73 lines
4.2 KiB
Ada
73 lines
4.2 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- G N A T . H E A P _ S O R T --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1995-2010, AdaCore --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- Sort utility (Using Heapsort Algorithm)
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-- This package provides a heapsort routine that works with access to
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-- subprogram parameters, so that it can be used with different types with
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-- shared sorting code.
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-- This heapsort algorithm uses approximately N*log(N) compares in the
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-- worst case and is in place with no additional storage required. See
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-- the body for exact details of the algorithm used.
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-- See also GNAT.Heap_Sort_G which is a generic version that will be faster
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-- since the overhead of the indirect calls is avoided, at the expense of
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-- generic code duplication and less convenient interface.
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-- Note: GNAT.Heap_Sort replaces and obsoletes GNAT.Heap_Sort_A, which is
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-- retained in the GNAT library for backwards compatibility.
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package GNAT.Heap_Sort is
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pragma Pure;
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-- The data to be sorted is assumed to be indexed by integer values
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-- from 1 to N, where N is the number of items to be sorted.
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type Xchg_Procedure is access procedure (Op1, Op2 : Natural);
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-- A pointer to a procedure that exchanges the two data items whose
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-- index values are Op1 and Op2.
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type Lt_Function is access function (Op1, Op2 : Natural) return Boolean;
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-- A pointer to a function that compares two items and returns True if
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-- the item with index value Op1 is less than the item with Index value
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-- Op2, and False if the Op1 item is greater than the Op2 item. If
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-- the items are equal, then it does not matter if True or False is
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-- returned (but it is slightly more efficient to return False).
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procedure Sort (N : Natural; Xchg : Xchg_Procedure; Lt : Lt_Function);
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-- This procedures sorts items in the range from 1 to N into ascending
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-- order making calls to Lt to do required comparisons, and calls to
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-- Xchg to exchange items. The sort is not stable, that is the order
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-- of equal items in the input data set is not preserved.
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end GNAT.Heap_Sort;
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