Added contains and aligned string.Empty in IndexOf

Author: linkdotnet

CHANGELOG.md

@@ -6,8 +6,12 @@ All notable changes to **ValueStringBuilder** will be documented in this file. T
 
 ## [Unreleased]
 
+###Added
+ - `Contains` method.
+
 ### Fixed
  - Smaller tweaks in CI/CD
+ - `IndexOf` and `LastIndexOf` did not return 0 when passing an empty string. Now it is aligned to `string.IndexOf`.
 
 ### Removed
  - Debug symbol package (snupkg) due to the many constraints of NuGet.org
@@ -76,4 +80,4 @@ This release brings extensions to the `ValueStringBuilder` API. For `v1.0` the `
 
 [1.0.0]: https://github.com/linkdotnet/StringBuilder/compare/0.9.5...1.0.0
 
-[0.9.5]: https://github.com/linkdotnet/StringBuilder/compare/0.9.4...0.9.5
+[0.9.5]: https://github.com/linkdotnet/StringBuilder/compare/0.9.4...0.9.5

src/LinkDotNet.StringBuilder/LinkDotNet.StringBuilder.csproj

@@ -16,6 +16,7 @@
         <PackageReadmeFile>README.md</PackageReadmeFile>
         <PackageIcon>logo.png</PackageIcon>
         <PackageIconUrl>https://github.com/linkdotnet/StringBuilder/blob/main/logo.png</PackageIconUrl>
+        <PublishRepositoryUrl>true</PublishRepositoryUrl>
     </PropertyGroup>
 
     <ItemGroup>

src/LinkDotNet.StringBuilder/ValueStringBuilder.cs

@@ -172,6 +172,11 @@ public int IndexOf(ReadOnlySpan<char> word, int startIndex)
             throw new ArgumentOutOfRangeException(nameof(startIndex), "Start index can't be smaller than 0.");
         }
 
+        if (word.IsEmpty)
+        {
+            return 0;
+        }
+
         return NaiveSearch.FindFirst(buffer[startIndex..bufferPosition], word);
     }
 
@@ -196,9 +201,24 @@ public int LastIndexOf(ReadOnlySpan<char> word, int startIndex)
             throw new ArgumentOutOfRangeException(nameof(startIndex), "Start index can't be smaller than 0.");
         }
 
+        if (word.IsEmpty)
+        {
+            return 0;
+        }
+
         return NaiveSearch.FindLast(buffer[startIndex..bufferPosition], word);
     }
 
+    /// <summary>
+    /// Returns a value indicating whether a specified substring occurs within this string.
+    /// </summary>
+    /// <param name="word">Word to look for in this string.</param>
+    /// <returns>True if the value parameter occurs within this string, or if value is the empty string (""); otherwise, false.</returns>
+    /// <remarks>
+    /// This method performs an ordinal (case-sensitive and culture-insensitive) comparison.
+    /// </remarks>
+    public bool Contains(ReadOnlySpan<char> word) => IndexOf(word) != -1;
+
     private void Grow(int capacity = 0)
     {
         var currentSize = buffer.Length;

tests/LinkDotNet.StringBuilder.UnitTests/ValueStringBuilderTests.cs

@@ -217,15 +217,13 @@ public void ShouldReturnMinusOneWordIsLongerThanString()
         index.Should().Be(-1);
     }
 
-    [Theory]
-    [InlineData("", "word")]
-    [InlineData("word", "")]
-    public void ShouldReturnMinusOneIfStringOrWordIsEmpty(string text, string word)
+    [Fact]
+    public void ShouldReturnMinusOneIfStringIsEmpty()
     {
         var stringBuilder = new ValueStringBuilder();
-        stringBuilder.Append(text);
+        stringBuilder.Append(string.Empty);
 
-        var index = stringBuilder.IndexOf(word);
+        var index = stringBuilder.IndexOf("word");
 
         index.Should().Be(-1);
     }
@@ -289,4 +287,40 @@ public void ShouldFindLastOccurenceInSlice()
 
         index.Should().Be(0);
     }
+
+    [Fact]
+    public void ShouldReturnZeroWhenEmptyStringInIndexOf()
+    {
+        var builder = new ValueStringBuilder();
+        builder.Append("Hello");
+
+        var index = builder.IndexOf(string.Empty, 6);
+
+        index.Should().Be(0);
+    }
+
+    [Fact]
+    public void ShouldReturnZeroWhenEmptyStringInLastIndexOf()
+    {
+        var builder = new ValueStringBuilder();
+        builder.Append("Hello");
+
+        var index = builder.LastIndexOf(string.Empty, 6);
+
+        index.Should().Be(0);
+    }
+
+    [Theory]
+    [InlineData("Hello", true)]
+    [InlineData("hello", false)]
+    [InlineData("", true)]
+    public void ShouldReturnIfStringIsPresent(string word, bool expected)
+    {
+        var builder = new ValueStringBuilder();
+        builder.Append("Hello");
+
+        var index = builder.Contains(word);
+
+        index.Should().Be(expected);
+    }
 }