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ArmoryNodeatifaziz
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atifaziz
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Add "SkipLastWhile" extension
This is a squashed merge of PR #1085 that closes #1036. --------- Co-authored-by: Atif Aziz <[email protected]>
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‎MoreLinq.Test/SkipLastWhileTest.cs

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#region License and Terms
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// MoreLINQ - Extensions to LINQ to Objects
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// Copyright (c) 2024 Andy Romero (armorynode). All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#endregion
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namespace MoreLinq.Test
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{
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using System.Collections.Generic;
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using NUnit.Framework;
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[TestFixture]
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public class SkipLastWhileTest
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{
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[Test]
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public void IsLazy()
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{
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_ = new BreakingSequence<object>().SkipLastWhile(BreakingFunc.Of<object, bool>());
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}
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[TestCase(SourceKind.Sequence)]
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[TestCase(SourceKind.BreakingList)]
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[TestCase(SourceKind.BreakingReadOnlyList)]
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public void PredicateNeverFalse(SourceKind sourceKind)
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{
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using var sequence = TestingSequence.Of(0, 1, 2, 3, 4);
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Assert.That(sequence.ToSourceKind(sourceKind).SkipLastWhile(x => x < 5), Is.Empty);
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}
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[TestCase(SourceKind.Sequence)]
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[TestCase(SourceKind.BreakingList)]
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[TestCase(SourceKind.BreakingReadOnlyList)]
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public void PredicateNeverTrue(SourceKind sourceKind)
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{
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using var sequence = TestingSequence.Of(0, 1, 2, 3, 4);
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sequence.ToSourceKind(sourceKind)
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.SkipLastWhile(x => x == 100)
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.AssertSequenceEqual(0, 1, 2, 3, 4);
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}
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[TestCase(SourceKind.Sequence)]
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[TestCase(SourceKind.BreakingList)]
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[TestCase(SourceKind.BreakingReadOnlyList)]
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public void PredicateBecomesTruePartWay(SourceKind sourceKind)
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{
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using var sequence = TestingSequence.Of(0, 1, 2, 3, 4);
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sequence.ToSourceKind(sourceKind)
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.SkipLastWhile(x => x > 2)
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.AssertSequenceEqual(0, 1, 2);
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}
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[TestCase(SourceKind.Sequence)]
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[TestCase(SourceKind.BreakingList)]
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[TestCase(SourceKind.BreakingReadOnlyList)]
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public void NeverEvaluatesPredicateWhenSourceIsEmpty(SourceKind sourceKind)
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{
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using var sequence = TestingSequence.Of<int>();
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Assert.That(sequence.ToSourceKind(sourceKind)
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.SkipLastWhile(BreakingFunc.Of<int, bool>()),
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Is.Empty);
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}
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[TestCase(SourceKind.Sequence)]
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[TestCase(SourceKind.BreakingList)]
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[TestCase(SourceKind.BreakingReadOnlyList)]
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public void UsesCollectionCountAtIterationTime(SourceKind sourceKind)
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{
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var list = new List<int> { 1, 2, 3, 4 };
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var result = list.ToSourceKind(sourceKind).SkipLastWhile(x => x > 2);
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list.Add(5);
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result.AssertSequenceEqual(1, 2);
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}
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[TestCase(SourceKind.Sequence)]
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[TestCase(SourceKind.BreakingList)]
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[TestCase(SourceKind.BreakingReadOnlyList)]
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public void KeepsNonTrailingItemsThatMatchPredicate(SourceKind sourceKind)
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{
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using var sequence = TestingSequence.Of(1, 2, 0, 0, 3, 4, 0, 0);
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sequence.ToSourceKind(sourceKind)
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.SkipLastWhile(x => x == 0)
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.AssertSequenceEqual(1, 2, 0, 0, 3, 4);
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}
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}
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}

