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CountDown should throw on negative count #133

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Dec 28, 2022
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CountDown should throw on negative count #133

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5c6d36b
`CountDown` should throw on negative `count`
viceroypenguin Dec 28, 2022
952ec04
Update `CountDown` documentation
viceroypenguin Dec 28, 2022
c2339f5
Fix tests
viceroypenguin Dec 28, 2022
4c21615
Add corner case test
viceroypenguin Dec 28, 2022
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74 changes: 43 additions & 31 deletions Source/SuperLinq.Async/CountDown.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,67 +3,79 @@
public static partial class AsyncSuperEnumerable
{
/// <summary>
/// Provides a countdown counter for a given count of elements at the
/// tail of the sequence where zero always represents the last element,
/// one represents the second-last element, two represents the
/// third-last element and so on.
/// Provides a countdown counter for a given count of elements at the tail of the sequence where zero always
/// represents the last element, one represents the second-last element, two represents the third-last element and
/// so on.
/// </summary>
/// <typeparam name="TSource">
/// The type of elements of <paramref name="source"/></typeparam>
/// <param name="source">The source sequence.</param>
/// <param name="count">Count of tail elements of
/// <paramref name="source"/> to count down.</param>
/// <param name="count">Count of tail elements of <paramref name="source"/> to count down.</param>
/// <returns>
/// A sequence of tuples of the element and it's count from the end of the sequence.
/// </returns>
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="source"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="count"/> is <c>0</c> or negative.
/// </exception>
/// <remarks>
/// This method uses deferred execution semantics and streams its
/// results. At most, <paramref name="count"/> elements of the source
/// sequence may be buffered at any one time unless
/// <paramref name="source"/> is a collection or a list.
/// <para>
/// This method uses deferred execution semantics and streams its results. At most, <paramref name="count"/>
/// elements of the source sequence may be buffered at any one time unless <paramref name="source"/> is a collection
/// or a list.
/// </para>
/// <para>
/// This operator executes immediately.
/// </para>
/// </remarks>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
public static IAsyncEnumerable<(TSource item, int? count)> CountDown<TSource>(this IAsyncEnumerable<TSource> source, int count)
{
return source.CountDown(count, ValueTuple.Create);
}

/// <summary>
/// Provides a countdown counter for a given count of elements at the
/// tail of the sequence where zero always represents the last element,
/// one represents the second-last element, two represents the
/// third-last element and so on.
/// Provides a countdown counter for a given count of elements at the tail of the sequence where zero always
/// represents the last element, one represents the second-last element, two represents the third-last element and
/// so on.
/// </summary>
/// <typeparam name="TSource">
/// The type of elements of <paramref name="source"/></typeparam>
/// <typeparam name="TResult">
/// The type of elements of the resulting sequence.</typeparam>
/// <param name="source">The source sequence.</param>
/// <param name="count">Count of tail elements of
/// <paramref name="source"/> to count down.</param>
/// <param name="count">Count of tail elements of <paramref name="source"/> to count down.</param>
/// <param name="resultSelector">
/// A function that receives the element and the current countdown
/// value for the element and which returns those mapped to a
/// result returned in the resulting sequence. For elements before
/// the last <paramref name="count"/>, the countdown value is
/// <see langword="null"/>.</param>
/// A function that receives the element and the current countdown value for the element and which returns those
/// mapped to a result returned in the resulting sequence. For elements before the last <paramref name="count"/>,
/// the countdown value is <see langword="null"/>.</param>
/// <returns>
/// A sequence of results returned by
/// <paramref name="resultSelector"/>.</returns>
/// A sequence of results returned by <paramref name="resultSelector"/>.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="source"/> or <paramref name="resultSelector"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="count"/> is <c>0</c> or negative.
/// </exception>
/// <remarks>
/// This method uses deferred execution semantics and streams its
/// results. At most, <paramref name="count"/> elements of the source
/// sequence may be buffered at any one time unless
/// <paramref name="source"/> is a collection or a list.
/// <para>
/// This method uses deferred execution semantics and streams its results. At most, <paramref name="count"/>
/// elements of the source sequence may be buffered at any one time unless <paramref name="source"/> is a collection
/// or a list.
/// </para>
/// <para>
/// This operator executes immediately.
/// </para>
/// </remarks>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="ArgumentNullException"><paramref name="resultSelector"/> is <see langword="null"/>.</exception>
public static IAsyncEnumerable<TResult> CountDown<TSource, TResult>(
this IAsyncEnumerable<TSource> source,
int count, Func<TSource, int?, TResult> resultSelector)
{
Guard.IsNotNull(source);
Guard.IsNotNull(resultSelector);
Guard.IsGreaterThanOrEqualTo(count, 1);

