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Adding TryLast extension methods

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This commit is contained in:
Chris Cameron
2017-12-11 21:14:52 -05:00
parent f9997f6d42
commit 8d0042aa19
2 changed files with 84 additions and 1 deletions
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36
ICD.Common.Utils.Tests/Extensions/EnumerableExtensionsTest.cs
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@@ -3,7 +3,6 @@ using ICD.Common.Utils.Extensions;
using NUnit.Framework;
using System.Collections.Generic;
using System.Linq;
using System;
namespace ICD.Common.Utils.Tests.Extensions
{
@@ -62,6 +61,41 @@ namespace ICD.Common.Utils.Tests.Extensions
Assert.AreEqual(true, exists);
}
[TestCase(1)]
public void TryLastTest(int expected)
{
IEnumerable<int> sequence = Enumerable.Empty<int>();
int result;
bool exists = sequence.TryLast(out result);
Assert.AreEqual(0, result);
Assert.AreEqual(false, exists);
sequence = new[] { expected };
exists = sequence.TryLast(out result);
Assert.AreEqual(expected, result);
Assert.AreEqual(true, exists);
}
[TestCase(0)]
[TestCase(1)]
public void TryLastPredicateTest(int expected)
{
IEnumerable<int> sequence = Enumerable.Range(1, 10).Except(expected);
int result;
bool exists = sequence.TryLast(i => i == expected, out result);
Assert.AreEqual(0, result);
Assert.AreEqual(false, exists);
sequence = new[] { expected };
exists = sequence.TryLast(i => i == expected, out result);
Assert.AreEqual(expected, result);
Assert.AreEqual(true, exists);
}
[TestCase(0, 0)]
[TestCase(1, 10)]
public void TryElementAtTest(int index, int expected)

49
ICD.Common.Utils/Extensions/EnumerableExtensions.cs
View File

@@ -94,6 +94,55 @@ namespace ICD.Common.Utils.Extensions
return false;
}
/// <summary>
/// Returns true if there is at least 1 item in the sequence.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="extends"></param>
/// <param name="item">Outputs the last item in the sequence.</param>
/// <returns></returns>
public static bool TryLast<T>(this IEnumerable<T> extends, out T item)
{
if (extends == null)
throw new ArgumentNullException("extends");
return extends.TryLast(i => true, out item);
}
/// <summary>
/// Returns true if there is at least 1 item in the sequence.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="extends"></param>
/// <param name="predicate"></param>
/// <param name="item">Outputs the last item in the sequence.</param>
/// <returns></returns>
public static bool TryLast<T>(this IEnumerable<T> extends, Func<T, bool> predicate, out T item)
{
if (extends == null)
throw new ArgumentNullException("extends");
if (predicate == null)
throw new ArgumentNullException("predicate");
item = default(T);
bool output = false;
using (IEnumerator<T> iterator = extends.GetEnumerator())
{
while (iterator.MoveNext())
{
if (!predicate(iterator.Current))
continue;
item = iterator.Current;
output = true;
}
}
return output;
}
/// <summary>
/// Returns the true if an element with the given index is in the sequence.
/// </summary>