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--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
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--                     G N A T . B U B B L E _ S O R T                      --
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--  Sort Utility (Using Bubblesort Algorithm)

--  This package provides a bubblesort routine that works with access to
--  subprogram parameters, so that it can be used with different types with
--  shared sorting code.

--  See also GNAT.Bubble_Sort_G and GNAT.Bubble_Sort_A. These are older
--  versions of this routine. In some cases GNAT.Bubble_Sort_G may be a
--  little faster than GNAT.Bubble_Sort, at the expense of generic code
--  duplication and a less convenient interface. The generic version also
--  has the advantage of being Pure, while this unit can only be Preelaborate.

package GNAT.Bubble_Sort is
   pragma Pure;

   --  The data to be sorted is assumed to be indexed by integer values from
   --  1 to N, where N is the number of items to be sorted.

   type Xchg_Procedure is access procedure (Op1, Op2 : Natural);
   --  A pointer to a procedure that exchanges the two data items whose
   --  index values are Op1 and Op2.

   type Lt_Function is access function (Op1, Op2 : Natural) return Boolean;
   --  A pointer to a function that compares two items and returns True if
   --  the item with index value Op1 is less than the item with Index value
   --  Op2, and False if the Op1 item is greater than or equal to the Op2
   --  item.

   procedure Sort (N : Natural; Xchg : Xchg_Procedure; Lt : Lt_Function);
   --  This procedures sorts items in the range from 1 to N into ascending
   --  order making calls to Lt to do required comparisons, and calls to
   --  Xchg to exchange items. The sort is stable, that is the order of
   --  equal items in the input is preserved.

end GNAT.Bubble_Sort;