48 lines
997 B
C#
48 lines
997 B
C#
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using System;
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using System.Collections.Generic;
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#if !NET_3_5 && !NET_4_0
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namespace System {
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delegate TResult Func<T, TResult> (T t);
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}
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namespace System.Runtime.CompilerServices {
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[AttributeUsage (AttributeTargets.Method | AttributeTargets.Class | AttributeTargets.Assembly)]
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sealed class ExtensionAttribute : Attribute {
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}
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}
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namespace System.Linq {
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static class Enumerable {
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public static IEnumerable<TRet> Select<TItem, TRet> (this IEnumerable<TItem> self, Func<TItem, TRet> selector)
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{
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foreach (var item in self)
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yield return selector (item);
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}
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public static IEnumerable<T> Where<T> (this IEnumerable<T> self, Func<T, bool> predicate)
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{
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foreach (var item in self)
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if (predicate (item))
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yield return item;
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}
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public static T First<T> (this IEnumerable<T> self)
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{
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using (var enumerator = self.GetEnumerator ()) {
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if (!enumerator.MoveNext ())
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throw new InvalidOperationException ();
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return enumerator.Current;
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}
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}
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}
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}
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#endif
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