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Commit df7a63e

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Merge pull request #3 from rvhuang/wip-enumerable-source
Support deferred execution
2 parents 3e1e8c4 + da1124a commit df7a63e

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9 files changed

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‎README.md‎

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**KMP Algorithm .NET** is the .NET implementation of Knuth–Morris–Pratt algorithm. The project defines a set of extension methods that apply the algorithm to strings and lists.
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Unlike traditional KMP algorithm uses which are focused on string searching, the project provides a generic programming model of using KMP algorithm on [IList(T)](https://docs.microsoft.com/en-us/dotnet/core/api/system.collections.generic.ilist-1) and [IReadOnlyList(T)](https://docs.microsoft.com/en-us/dotnet/core/api/system.collections.generic.ireadonlylist-1), as long as type T is [equatable](https://docs.microsoft.com/en-us/dotnet/core/api/system.iequatable-1). This expands the applicability of the algorithm, making searching an array of bytes in a longer array, or a collection of floats in an array of floats with same algorithm possible. In some cases, you may specify optional parameter [IEqualityComparer(T)](https://docs.microsoft.com/en-us/dotnet/core/api/system.collections.generic.iequalitycomparer-1) instance to provide different comparison behavior for type T.
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Unlike traditional KMP algorithm uses which are focused on string instances, the project provides a set of generic APIs that apply KMP algorithm to [IEnumerable(T)](https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.ienumerable-1), [IList(T)](https://docs.microsoft.com/en-us/dotnet/core/api/system.collections.generic.ilist-1) and [IReadOnlyList(T)](https://docs.microsoft.com/en-us/dotnet/core/api/system.collections.generic.ireadonlylist-1), as long as type T is [equatable](https://docs.microsoft.com/en-us/dotnet/core/api/system.iequatable-1). This expands the applicability of the algorithm, making searching an array of bytes in a longer array, or a collection of floats in an array of floats with same algorithm possible. In some cases, you may specify optional parameter [IEqualityComparer(T)](https://docs.microsoft.com/en-us/dotnet/core/api/system.collections.generic.iequalitycomparer-1) instance to provide different comparison behavior for type `T`.
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The project also includes a "backward" version of KMP algorithm that searches the last occurrence of the target within the instance.
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@@ -67,13 +67,44 @@ The project provides iterator pattern for forward and backward index enumeration
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In this example, caller can start enumerating each index before all indexes are found.
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### Searching in Deferred Execution
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The project provides a set of `IndexOf` APIs optimized for [IEnumerable(T)](https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.ienumerable-1) instance that is produced in **deferred execution**. That is, the search can start before whole collection is ready. The APIs are defined in `AlgorithmForce.Searching.Deferred` namespace.
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The following example shows how to search an array of numbers in `Enumerable.Range()`.
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```cs
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// using AlgorithmForce.Searching.Deferred
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var s = Enumerable.Range(0, 100); // deferred execution
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var t = new[] { 95, 96, 97, 98, 99 };
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Console.WriteLine(s.IndexOf(t)); // 95
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```
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A set of APIs that wrap [TextReader](https://docs.microsoft.com/en-us/dotnet/api/system.io.textreader) and [BinaryReader](https://docs.microsoft.com/en-us/dotnet/api/system.io.binaryreader) as `IEnumerable(T)` instances can be used together in order to search the collection in streamed content. The following code snippet shows how to search an array in `StringReader` by applying `AsCharEnumerable()` API.
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```cs
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var s = "Vrogros, the Underlord, is a melee strength hero.";
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var t = new[] { 'U', 'n', 'd', 'e', 'r', 'l', 'o', 'r', 'd' };
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using (var reader = new StringReader(s))
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{
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Console.WriteLine(reader.AsCharEnumerable().IndexOf(t));
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// 13
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}
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```
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## Future Works
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* Source collection with deferred execution
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* `IndexOfAny()` and `IndexesOfAll()` implementation
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* Vertical Search in a collecton of collections
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* `IndexOfAny` implementation
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## Platform
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This project currently targets .NET Core only.
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This project targets [.NET Standard 1.6](https://github.com/dotnet/standard/blob/master/docs/versions/netstandard1.6.md) currently.
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## License
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The project is licesed under the [MIT license](LICENSE). Feel free to use and modify the code in your algorithm homeworks.
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‎src/AlgorithmForce.Searching.Test/AlgorithmForce.Searching.Test.csproj‎

