Optimize ArrayView and StringView

Directory.Packages.props

@@ -9,6 +9,5 @@
     <PackageVersion Include="MinVer" Version="6.0.0" />
     <PackageVersion Include="NUnit" Version="4.3.2" />
     <PackageVersion Include="NUnit3TestAdapter" Version="5.0.0" />
-    <PackageVersion Include="System.Collections.Immutable" Version="6.0.0" />
   </ItemGroup>
 </Project>

README.md

@@ -47,16 +47,6 @@ foreach (ref readonly HeavyStruct s in view)
 }
 
 ```
-## Changelog
-
-### 1.2.2
-- Optimize `ArrayView.Create` method for empty collection expression
-
-### 1.2.1
-- Add `List<T>` to `ArrayView<T>` extension for NET9.0+
-
-### 1.2.0
-- Add `Trim` overloads to `StringView` class
 
 ## Supported versions
 

Ramstack.Structures.Tests/Collections/ArrayViewExtensionsTests.cs

@@ -1,10 +1,10 @@
 namespace Ramstack.Collections;
 
+#if NET9_0_OR_GREATER
+
 [TestFixture]
 public class ArrayViewExtensionsTests
 {
-    #if NET9_0_OR_GREATER
-
     [Test]
     public void List_AsView_Empty()
     {
@@ -25,5 +25,6 @@ public void List_AsView()
         Assert.That(view, Is.EquivalentTo(list));
     }
 
-    #endif
 }
+
+#endif

Ramstack.Structures/Collections/ArrayViewExtensions.cs

@@ -149,9 +149,13 @@ public static ArrayView<T> AsView<T>(this List<T>? list)
         if (list is not null)
         {
             var array = ListAccessor<T>.GetArray(list);
-            var count = Math.Min(list.Count, array.Length);
+            _ = array.Length;
 
-            return new ArrayView<T>(array, 0, count);
+            //
+            // SCG.List<T> maintains internal invariants, so we can safely use the unchecked constructor
+            // to bypass redundant bounds checks for better performance.
+            //
+            return new ArrayView<T>(array, 0, list.Count, unused: 0);
         }
 
         return ArrayView<T>.Empty;

Ramstack.Structures/Collections/ArrayView`1.cs

@@ -101,17 +101,23 @@ public ArrayView(T[] array, int index, int length)
     /// Initializes a new instance of the <see cref="ArrayView{T}"/> structure that creates
     /// a view for the specified range of the elements in the specified array.
     /// </summary>
+    /// <remarks>
+    /// This constructor is intentionally minimal and skips all argument validations,
+    /// as the caller is responsible for ensuring correctness (e.g.,
+    /// <paramref name="array"/> is non-null, <paramref name="index"/> and
+    /// <paramref name="length"/> are within bounds).
+    /// </remarks>
     /// <param name="array">The array to wrap.</param>
     /// <param name="index">The zero-based index of the first element in the range.</param>
     /// <param name="length">The number of elements in the range.</param>
-    /// <param name="dummy">The dummy parameter.</param>
+    /// <param name="unused">Unused parameter, exists solely to disambiguate overloads.</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private ArrayView(T[] array, int index, int length, int dummy)
+    internal ArrayView(T[] array, int index, int length, int unused)
     {
         _index = index;
         _count = length;
         _array = array;
-        _ = dummy;
+        _ = unused;
     }
 
     /// <inheritdoc cref="IEnumerable{T}.GetEnumerator"/>
@@ -132,7 +138,7 @@ public ArrayView<T> Slice(int index)
         if ((uint)index > (uint)_count)
             ThrowHelper.ThrowArgumentOutOfRangeException();
 
-        return new ArrayView<T>(_array!, _index + index, _count - index, dummy: 0);
+        return new ArrayView<T>(_array!, _index + index, _count - index, unused: 0);
     }
 
     /// <summary>
@@ -157,7 +163,7 @@ public ArrayView<T> Slice(int index, int count)
                 ThrowHelper.ThrowArgumentOutOfRangeException();
         }
 
-        return new ArrayView<T>(_array!, _index + index, count, dummy: 0);
+        return new ArrayView<T>(_array!, _index + index, count, unused: 0);
     }
 
     /// <summary>
@@ -316,7 +322,7 @@ ref array.GetRawArrayData(view._index),
     /// A <see cref="ArrayView{T}"/> representation of the array segment.
