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WITH Ada.Text_IO;
WITH Simple_Dates;
PACKAGE Compact IS
------------------------------------------------------------------
--| This package provides data structures and operations for 
--| manipulating a simple "data base" of audio compact discs, each
--| record containing a code number, artist, disc title, category
--| of disc, date of purchase, and price you paid.
--| 
--| The package makes use of resources provided 
--| by the package Simple_Dates.
--|
--| Author: Michael B. Feldman, The George Washington University 
--| Last Modified: March 1997 
------------------------------------------------------------------

  -- constant and type definitions

  NameSize: CONSTANT Positive := 10;
  MaxDiscs: CONSTANT Positive := 25;

  SUBTYPE BarCode   IS Positive RANGE 00001..99999;
  SUBTYPE NameType  IS String(1..NameSize);
  SUBTYPE PriceType IS Float RANGE 0.00 .. 99.99;

  TYPE Categories IS (Jazz, Rock, Classical, Comedy); 

  TYPE Disc IS PRIVATE;

  -- operations

  PROCEDURE Get (Item: OUT Disc);
  -- Pre:  None
  -- Post: Gets a disc record, robustly, from the keyboard 

  PROCEDURE Put (Item: IN Disc);
  -- Pre:  Item is defined
  -- Post: Displays one disc record on the screen

  PROCEDURE DisplayDatabase;
  -- Pre:  The database has at least been cleared
  -- Post: Displays the entire database on the screen

  PROCEDURE ClearDatabase;
  -- Pre:  None
  -- Post: The database behaves as though it is empty

  PROCEDURE ReadDatabase;
  -- Pre:  None
  -- Post: Reads all records from a file into the database

  PROCEDURE WriteDatabase;
  -- Pre:  The database has at least been cleared
  -- Post: Writes all records in the database to a file   

  PROCEDURE FindDisc(Code: IN BarCode;
            Item: OUT Disc; Success: OUT Boolean);
  -- Pre:  Code is defined
  -- Post: If this disc is already in the database, returns the
  --         disc record and Success is True;
  --         otherwise, Success is False

  PROCEDURE AddDisc (Item: IN Disc; Success: OUT Boolean);
  -- Pre:  Item is defined
  -- Post: If this disc is not already in the database, adds this
  --         disc to the database and Success is True;
  --         otherwise, Success is False

  PROCEDURE DeleteDisc (Code: IN BarCode; Success: OUT Boolean);
  -- Pre:  Tag is defined
  -- Post: If this disc is already in the database, deletes this
  --         disc from the database and Success is True;
  --         otherwise, Success is False

PRIVATE

  TYPE Disc IS RECORD
    CodeNumber:     BarCode;
    Artist:         NameType;
    Title:          NameType;
    Category:       Categories;
    PurchaseDate:   Simple_Dates.Date;
    PurchasePrice:  PriceType;
  END RECORD;

END Compact;