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https://github.com/gnustep/libs-base.git
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b9b63476ef
interface that can be used for all sorting tasks in the library. The actual sort algorithms to use are now plugable. Timsort is the new default sorting algorithm, the existing algorithms, shellsort and quicksort, can still be selected using a configure switch. Also implement the new NSComparator (blocks) based sorting and insertion index searching methods for NSMutableArray and NSArray. git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@35573 72102866-910b-0410-8b05-ffd578937521
125 lines
3 KiB
Objective-C
125 lines
3 KiB
Objective-C
/* Implementation of ShellSort for GNUStep
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Copyright (C) 1995-2012 Free Software Foundation, Inc.
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Written by: Richard Frith-Macdonald <rfm@gnu.org>
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Modified by: Niels Grewe <niels.grewe@halbordnung.de>
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Date: September 2012
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This file is part of the GNUstep Base Library.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free
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Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02111 USA.
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*/
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#import "Foundation/NSSortDescriptor.h"
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#import "Foundation/NSArray.h"
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#import "Foundation/NSObjCRuntime.h"
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#import "GSSorting.h"
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#ifndef GS_DISABLE_SHELLSORT
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void
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_GSShellSort(id *objects,
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NSRange sortRange,
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id comparisonEntity,
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GSComparisonType type,
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void *context)
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{
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/* Shell sort algorithm taken from SortingInAction - a NeXT example */
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#define STRIDE_FACTOR 3 // good value for stride factor is not well-understood
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// 3 is a fairly good choice (Sedgewick)
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NSUInteger c;
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NSUInteger d;
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NSUInteger stride = 1;
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BOOL found;
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NSUInteger count = NSMaxRange(sortRange);
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#ifdef GSWARN
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BOOL badComparison = NO;
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#endif
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while (stride <= count)
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{
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stride = stride * STRIDE_FACTOR + 1;
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}
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while (stride > (STRIDE_FACTOR - 1))
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{
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// loop to sort for each value of stride
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stride = stride / STRIDE_FACTOR;
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for (c = (sortRange.location + stride); c < count; c++)
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{
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found = NO;
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if (stride > c)
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{
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break;
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}
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d = c - stride;
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while (!found) /* move to left until correct place */
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{
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id a = objects[d + stride];
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id b = objects[d];
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NSComparisonResult r;
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r = GSCompareUsingDescriptorOrComparator(a, b, comparisonEntity, context);
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if (r < 0)
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{
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#ifdef GSWARN
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if (r != NSOrderedAscending)
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{
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badComparison = YES;
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}
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#endif
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objects[d+stride] = b;
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objects[d] = a;
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if (stride > d)
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{
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break;
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}
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d -= stride; // jump by stride factor
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}
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else
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{
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#ifdef GSWARN
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if (r != NSOrderedDescending && r != NSOrderedSame)
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{
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badComparison = YES;
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}
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#endif
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found = YES;
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}
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}
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}
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}
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#ifdef GSWARN
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if (badComparison == YES)
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{
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NSWarnFLog(@"Detected bad return value from comparison");
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}
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#endif
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}
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@interface GSShellSortPlaceHolder : NSObject
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@end
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@implementation GSShellSortPlaceHolder
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+ (void)load
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{
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_GSSortUnstable = _GSShellSort;
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}
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@end
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#endif
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