-- FC70B00.A
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-- FC70B00.A
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--
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--
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-- Grant of Unlimited Rights
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-- Grant of Unlimited Rights
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--
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--
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-- Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,
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-- Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,
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-- F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained
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-- F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained
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-- unlimited rights in the software and documentation contained herein.
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-- unlimited rights in the software and documentation contained herein.
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-- Unlimited rights are defined in DFAR 252.227-7013(a)(19). By making
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-- Unlimited rights are defined in DFAR 252.227-7013(a)(19). By making
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-- this public release, the Government intends to confer upon all
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-- this public release, the Government intends to confer upon all
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-- recipients unlimited rights equal to those held by the Government.
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-- recipients unlimited rights equal to those held by the Government.
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-- These rights include rights to use, duplicate, release or disclose the
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-- These rights include rights to use, duplicate, release or disclose the
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-- released technical data and computer software in whole or in part, in
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-- released technical data and computer software in whole or in part, in
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-- any manner and for any purpose whatsoever, and to have or permit others
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-- any manner and for any purpose whatsoever, and to have or permit others
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-- to do so.
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-- to do so.
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--
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--
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-- DISCLAIMER
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-- DISCLAIMER
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--
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--
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-- ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR
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-- ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR
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-- DISCLOSED ARE AS IS. THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED
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-- DISCLOSED ARE AS IS. THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED
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-- WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE
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-- WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE
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-- SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE
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-- SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE
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-- OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
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-- OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
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-- PARTICULAR PURPOSE OF SAID MATERIAL.
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-- PARTICULAR PURPOSE OF SAID MATERIAL.
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--*
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--*
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--
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--
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-- FOUNDATION DESCRIPTION:
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-- FOUNDATION DESCRIPTION:
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-- This foundation defines a generic list abstraction. List elements can
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-- This foundation defines a generic list abstraction. List elements can
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-- be of any (nonlimited) type. Lists are implemented as singly linked
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-- be of any (nonlimited) type. Lists are implemented as singly linked
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-- lists. Access to list elements is sequential. For each list, pointers
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-- lists. Access to list elements is sequential. For each list, pointers
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-- are maintained to the first and last elements in the list, as well as
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-- are maintained to the first and last elements in the list, as well as
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-- the next element to be accessed.
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-- the next element to be accessed.
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--
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--
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-- CHANGE HISTORY:
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-- CHANGE HISTORY:
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-- 06 Dec 94 SAIC ACVC 2.0
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-- 06 Dec 94 SAIC ACVC 2.0
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--
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--
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--!
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--!
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generic -- List abstraction.
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generic -- List abstraction.
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type Element_Type is private; -- List elems can be of any nonlimited type.
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type Element_Type is private; -- List elems can be of any nonlimited type.
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package FC70B00 is
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package FC70B00 is
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type List_Type is limited private;
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type List_Type is limited private;
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-- Return true if current element is last in the list.
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-- Return true if current element is last in the list.
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function End_Of_List (L : List_Type) return Boolean;
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function End_Of_List (L : List_Type) return Boolean;
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-- Read current element value; do NOT advance "current" pointer.
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-- Read current element value; do NOT advance "current" pointer.
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procedure View_Element (L : in List_Type; E : out Element_Type);
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procedure View_Element (L : in List_Type; E : out Element_Type);
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-- Read from current element and advance "current" pointer.
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-- Read from current element and advance "current" pointer.
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procedure Read_Element (L : in out List_Type; E : out Element_Type);
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procedure Read_Element (L : in out List_Type; E : out Element_Type);
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-- Write to current element and advance "current" pointer.
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-- Write to current element and advance "current" pointer.
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procedure Write_Element (L : in out List_Type; E : in Element_Type);
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procedure Write_Element (L : in out List_Type; E : in Element_Type);
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-- Add element to end of list.
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-- Add element to end of list.