‎MoreLinq/Extensions.g.cs

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@@ -5460,6 +5460,32 @@ public static IEnumerable<T> SkipLast<T>(this IEnumerable<T> source, int count)
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}
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/// <summary><c>SkipLastWhile</c> extension.</summary>
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[GeneratedCode("MoreLinq.ExtensionsGenerator", "1.0.0.0")]
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public static partial class SkipLastWhileExtension
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{
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/// <summary>
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/// Removes elements from the end of a sequence as long as a specified condition is true.
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/// </summary>
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/// <typeparam name="T">Type of the source sequence.</typeparam>
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/// <param name="source">The source sequence.</param>
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/// <param name="predicate">The predicate to use to remove items from the tail of the sequence.</param>
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/// <returns>
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/// An <see cref="IEnumerable{T}"/> containing the source sequence elements except for the bypassed ones at the end.
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/// </returns>
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/// <exception cref="ArgumentNullException">The source sequence is <see langword="null"/>.</exception>
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/// <exception cref="ArgumentNullException">The predicate is <see langword="null"/>.</exception>
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/// <remarks>
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/// This operator uses deferred execution and streams its results. At any given time, it
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/// will buffer as many consecutive elements as satisfied by <paramref name="predicate"/>.
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/// </remarks>
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public static IEnumerable<T> SkipLastWhile<T>(this IEnumerable<T> source, Func<T, bool> predicate)
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=> MoreEnumerable.SkipLastWhile(source, predicate);
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}
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/// <summary><c>SkipUntil</c> extension.</summary>
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[GeneratedCode("MoreLinq.ExtensionsGenerator", "1.0.0.0")]

‎MoreLinq/MoreLinq.csproj

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@@ -86,6 +86,7 @@
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- Sequence
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- Shuffle
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- SkipLast
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- SkipLastWhile
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- SkipUntil
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- Slice
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- SortedMerge

‎MoreLinq/PublicAPI/net6.0/PublicAPI.Unshipped.txt

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#nullable enable
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MoreLinq.Extensions.SkipLastWhileExtension
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static MoreLinq.Extensions.SkipLastWhileExtension.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!

‎MoreLinq/PublicAPI/net8.0/PublicAPI.Unshipped.txt

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@@ -1,4 +1,7 @@
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#nullable enable
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MoreLinq.Extensions.SkipLastWhileExtension
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static MoreLinq.Extensions.SkipLastWhileExtension.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.Sequence<T>(T start) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.Sequence<T>(T start, T stop) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.Sequence<T>(T start, T stop, T step) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!

‎MoreLinq/PublicAPI/net9.0/PublicAPI.Unshipped.txt

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@@ -94,6 +94,7 @@ MoreLinq.Extensions.ShuffleExtension
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MoreLinq.Extensions.SingleExtension
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MoreLinq.Extensions.SingleOrDefaultExtension
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MoreLinq.Extensions.SkipLastExtension
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MoreLinq.Extensions.SkipLastWhileExtension
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MoreLinq.Extensions.SkipUntilExtension
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MoreLinq.Extensions.SliceExtension
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MoreLinq.Extensions.SortedMergeExtension
@@ -339,6 +340,7 @@ static MoreLinq.Extensions.ShuffleExtension.Shuffle<T>(this System.Collections.G
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static MoreLinq.Extensions.SingleExtension.Single<T>(this MoreLinq.IExtremaEnumerable<T>! source) -> T
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static MoreLinq.Extensions.SingleOrDefaultExtension.SingleOrDefault<T>(this MoreLinq.IExtremaEnumerable<T>! source) -> T?
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static MoreLinq.Extensions.SkipLastExtension.SkipLast<T>(this System.Collections.Generic.IEnumerable<T>! source, int count) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.Extensions.SkipLastWhileExtension.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.Extensions.SkipUntilExtension.SkipUntil<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, System.Func<TSource, bool>! predicate) -> System.Collections.Generic.IEnumerable<TSource>!
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static MoreLinq.Extensions.SliceExtension.Slice<T>(this System.Collections.Generic.IEnumerable<T>! sequence, int startIndex, int count) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.Extensions.SortedMergeExtension.SortedMerge<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, MoreLinq.OrderByDirection direction, params System.Collections.Generic.IEnumerable<TSource>![]! otherSequences) -> System.Collections.Generic.IEnumerable<TSource>!
@@ -619,6 +621,7 @@ static MoreLinq.MoreEnumerable.Shuffle<T>(this System.Collections.Generic.IEnume
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static MoreLinq.MoreEnumerable.Single<T>(this MoreLinq.IExtremaEnumerable<T>! source) -> T
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static MoreLinq.MoreEnumerable.SingleOrDefault<T>(this MoreLinq.IExtremaEnumerable<T>! source) -> T?
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static MoreLinq.MoreEnumerable.SkipLast<T>(System.Collections.Generic.IEnumerable<T>! source, int count) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.SkipUntil<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, System.Func<TSource, bool>! predicate) -> System.Collections.Generic.IEnumerable<TSource>!
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static MoreLinq.MoreEnumerable.Slice<T>(this System.Collections.Generic.IEnumerable<T>! sequence, int startIndex, int count) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.SortedMerge<TSource>(this System.Collections.Generic.IEnumerable<TSource>! source, MoreLinq.OrderByDirection direction, params System.Collections.Generic.IEnumerable<TSource>![]! otherSequences) -> System.Collections.Generic.IEnumerable<TSource>!