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</PropertyGroup>
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<ItemGroup>
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<Compile Include="..\AlgorithmForce.Searching\Extensions.cs;..\AlgorithmForce.Searching\ListWrapper.cs;..\AlgorithmForce.Searching\StringWrapper.cs" />
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<Compile Include="..\AlgorithmForce.Searching\Extensions.cs;" />
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<Compile Include="..\AlgorithmForce.Searching\ListWrapper.cs;" />
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<Compile Include="..\AlgorithmForce.Searching\StringWrapper.cs;" />
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<Compile Include="..\AlgorithmForce.Searching\TableBuilder.cs;" />
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<Compile Include="..\AlgorithmForce.Searching\Deferred\EnumerableExtensions.cs;" />
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<Compile Include="..\AlgorithmForce.Searching\Deferred\ReaderExtensions.cs;" />
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</ItemGroup>
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<ItemGroup>
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using System.IO;
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using System.Linq;
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using Xunit;
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using Xunit.Abstractions;
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namespace AlgorithmForce.Searching.Test
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{
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using Deferred;
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public class EnumerableExtensionsTest
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{
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private readonly ITestOutputHelper _output;
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public EnumerableExtensionsTest(ITestOutputHelper output)
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{
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_output = output;
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}
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[Fact]
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public void TestCaseEnumerableIndexOf()
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{
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var s = Enumerable.Range(0, 100);
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var t = new[] { 95, 96, 97, 98, 99 };
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Assert.Equal(95, EnumerableExtensions.IndexOf(s, t, 0, null));
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}
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[Fact]
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public void TestCaseEnumerableIndexOfNotFound()
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{
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var s = Enumerable.Range(0, 100);
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var t = new[] { 90, 92, 94, 96, 98 };
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Assert.Equal(-1, EnumerableExtensions.IndexOf(s, t, 0, null));
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}
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[Fact]
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public void TestCaseEnumerableIndexOfWithTextReader()
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{
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var s = string.Concat("Vrogros, the Underlord, is a melee strength hero ",
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"whose commanding presence is crucial to his team's success. ",
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"With his long-lasting abilities, Underlord is able to ",
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"control wide areas of the battlefield during teamfights.");
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var t = new[] { 'U', 'n', 'd', 'e', 'r', 'l', 'o', 'r', 'd' };
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using (var reader = new StringReader(s))
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{
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Assert.Equal(s.IndexOf(string.Concat(t)), EnumerableExtensions.IndexOf(reader.AsCharEnumerable(), t, 0, null));
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}
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}
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[Fact]
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public void TestCaseEnumerableIndexOfWithTextReaderNotFound()
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{
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var s = string.Concat("Vrogros, the Underlord, is a melee strength hero ",
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"whose commanding presence is crucial to his team's success. ",
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"With his long-lasting abilities, Underlord is able to ",
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"control wide areas of the battlefield during teamfights.");
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var t = new[] { 'S', 'u', 'n', ' ', 'W', 'u', 'k', 'o', 'n', 'g' };
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using (var reader = new StringReader(s))
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{
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Assert.Equal(s.IndexOf(string.Concat(t)), EnumerableExtensions.IndexOf(reader.AsCharEnumerable(), t, 0, null));
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}
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}
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[Fact]
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public void TestCaseEnumerableIndexOfWithStartIndex()
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{
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var s = Enumerable.Range(0, 100);
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var t = new[] { 95, 96, 97, 98, 99 };
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Assert.Equal(95, EnumerableExtensions.IndexOf(s, t, 20, null));
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}
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[Fact]
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public void TestCaseEnumerableIndexOfWithStartIndexNotFound()
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{
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var s = Enumerable.Range(0, 100);
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var t = new[] { 95, 96, 97, 98, 99 };
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Assert.Equal(-1, EnumerableExtensions.IndexOf(s, t, 97, null));
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}
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[Fact]
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public void TestCaseEnumerableIndexOfWithTextReaderAndStartIndex()
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{
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var s = string.Concat("Vrogros, the Underlord, is a melee strength hero ",
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"whose commanding presence is crucial to his team's success. ",
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"With his long-lasting abilities, Underlord is able to ",
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"control wide areas of the battlefield during teamfights.");
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var t = new[] { 'U', 'n', 'd', 'e', 'r', 'l', 'o', 'r', 'd' };
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using (var reader = new StringReader(s))
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{
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Assert.Equal(s.IndexOf(string.Concat(t), 160), EnumerableExtensions.IndexOf(reader.AsCharEnumerable(), t, 160, null));
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}
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}
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[Fact]
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public void SkipTest()
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{
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var s = Enumerable.Range(5, 100);
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using (var enumerator = s.GetEnumerator())
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{
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EnumerableExtensions.Skip(enumerator, 55).MoveNext();
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Assert.Equal(s.Skip(55).First(), enumerator.Current);
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}
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}
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}
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}

‎src/AlgorithmForce.Searching.Test/TableBuildingTest.cs‎

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{
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var input = "abcabx";
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var expected = new[] { -1, 0, 0, 0, 1, 2 };
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var actual = Extensions.BuildTable(input.AsReadOnlyList(), EqualityComparer<char>.Default);
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var actual = TableBuilder.BuildTable(input.AsReadOnlyList(), EqualityComparer<char>.Default);
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_output.WriteLine("Expected:\t{0}", string.Join(", ", expected));
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_output.WriteLine("Actual:\t{0}", string.Join(", ", actual));
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{
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var input = "abcdex";
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var expected = new[] { -1, 0, 0, 0, 0, 0 };
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var actual = Extensions.BuildTable(input.AsReadOnlyList(), EqualityComparer<char>.Default);
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var actual = TableBuilder.BuildTable(input.AsReadOnlyList(), EqualityComparer<char>.Default);
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_output.WriteLine("Expected:\t{0}", string.Join(", ", expected));
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_output.WriteLine("Actual:\t{0}", string.Join(", ", actual));
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{
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var input = "ababaaaba";
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var expected = new[] { -1, 0, 0, 1, 2, 3, 1, 1, 2 };
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var actual = Extensions.BuildTable(input.AsReadOnlyList(), EqualityComparer<char>.Default);
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var actual = TableBuilder.BuildTable(input.AsReadOnlyList(), EqualityComparer<char>.Default);
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_output.WriteLine("Expected:\t{0}", string.Join(", ", expected));
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_output.WriteLine("Actual:\t{0}", string.Join(", ", actual));
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{
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var input = "aaaaaaaab";
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var expected = new[] { -1, 0, 1, 2, 3, 4, 5, 6, 7 };
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var actual = Extensions.BuildTable(input.AsReadOnlyList(), EqualityComparer<char>.Default);
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var actual = TableBuilder.BuildTable(input.AsReadOnlyList(), EqualityComparer<char>.Default);
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_output.WriteLine("Expected:\t{0}", string.Join(", ", expected));
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_output.WriteLine("Actual:\t{0}", string.Join(", ", actual));

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