return _(source, count, resultSelector);

Expand Down
73 changes: 42 additions & 31 deletions Source/SuperLinq/CountDown.cs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,68 +3,79 @@
public static partial class SuperEnumerable
{
/// <summary>
/// Provides a countdown counter for a given count of elements at the
/// tail of the sequence where zero always represents the last element,
/// one represents the second-last element, two represents the
/// third-last element and so on.
/// Provides a countdown counter for a given count of elements at the tail of the sequence where zero always
/// represents the last element, one represents the second-last element, two represents the third-last element and
/// so on.
/// </summary>
/// <typeparam name="TSource">
/// The type of elements of <paramref name="source"/></typeparam>
/// <param name="source">The source sequence.</param>
/// <param name="count">Count of tail elements of
/// <paramref name="source"/> to count down.</param>
/// <param name="count">Count of tail elements of <paramref name="source"/> to count down.</param>
/// <returns>
/// A sequence of tuples of the element and it's count from the end of the sequence.
/// </returns>
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="source"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="count"/> is <c>0</c> or negative.
/// </exception>
/// <remarks>
/// This method uses deferred execution semantics and streams its
/// results. At most, <paramref name="count"/> elements of the source
/// sequence may be buffered at any one time unless
/// <paramref name="source"/> is a collection or a list.
/// <para>
/// This method uses deferred execution semantics and streams its results. At most, <paramref name="count"/>
/// elements of the source sequence may be buffered at any one time unless <paramref name="source"/> is a collection
/// or a list.
/// </para>
/// <para>
/// This operator executes immediately.
/// </para>
/// </remarks>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
public static IEnumerable<(TSource item, int? count)> CountDown<TSource>(this IEnumerable<TSource> source, int count)
{
return source.CountDown(count, ValueTuple.Create);
}

/// <summary>
/// Provides a countdown counter for a given count of elements at the
/// tail of the sequence where zero always represents the last element,
/// one represents the second-last element, two represents the
/// third-last element and so on.
/// Provides a countdown counter for a given count of elements at the tail of the sequence where zero always
/// represents the last element, one represents the second-last element, two represents the third-last element and
/// so on.
/// </summary>
/// <typeparam name="TSource">
/// The type of elements of <paramref name="source"/></typeparam>
/// <typeparam name="TResult">
/// The type of elements of the resulting sequence.</typeparam>
/// <param name="source">The source sequence.</param>
/// <param name="count">Count of tail elements of
/// <paramref name="source"/> to count down.</param>
/// <param name="count">Count of tail elements of <paramref name="source"/> to count down.</param>
/// <param name="resultSelector">
/// A function that receives the element and the current countdown
/// value for the element and which returns those mapped to a
/// result returned in the resulting sequence. For elements before
/// the last <paramref name="count"/>, the countdown value is
/// <see langword="null"/>.</param>
/// A function that receives the element and the current countdown value for the element and which returns those
/// mapped to a result returned in the resulting sequence. For elements before the last <paramref name="count"/>,
/// the countdown value is <see langword="null"/>.</param>
/// <returns>
/// A sequence of results returned by
/// <paramref name="resultSelector"/>.
/// A sequence of results returned by <paramref name="resultSelector"/>.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="source"/> or <paramref name="resultSelector"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="count"/> is <c>0</c> or negative.
/// </exception>
/// <remarks>
/// This method uses deferred execution semantics and streams its
/// results. At most, <paramref name="count"/> elements of the source
/// sequence may be buffered at any one time unless
/// <paramref name="source"/> is a collection or a list.
/// <para>
/// This method uses deferred execution semantics and streams its results. At most, <paramref name="count"/>
/// elements of the source sequence may be buffered at any one time unless <paramref name="source"/> is a collection
/// or a list.
/// </para>
/// <para>
/// This operator executes immediately.
/// </para>
/// </remarks>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is <see langword="null"/>.</exception>
/// <exception cref="ArgumentNullException"><paramref name="resultSelector"/> is <see langword="null"/>.</exception>
public static IEnumerable<TResult> CountDown<TSource, TResult>(
this IEnumerable<TSource> source,
int count, Func<TSource, int?, TResult> resultSelector)
{
Guard.IsNotNull(source);
Guard.IsNotNull(resultSelector);
Guard.IsGreaterThanOrEqualTo(count, 1);

