Dialogs/Extensions.cs
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33 
34 using System;
35 using System.Collections.Generic;
36 using System.Linq;
37 using System.Runtime.Serialization;
38 
39 namespace Microsoft.Bot.Builder.Dialogs.Internals
40 {
41  public static partial class Extensions
42  {
43  public static T MaxBy<T, R>(this IEnumerable<T> items, Func<T, R> selectRank, IComparer<R> comparer = null)
44  {
45  comparer = comparer ?? Comparer<R>.Default;
46 
47  var bestItem = default(T);
48  var bestRank = default(R);
49  using (var item = items.GetEnumerator())
50  {
51  if (item.MoveNext())
52  {
53  bestItem = item.Current;
54  bestRank = selectRank(item.Current);
55  }
56 
57  while (item.MoveNext())
58  {
59  var rank = selectRank(item.Current);
60  var compare = comparer.Compare(rank, bestRank);
61  if (compare > 0)
62  {
63  bestItem = item.Current;
64  bestRank = rank;
65  }
66  }
67  }
68 
69  return bestItem;
70  }
71  }
72 }