     /// </returns>
     public static implicit operator ArrayView<T>(ArraySegment<T> segment) =>
-        new(segment.Array!, segment.Offset, segment.Count, dummy: 0);
+        new(segment.Array!, segment.Offset, segment.Count, unused: 0);
 
     /// <summary>
     /// Returns a string representation of the current instance's state,

Ramstack.Structures/Internal/JitHelpers.cs

@@ -30,7 +30,7 @@ public static ref readonly char GetRawStringData(this string text, int index) =>
     public static ref T GetRawArrayData<T>(this T[] array, int index)
     {
         // It's valid for a ref to point just past the end of an array, and it'll
-        // be properly GC-tracked. (Though dereferencing it may result in undefined behavior.)
+        // be properly GC-tracked. (Though dereferencing it may result in undefined behavior)
         return ref Unsafe.Add(ref MemoryMarshal.GetArrayDataReference(array), (nint)(uint)index);
     }
 }

Ramstack.Structures/Ramstack.Structures.csproj

@@ -64,11 +64,6 @@ Ramstack.Collections.ReadOnlyArray&lt;T&gt;</Description>
     </PackageReference>
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFramework)' == 'net6.0'">
-    <PackageReference Include="System.Collections.Immutable" />
-  </ItemGroup>
-
-
   <ItemGroup>
     <None Include="..\README.md" Link="Properties\README.md">
       <Pack>True</Pack>

Ramstack.Structures/Text/StringView.cs

@@ -45,7 +45,7 @@ public char this[int index]
     /// </summary>
     /// <param name="value">The string to wrap.</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public StringView(string value) : this(value, 0, value.Length, dummy: 0)
+    public StringView(string value) : this(value, 0, value.Length, unused: 0)
     {
     }
 
@@ -96,17 +96,23 @@ public StringView(string value, int index, int length)
     /// Initializes a new instance of the <see cref="StringView"/> structure that creates
     /// a view for the specified range of the characters in the specified string.
     /// </summary>
+    /// <remarks>
+    /// This constructor is intentionally minimal and skips all argument validations,
+    /// as the caller is responsible for ensuring correctness (e.g.,
+    /// <paramref name="value"/> is non-null, <paramref name="index"/> and
+    /// <paramref name="length"/> are within bounds).
+    /// </remarks>
     /// <param name="value">The string to wrap.</param>
     /// <param name="index">The zero-based index of the first character in the range.</param>
     /// <param name="length">The number of characters in the range.</param>
-    /// <param name="dummy">The dummy parameter.</param>
+    /// <param name="unused">Unused parameter, exists solely to disambiguate overloads.</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private StringView(string value, int index, int length, int dummy)
+    private StringView(string value, int index, int length, int unused)
     {
         _index = index;
         _length = length;
         _value = value;
-        _ = dummy;
+        _ = unused;
     }
 
     /// <inheritdoc cref="IEnumerable{T}.GetEnumerator"/>
@@ -156,7 +162,7 @@ public StringView Slice(int start)
         if ((uint)start > (uint)_length)
             ThrowHelper.ThrowArgumentOutOfRangeException();
 
-        return new StringView(_value!, _index + start, _length - start, dummy: 0);
+        return new StringView(_value!, _index + start, _length - start, unused: 0);
     }
 
     /// <summary>
@@ -182,7 +188,7 @@ public StringView Slice(int start, int length)
                 ThrowHelper.ThrowArgumentOutOfRangeException();
         }
 
-        return new StringView(_value!, _index + start, length, dummy: 0);
+        return new StringView(_value!, _index + start, length, unused: 0);
     }
 
     /// <summary>
@@ -256,7 +262,7 @@ public StringView TrimStart()
                 if (!char.IsWhiteSpace(value.GetRawStringData(start)))
                     break;
 
-        return new StringView(value!, start, final - start, dummy: 0);
+        return new StringView(value!, start, final - start, unused: 0);
     }
 
     /// <summary>
@@ -277,7 +283,7 @@ public StringView TrimStart(char trimChar)
                 if (value.GetRawStringData(start) != trimChar)
                     break;
 
-        return new StringView(value!, start, final - start, dummy: 0);
+        return new StringView(value!, start, final - start, unused: 0);
     }
 
     /// <summary>
@@ -306,7 +312,7 @@ public StringView TrimStart(params char[]? trimChars) =>
     /// <returns>
     /// The trimmed <see cref="StringView"/>.