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procedure Add_Element (L : in out List_Type; E : in Element_Type);
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procedure Add_Element (L : in out List_Type; E : in Element_Type);
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-- Set "current" pointer to first list element.
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-- Set "current" pointer to first list element.
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procedure Reset (L : in out List_Type);
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procedure Reset (L : in out List_Type);
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private
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private
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type Node_Type;
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type Node_Type;
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type Node_Pointer is access Node_Type;
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type Node_Pointer is access Node_Type;
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type Node_Type is record
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type Node_Type is record
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Item : Element_Type;
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Item : Element_Type;
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Next : Node_Pointer;
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Next : Node_Pointer;
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end record;
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end record;
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type List_Type is record
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type List_Type is record
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First : Node_Pointer;
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First : Node_Pointer;
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Current : Node_Pointer;
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Current : Node_Pointer;
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Last : Node_Pointer;
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Last : Node_Pointer;
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end record;
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end record;
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end FC70B00;
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end FC70B00;
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--==================================================================--
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--==================================================================--
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package body FC70B00 is
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package body FC70B00 is
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function End_Of_List (L : List_Type) return Boolean is
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function End_Of_List (L : List_Type) return Boolean is
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begin
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begin
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return (L.Current = null);
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return (L.Current = null);
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end End_Of_List;
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end End_Of_List;
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procedure View_Element (L : in List_Type; E : out Element_Type) is
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procedure View_Element (L : in List_Type; E : out Element_Type) is
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begin
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begin
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-- ... Error-checking code omitted for brevity.
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-- ... Error-checking code omitted for brevity.
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E := L.Current.Item; -- Retrieve current element.
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E := L.Current.Item; -- Retrieve current element.
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end View_Element;
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end View_Element;
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procedure Read_Element (L : in out List_Type; E : out Element_Type) is
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procedure Read_Element (L : in out List_Type; E : out Element_Type) is
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begin
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begin
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-- ... Error-checking code omitted for brevity.
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-- ... Error-checking code omitted for brevity.
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E := L.Current.Item; -- Retrieve current element.
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E := L.Current.Item; -- Retrieve current element.
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L.Current := L.Current.Next; -- Advance "current" pointer.
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L.Current := L.Current.Next; -- Advance "current" pointer.
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end Read_Element;
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end Read_Element;
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procedure Write_Element (L : in out List_Type; E : in Element_Type) is
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procedure Write_Element (L : in out List_Type; E : in Element_Type) is
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begin
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begin
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-- ... Error-checking code omitted for brevity.
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-- ... Error-checking code omitted for brevity.
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L.Current.Item := E; -- Write to current element.
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L.Current.Item := E; -- Write to current element.
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L.Current := L.Current.Next; -- Advance "current" pointer.
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L.Current := L.Current.Next; -- Advance "current" pointer.
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end Write_Element;
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end Write_Element;
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procedure Add_Element (L : in out List_Type; E : in Element_Type) is
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procedure Add_Element (L : in out List_Type; E : in Element_Type) is
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New_Node : Node_Pointer := new Node_Type'(E, null);
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New_Node : Node_Pointer := new Node_Type'(E, null);
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begin
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begin
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if L.First = null then -- No elements in list, so add new
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if L.First = null then -- No elements in list, so add new
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L.First := New_Node; -- element at beginning of list.
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L.First := New_Node; -- element at beginning of list.
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else
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else
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L.Last.Next := New_Node; -- Add new element at end of list.
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L.Last.Next := New_Node; -- Add new element at end of list.
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end if;
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end if;
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L.Last := New_Node; -- Set last-in-list pointer.
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L.Last := New_Node; -- Set last-in-list pointer.
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end Add_Element;
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end Add_Element;
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procedure Reset (L : in out List_Type) is
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procedure Reset (L : in out List_Type) is
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begin
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begin
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L.Current := L.First; -- Set "current" pointer to first
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L.Current := L.First; -- Set "current" pointer to first
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end Reset; -- list element.
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end Reset; -- list element.
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end FC70B00;
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end FC70B00;
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