return source.TryGetCollectionCount(out var _)
? IterateCollection(source, count, resultSelector)
Expand Down
17 changes: 8 additions & 9 deletions Tests/SuperLinq.Async.Test/CountDownTest.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,6 @@
namespace Test.Async;
using SuperLinq;

namespace Test.Async;

public class CountDownTest
{
Expand All @@ -9,20 +11,17 @@ public void IsLazy()
.CountDown(42, BreakingFunc.Of<object, int?, object>());
}

[Fact]
public Task WithNegativeCount()
[Theory]
[InlineData(0), InlineData(-1)]
public void ExceptionOnNegativeCount(int param)
{
const int count = 10;
return AsyncEnumerable.Range(1, count)
.CountDown(-1000, (_, cd) => cd)
.AssertSequenceEqual(Enumerable.Repeat((int?)null, count));
Assert.Throws<ArgumentOutOfRangeException>("count", () =>
AsyncSeq(1).CountDown(param));
}

private static IEnumerable<T> GetData<T>(Func<int[], int, int?[], T> selector)
{
var xs = Enumerable.Range(0, 5).ToArray();
yield return selector(xs, -1, new int?[] { null, null, null, null, null });
yield return selector(xs, 0, new int?[] { null, null, null, null, null });
yield return selector(xs, 1, new int?[] { null, null, null, null, 0 });
yield return selector(xs, 2, new int?[] { null, null, null, 1, 0 });
yield return selector(xs, 3, new int?[] { null, null, 2, 1, 0 });
Expand Down
12 changes: 5 additions & 7 deletions Tests/SuperLinq.Test/CountDownTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,19 +12,17 @@ public void IsLazy()
.CountDown(42, BreakingFunc.Of<object, int?, object>());
}

[Fact]
public void WithNegativeCount()
[Theory]
[InlineData(0), InlineData(-1)]
public void ExceptionOnNegativeCount(int param)
{
Enumerable.Range(1, 10)
.CountDown(-1000, (_, cd) => cd)
.AssertSequenceEqual(Enumerable.Repeat((int?)null, 10));
Assert.Throws<ArgumentOutOfRangeException>("count", () =>
Seq(1).CountDown(param));
}

public static IEnumerable<T> GetData<T>(Func<int[], int, int?[], T> selector)
{
var xs = Enumerable.Range(0, 5).ToArray();
yield return selector(xs, -1, new int?[] { null, null, null, null, null });
yield return selector(xs, 0, new int?[] { null, null, null, null, null });
yield return selector(xs, 1, new int?[] { null, null, null, null, 0 });
yield return selector(xs, 2, new int?[] { null, null, null, 1, 0 });
yield return selector(xs, 3, new int?[] { null, null, 2, 1, 0 });
Expand Down