gcc/testsuite/ada/acats/support/fc70b00.a

   1 -- FC70B00.A
   2 --
   3 --                             Grant of Unlimited Rights
   4 --
   5 --     Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,
   6 --     F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained
   7 --     unlimited rights in the software and documentation contained herein.
   8 --     Unlimited rights are defined in DFAR 252.227-7013(a)(19).  By making
   9 --     this public release, the Government intends to confer upon all
  10 --     recipients unlimited rights  equal to those held by the Government.
  11 --     These rights include rights to use, duplicate, release or disclose the
  12 --     released technical data and computer software in whole or in part, in
  13 --     any manner and for any purpose whatsoever, and to have or permit others
  14 --     to do so.
  15 --
  16 --                                    DISCLAIMER
  17 --
  18 --     ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR
  19 --     DISCLOSED ARE AS IS.  THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED
  20 --     WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE
  21 --     SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE
  22 --     OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
  23 --     PARTICULAR PURPOSE OF SAID MATERIAL.
  24 --*
  25 --
  26 -- FOUNDATION DESCRIPTION:
  27 --      This foundation defines a generic list abstraction. List elements can
  28 --      be of any (nonlimited) type. Lists are implemented as singly linked
  29 --      lists. Access to list elements is sequential. For each list, pointers
  30 --      are maintained to the first and last elements in the list, as well as
  31 --      the next element to be accessed.
  32 --
  33 -- CHANGE HISTORY:
  34 --      06 Dec 94   SAIC    ACVC 2.0
  35 --
  36 --!
  37
  38 generic                           -- List abstraction.
  39    type Element_Type is private;  -- List elems can be of any nonlimited type.
  40 package FC70B00 is
  41
  42    type List_Type is limited private;
  43
  44    -- Return true if current element is last in the list.
  45    function End_Of_List (L : List_Type) return Boolean;
  46
  47    -- Read current element value; do NOT advance "current" pointer.
  48    procedure View_Element (L : in List_Type; E : out Element_Type);
  49
  50    -- Read from current element and advance "current" pointer.
  51    procedure Read_Element (L : in out List_Type; E : out Element_Type);
  52
  53    -- Write to current element and advance "current" pointer.
  54    procedure Write_Element (L : in out List_Type; E : in Element_Type);
  55
  56    -- Add element to end of list.
  57    procedure Add_Element (L : in out List_Type; E : in Element_Type);
  58
  59    -- Set "current" pointer to first list element.
  60    procedure Reset (L : in out List_Type);
  61
  62 private
  63
  64    type Node_Type;
  65    type Node_Pointer is access Node_Type;
  66
  67    type Node_Type is record
  68       Item : Element_Type;
  69       Next : Node_Pointer;
  70    end record;
  71
  72    type List_Type is record
  73       First   : Node_Pointer;
  74       Current : Node_Pointer;
  75       Last    : Node_Pointer;
  76    end record;
  77
  78 end FC70B00;
  79
  80
  81      --==================================================================--
  82
  83
  84 package body FC70B00 is
  85
  86    function End_Of_List (L : List_Type) return Boolean is
  87    begin
  88       return (L.Current = null);
  89    end End_Of_List;
  90
  91
  92    procedure View_Element (L : in List_Type; E : out Element_Type) is
  93    begin
  94       -- ... Error-checking code omitted for brevity.
  95       E := L.Current.Item;               -- Retrieve current element.
  96    end View_Element;
  97
  98
  99    procedure Read_Element (L : in out List_Type; E : out Element_Type) is
 100    begin
 101       -- ... Error-checking code omitted for brevity.
 102       E         := L.Current.Item;       -- Retrieve current element.
 103       L.Current := L.Current.Next;       -- Advance "current" pointer.
 104    end Read_Element;
 105
 106
 107    procedure Write_Element (L : in out List_Type; E : in Element_Type) is
 108    begin
 109       -- ... Error-checking code omitted for brevity.
 110       L.Current.Item := E;               -- Write to current element.
 111       L.Current      := L.Current.Next;  -- Advance "current" pointer.
 112    end Write_Element;
 113
 114
 115    procedure Add_Element (L : in out List_Type; E : in Element_Type) is
 116       New_Node : Node_Pointer := new Node_Type'(E, null);
 117    begin
 118       if L.First = null then             -- No elements in list, so add new
 119          L.First := New_Node;            -- element at beginning of list.
 120       else
 121          L.Last.Next := New_Node;        -- Add new element at end of list.
 122       end if;
 123       L.Last := New_Node;                -- Set last-in-list pointer.
 124    end Add_Element;
 125
 126
 127    procedure Reset (L : in out List_Type) is
 128    begin
 129       L.Current := L.First;              -- Set "current" pointer to first
 130    end Reset;                            -- list element.
 131
 132
 133 end FC70B00;