‎MoreLinq/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt

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#nullable enable
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MoreLinq.Extensions.SkipLastWhileExtension
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static MoreLinq.Extensions.SkipLastWhileExtension.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!

‎MoreLinq/PublicAPI/netstandard2.1/PublicAPI.Unshipped.txt

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#nullable enable
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MoreLinq.Extensions.SkipLastWhileExtension
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static MoreLinq.Extensions.SkipLastWhileExtension.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!
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static MoreLinq.MoreEnumerable.SkipLastWhile<T>(this System.Collections.Generic.IEnumerable<T>! source, System.Func<T, bool>! predicate) -> System.Collections.Generic.IEnumerable<T>!

‎MoreLinq/SkipLastWhile.cs

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#region License and Terms
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// MoreLINQ - Extensions to LINQ to Objects
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// Copyright (c) 2024 Andy Romero (armorynode). All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#endregion
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namespace MoreLinq
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{
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using System;
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using System.Collections.Generic;
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static partial class MoreEnumerable
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{
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/// <summary>
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/// Removes elements from the end of a sequence as long as a specified condition is true.
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/// </summary>
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/// <typeparam name="T">Type of the source sequence.</typeparam>
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/// <param name="source">The source sequence.</param>
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/// <param name="predicate">The predicate to use to remove items from the tail of the sequence.</param>
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/// <returns>
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/// An <see cref="IEnumerable{T}"/> containing the source sequence elements except for the bypassed ones at the end.
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/// </returns>
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/// <exception cref="ArgumentNullException">The source sequence is <see langword="null"/>.</exception>
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/// <exception cref="ArgumentNullException">The predicate is <see langword="null"/>.</exception>
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/// <remarks>
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/// This operator uses deferred execution and streams its results. At any given time, it
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/// will buffer as many consecutive elements as satisfied by <paramref name="predicate"/>.
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/// </remarks>
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public static IEnumerable<T> SkipLastWhile<T>(this IEnumerable<T> source, Func<T, bool> predicate)
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{
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if (source == null) throw new ArgumentNullException(nameof(source));
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if (predicate == null) throw new ArgumentNullException(nameof(predicate));
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return source.TryAsListLike() switch
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{
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{ } list => IterateList(list, predicate),
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_ => IterateSequence(source, predicate),
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};
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static IEnumerable<T> IterateList(ListLike<T> list, Func<T, bool> predicate)
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{
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var i = list.Count - 1;
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while (i >= 0 && predicate(list[i]))
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{
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i--;
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}
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for (var j = 0; j <= i; j++)
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{
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yield return list[j];
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}
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}
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static IEnumerable<T> IterateSequence(IEnumerable<T> source, Func<T, bool> predicate)
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{
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Queue<T>? queue = null;
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foreach (var item in source)
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{
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if (predicate(item))
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{
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queue ??= new Queue<T>();
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queue.Enqueue(item);
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}
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else
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{
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while (queue?.Count > 0)
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{
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yield return queue.Dequeue();
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}
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yield return item;
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}
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}
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}
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}
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}
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}

‎README.md

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Bypasses a specified number of elements at the end of the sequence.
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### SkipLastWhile
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Removes elements from the end of a sequence as long as a specified condition is true.
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### SkipUntil
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Skips items from the input sequence until the given predicate returns true

‎bld/Copyright.props

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Portions &#169; 2016 Andreas Gullberg Larsen, Leandro F. Vieira (leandromoh).
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Portions &#169; 2017 Jonas Nyrup (jnyrup).
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Portions &#169; 2023 Julien Aspirot (julienasp).
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Portions &#169; 2024 Andy Romero (armorynode).
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Portions &#169; Microsoft. All rights reserved.
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</Copyright>
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</PropertyGroup>

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