projects / thirdparty / gcc.git / blame
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1 | ------------------------------------------------------------------------------ |
| 2 | -- -- | |
| 3084fecd | 3 | -- GNAT RUN-TIME COMPONENTS -- |
| cacbc350 | 4 | -- -- |
| fbf5a39b | 5 | -- G N A T . H E A P _ S O R T -- |
| cacbc350 RK |
6 | -- -- |
| 7 | -- S p e c -- | |
| 8 | -- -- | |
| 4b490c1e | 9 | -- Copyright (C) 1995-2020, AdaCore -- |
| cacbc350 RK |
10 | -- -- |
| 11 | -- GNAT is free software; you can redistribute it and/or modify it under -- | |
| 12 | -- terms of the GNU General Public License as published by the Free Soft- -- | |
| 607d0635 | 13 | -- ware Foundation; either version 3, or (at your option) any later ver- -- |
| cacbc350 RK |
14 | -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- |
| 15 | -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- | |
| 607d0635 AC |
16 | -- or FITNESS FOR A PARTICULAR PURPOSE. -- |
| 17 | -- -- | |
| 18 | -- As a special exception under Section 7 of GPL version 3, you are granted -- | |
| 19 | -- additional permissions described in the GCC Runtime Library Exception, -- | |
| 20 | -- version 3.1, as published by the Free Software Foundation. -- | |
| 21 | -- -- | |
| 22 | -- You should have received a copy of the GNU General Public License and -- | |
| 23 | -- a copy of the GCC Runtime Library Exception along with this program; -- | |
| 24 | -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- | |
| 25 | -- <http://www.gnu.org/licenses/>. -- | |
| cacbc350 RK |
26 | -- -- |
| 27 | -- GNAT was originally developed by the GNAT team at New York University. -- | |
| 71ff80dc | 28 | -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
| cacbc350 RK |
29 | -- -- |
| 30 | ------------------------------------------------------------------------------ | |
| 31 | ||
| fbf5a39b | 32 | -- Sort utility (Using Heapsort Algorithm) |
| cacbc350 | 33 | |
| fbf5a39b AC |
34 | -- This package provides a heapsort routine that works with access to |
| 35 | -- subprogram parameters, so that it can be used with different types with | |
| 36 | -- shared sorting code. | |
| cacbc350 | 37 | |
| fbf5a39b AC |
38 | -- This heapsort algorithm uses approximately N*log(N) compares in the |
| 39 | -- worst case and is in place with no additional storage required. See | |
| 40 | -- the body for exact details of the algorithm used. | |
| cacbc350 | 41 | |
| 5ec0b2e5 AC |
42 | -- See also GNAT.Heap_Sort_G which is a generic version that will be faster |
| 43 | -- since the overhead of the indirect calls is avoided, at the expense of | |
| ac38d4af | 44 | -- generic code duplication and less convenient interface. |
| 5ec0b2e5 AC |
45 | |
| 46 | -- Note: GNAT.Heap_Sort replaces and obsoletes GNAT.Heap_Sort_A, which is | |
| 47 | -- retained in the GNAT library for backwards compatibility. | |
| 48 | ||
| fbf5a39b | 49 | package GNAT.Heap_Sort is |
| a2fd0ecb | 50 | pragma Pure; |
| cacbc350 | 51 | |
| fbf5a39b AC |
52 | -- The data to be sorted is assumed to be indexed by integer values |
| 53 | -- from 1 to N, where N is the number of items to be sorted. | |
| cacbc350 | 54 | |
| fbf5a39b AC |
55 | type Xchg_Procedure is access procedure (Op1, Op2 : Natural); |
| 56 | -- A pointer to a procedure that exchanges the two data items whose | |
| 57 | -- index values are Op1 and Op2. | |
| cacbc350 | 58 | |
| fbf5a39b AC |
59 | type Lt_Function is access function (Op1, Op2 : Natural) return Boolean; |
| 60 | -- A pointer to a function that compares two items and returns True if | |
| 61 | -- the item with index value Op1 is less than the item with Index value | |
| 62 | -- Op2, and False if the Op1 item is greater than the Op2 item. If | |
| 63 | -- the items are equal, then it does not matter if True or False is | |
| 64 | -- returned (but it is slightly more efficient to return False). | |
| cacbc350 | 65 | |
| fbf5a39b AC |
66 | procedure Sort (N : Natural; Xchg : Xchg_Procedure; Lt : Lt_Function); |
| 67 | -- This procedures sorts items in the range from 1 to N into ascending | |
| 68 | -- order making calls to Lt to do required comparisons, and calls to | |
| 69 | -- Xchg to exchange items. The sort is not stable, that is the order | |
| 70 | -- of equal items in the input data set is not preserved. | |
| 71 | ||
| 72 | end GNAT.Heap_Sort; |