-- Item :      Contingous List Package Specification
-- Reference : Data Structures and Program Design, Pascal, p 198
-- Author :    Kruse, recoded by Paul Stachour, stachour@winternet.com
-- Version :   1.0, 1999/Jan/21
-- For :       ICS340, Winter 199, Metro State, Minnesota
-- Style :     Ada95, in a pascalish style, to match the textbook.
-- Protection: Original copyright 1994, Prentice Hall
-- Derivation: Derivation by permission; see Author for details
-- Disclaimer: This routine has not been tested, only translated

package ch6_cl is 
-- This file completes the declaration of a contiguous list package with the
-- part common to all types of list entries.
-- It requires that type listentry and maxlist be redeclared in this
-- specification, and it be "with'ed" as appropriate.
-- This style is taken to be similar to other languages,
-- in Ada one would usually use an instantiated generic or a variant record.

maxlist: constant integer := 10_000;
type listentry is new integer;  -- Should be Natural, Integer for compat.
subtype position is integer range 1..maxlist;
subtype listcount is integer range 0..maxlist;
type cldata is array(position) of listentry;

type list is record
  data: cldata;
  count: listcount;
end record;


type processlistentry is access procedure(LE: in out listentry);

 
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 listcount;
-- Pre:   The list L has been created.
-- Post: The function returns the number of entries in list L.

 
procedure InsertList(p: position; x: listentry; 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; x: out listentry; 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; x: out listentry; 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; x: listentry; 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: processlistentry);
-- 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 ch6_cl;