PC World 1998 October/PCWorld_1998-10_cd.bin/software/prehled/komix/DATA.Z/generic_dictionary.adb

Text File | 1997-10-20 | 3KB | 120 lines

-- generic_dictionary.adb
--
-- Copyright (c) 1996 Cadre Technologies Inc, All Rights Reserved
--
-- This file contains the implementation of a simple, unoptimized, generic
-- dictionary package that is provided without any express or implied
-- warranties and is intended for interim use in order to allow the
-- compilation and linking of the generated Ada code.  This package should
-- ultimately be replaced by a production quality version such as from the
-- compiler vendor's program library.

with Unchecked_Deallocation;
package body Generic_Dictionary is

    procedure Free is new
    Unchecked_Deallocation(Dictionary_Item, Dictionary_Item_Acc);

    -- Add value V with key K to dictionary D
    procedure Add(D : in out Dictionary; K : Key; V : Value) is
    Item : Dictionary_Item_Acc := D.First;
    Last : Dictionary_Item_Acc := null;
    begin
    while Item /= null loop
        if Item.K = K then
        raise Already_Exists;
        end if;
        Last := Item;
        Item := Item.Next;
    end loop;
    Item := new Dictionary_Item;
    if Last = null then
        D.First := Item;
    else
        Last.Next := Item;
    end if;
    Item.K := K;
    Item.V := V;
    Item.Next := null;
    D.Count := D.Count + 1;
    end Add;

    -- Remove value with key K from dictionary D
    procedure Remove(D : in out Dictionary; K : Key) is
    Item : Dictionary_Item_Acc := D.First;
    Last : Dictionary_Item_Acc := null;
    begin
    while Item /= null loop
        if Item.K = K then
        if Last = null then
            D.First := Item.Next;
        else
            Last.Next := Item.Next;
        end if;
        D.Count := D.Count - 1;
        return;
        end if;
        Last := Item;
        Item := Item.Next;
    end loop;
    raise Does_Not_Exist;
    end Remove;

    -- Remove all values from dictionary D
    procedure Remove_All(D : in out Dictionary) is
    Item : Dictionary_Item_Acc := D.First;
    Next : Dictionary_Item_Acc;
    begin
    while Item /= null loop
        Next := Item.Next;
        Free(Item);
        Item := Next;
    end loop;
    D.First := null;
    D.Count := 0;
    end Remove_All;

    -- Return whether or not dictionary D contains value with key K
    function Has(D : Dictionary; K : Key) return Boolean is
    Item : Dictionary_Item_Acc := D.First;
    begin
    while Item /= null loop
        if Item.K = K then
        return True;
        end if;
        Item := Item.Next;
    end loop;
    return False;
    end Has;

    -- Return value for key K from dictionary D
    function Find_Value(D : Dictionary; K : Key) return Value is
    Item : Dictionary_Item_Acc := D.First;
    begin
    while Item /= null loop
        if Item.K = K then
        return Item.V;
        end if;
        Item := Item.Next;
    end loop;
    raise Does_Not_Exist;
    end Find_Value;

    -- Return the number of values in D
    function Count(D : Dictionary) return Natural is
    begin
    return D.Count;
    end Count;

    -- Iterator
    procedure Iterate(D : Dictionary) is
    Item : Dictionary_Item_Acc := D.First;
    begin
    while Item /= null loop
        Process(Item.K, Item.V);
        Item := Item.Next;
    end loop;
    end Iterate;

end Generic_Dictionary;