54 lines
1.7 KiB
C#
54 lines
1.7 KiB
C#
// ==++==
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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// ==--==
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//============================================================
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//
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// Class: Comparer
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//
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// Purpose: Default IComparer implementation.
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//
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//===========================================================
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namespace System.Collections
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{
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using System;
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using System.Globalization;
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//| <include path='docs/doc[@for="Comparer"]/*' />
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public sealed class Comparer : IComparer
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{
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//| <include path='docs/doc[@for="Comparer.Default"]/*' />
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public static readonly Comparer Default = new Comparer();
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public Comparer() {
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}
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// Compares two Objects by calling CompareTo. If a ==
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// b,0 is returned. If a implements
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// IComparable, a.CompareTo(b) is returned. If a
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// doesn't implement IComparable and b does,
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// -(b.CompareTo(a)) is returned, otherwise an
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// exception is thrown.
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//
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//| <include path='docs/doc[@for="Comparer.Compare"]/*' />
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public int Compare(Object a, Object b) {
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if (a == b) return 0;
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if (a == null) return -1;
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if (b == null) return 1;
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String sa = a as String;
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String sb = b as String;
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if (sa != null && sb != null)
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return CompareInfo.Compare(sa, sb);
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IComparable ia = a as IComparable;
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if (ia != null)
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return ia.CompareTo(b);
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IComparable ib = b as IComparable;
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if (ib != null)
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return -ib.CompareTo(a);
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throw new ArgumentException("Argument_ImplementIComparable");
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}
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}
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}
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