------------------------------------------------------------------------------ -- -- -- GNAT RUNTIME COMPONENTS -- -- -- -- G N A T . H E A P _ S O R T -- -- -- -- S p e c -- -- -- -- Copyright (C) 1995-2002 Ada Core Technologies, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 2, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- -- MA 02111-1307, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- Sort utility (Using Heapsort Algorithm) -- This package provides a heapsort routine that works with access to -- subprogram parameters, so that it can be used with different types with -- shared sorting code. -- See also GNAT.Heap_Sort_G and GNAT.Heap_Sort_A. These are older versions -- of this routine. In some cases GNAT.Heap_Sort_G may be a little faster -- than GNAT.Heap_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. -- This heapsort algorithm uses approximately N*log(N) compares in the -- worst case and is in place with no additional storage required. See -- the body for exact details of the algorithm used. package GNAT.Heap_Sort is pragma Preelaborate (Heap_Sort); -- 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 the Op2 item. If -- the items are equal, then it does not matter if True or False is -- returned (but it is slightly more efficient to return False). 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 not stable, that is the order -- of equal items in the input data set is not preserved. end GNAT.Heap_Sort;