gistfile1.txt

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--  This source code is subject to the BSD license, see the LICENCE file in the root of this directory.
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--  Maths.Stacks
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with Ada.Containers.Indefinite_Vectors;
--  with Maths.Matrix4s;

generic
   type Element_Type is private;
   with function "=" (Left, Right : Element_Type)
      return Boolean is <>;
package Maths.Stacks is
   type Reference (Matrix : not null access Element_Type) is limited private with
     Implicit_Dereference => Matrix;

   type Stack is private;

   --  procedure Push (Self : in out Stack_Vector.Stack; New_Top : Matrix4s.Matrix4);
   --  function Pop (Self : Stack_Vector.Stack) return Matrix4s.Matrix4;
   function Top (Self : Stack) return Reference; -- Holder? Reference?
private
   --  package M4 renames Maths.Matrix4s;

   --  subtype Matrix is M4.Matrix4 (M4.Components);

   type Reference (Matrix : not null access Element_Type) is limited null record;

   package Stack_Vector is new Ada.Containers.Indefinite_Vectors
     (Index_Type   => Natural,
      Element_Type => Element_Type,
      "="          => "=");
      --  Element_Type => Matrix,
      --  "="          => M4."=");

   type Stack is new Stack_Vector.Vector with null record;
end Maths.Stacks;

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--  This source code is subject to the BSD license, see the LICENCE file in the root of this directory.
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package body Maths.Stacks is
   --  procedure Push (Self : in out Stack_Vector.Stack; New_Top : Matrix4s.Matrix4);
   --  function Pop (Self : Stack_Vector.Stack) return Matrix4s.Matrix4;

   function Top (Self : Stack) return Reference is
   begin
      return Reference'(Matrix => Self.Reference (Self.First_Index).Element);
      --  return R : Reference (Matrix => Self.Reference (Self.First_Index).Element) do
      --     null;
      --  end return;
   end Top;
end Maths.Stacks;

maths-stacks.adb:10:07: error: access discriminant in return object would be a dangling reference
maths-stacks.adb:10:35: error: actual for "Container" must be a variable