Stable Sort IEnumerable - CSharp System.Collections.Generic

CSharp examples for System.Collections.Generic:IEnumerable

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Description

Stable Sort IEnumerable

Demo Code


using System.Collections.Generic;
using System.Collections;

public class Main{
        internal static IEnumerable<T> StableSort<T>(IEnumerable<T> items, IComparer<T> comparer)
        {/*from  w  w w. j av a 2  s.c  o m*/
#if NET35
            // LINQ's OrderBy is guaranteed to be a stable sort.
            return items.OrderBy(x => x, comparer);
#else

            // otherwise, tag each item with the index and sort the wrappers.
            // if we're given a collection (and we always are), use its count
            // to prevent unnecessary array copies.
            var itemCollection = items as ICollection<T>;
            var taggedItems = itemCollection == null
                ? new List<IndexTaggedItem<T>>()
                : new List<IndexTaggedItem<T>>(itemCollection.Count);

            int index = 0;
            foreach (var item in items)
            {
                taggedItems.Add(new IndexTaggedItem<T>(item, index++));
            }

            taggedItems.Sort(new IndexAwareComparer<T>(comparer));

            var sorted = new List<T>(taggedItems.Count);
            foreach (var taggedItem in taggedItems)
            {
                sorted.Add(taggedItem.Item);
            }

            return sorted;
#endif
        }
        internal static IEnumerable<T> StableSort<T>(IEnumerable<T> items)
        {
            return StableSort(items, Comparer<T>.Default);
        }
}

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