpty(L: in List) return Boolean;
-- Pre:   The list L has been created.
-- Post: The function returns true if the list L is empty, false otherwise.

 
function ListFull(L: List) return Boolean;
-- Pre:   The list L has been created.
-- Post: The function returns true if the list is full, false otherwise.

 
function ListSize(L: List) return List_Count;
-- Pre:   The list L has been created.
-- Post: The function returns the number of entries in list L.

 
procedure InsertList(P: Position; LE: List_Entry; L: in out List);
-- Pre:  The list L has been created, L is not full, x is a valid list
-- entry, and 1 <= p <= n + 1, where n is the number of entries in
-- L.
-- Post: x has been inserted into position p in L; the entry formerly in
-- position p (provided p <= n) and all later entries have their
-- position numbers increased by 1.

 
procedure DeleteList(P: Position; LE: out List_Entry; L: in out List);
-- Pre:  The list L has been created, L is not empty,
-- and 1 <= p <= n, where n is the number of entries in L.
-- Post: The entry in position p of L has been returned as x and deleted
-- from L; the entries in all later positions (provided
-- p < n) have their position numbers decreased by 1.

 
procedure RetrieveList(P: Position; LE: out List_Entry; L: in out list);
-- Pre:  The list L has been created, L is not empty,
-- and 1 <= p <= n, where n is the number of entries in L.
-- Post: The entry in position p of L has been returned as x.  L remains
-- unchanged.


procedure ReplaceList(p: position; LE: List_Entry; L: in out List);
-- Pre:  The list L has been created, L is not empty, x is a valid list
-- entry, and 1 <= p <= n, where n is the number of entries in L.
-- Post: The entry in position p of L has been replaced by x.  The other
-- entries of L remain unchanged.

 
procedure TraverseList(L: in out list; Visit: Process_List_Entry);
-- Pre:   The list L has been created.
-- Post: The action specified by the procedure Visit has been 
-- performed on every entry of the list L, beginning at the first
-- entry and doing each in turn.
-- Uses: RetrieveList, ReplaceList.

end adg_cl;