     /// </returns>
-    public StringView TrimStart(ReadOnlySpan<char> trimChars)
+    public StringView TrimStart(params ReadOnlySpan<char> trimChars)
     {
         if (trimChars.Length == 0)
             return TrimStart();
@@ -319,16 +325,18 @@ public StringView TrimStart(ReadOnlySpan<char> trimChars)
         {
             for (; start < final; start++)
             {
-                for (var i = 0; i < trimChars.Length; i++)
-                    if (value.GetRawStringData(start) == trimChars[i])
+                var ch = value.GetRawStringData(start);
+
+                foreach (var trimChar in trimChars)
+                    if (ch == trimChar)
                         goto MATCHED;
 
                 break;
                 MATCHED: ;
             }
         }
 
-        return new StringView(value!, start, final - start, dummy: 0);
+        return new StringView(value!, start, final - start, unused: 0);
     }
 
     /// <summary>
@@ -348,7 +356,7 @@ public StringView TrimEnd()
                 if (!char.IsWhiteSpace(value.GetRawStringData(final)))
                     break;
 
-        return new StringView(value!, start, final + 1 - start, dummy: 0);
+        return new StringView(value!, start, final + 1 - start, unused: 0);
     }
 
     /// <summary>
@@ -369,7 +377,7 @@ public StringView TrimEnd(char trimChar)
                 if (value.GetRawStringData(final) != trimChar)
                     break;
 
-        return new StringView(value!, start, final + 1 - start, dummy: 0);
+        return new StringView(value!, start, final + 1 - start, unused: 0);
     }
 
     /// <summary>
@@ -398,7 +406,7 @@ public StringView TrimEnd(params char[]? trimChars) =>
     /// <returns>
     /// The trimmed <see cref="StringView"/>.
     /// </returns>
-    public StringView TrimEnd(ReadOnlySpan<char> trimChars)
+    public StringView TrimEnd(params ReadOnlySpan<char> trimChars)
     {
         if (trimChars.Length == 0)
             return TrimEnd();
@@ -411,16 +419,18 @@ public StringView TrimEnd(ReadOnlySpan<char> trimChars)
         {
             for (; final >= start; final--)
             {
-                for (var i = 0; i < trimChars.Length; i++)
-                    if (value.GetRawStringData(final) == trimChars[i])
+                var ch = value.GetRawStringData(final);
+
+                foreach (var trimChar in trimChars)
+                    if (ch == trimChar)
                         goto MATCHED;
 
                 break;
                 MATCHED: ;
             }
         }
 
-        return new StringView(value!, start, final + 1 - start, dummy: 0);
+        return new StringView(value!, start, final + 1 - start, unused: 0);
     }
 
     /// <summary>
@@ -446,7 +456,7 @@ public StringView Trim()
                     break;
         }
 
-        return new StringView(value!, start, final + 1 - start, dummy: 0);
+        return new StringView(value!, start, final + 1 - start, unused: 0);
     }
 
     /// <summary>
@@ -473,7 +483,7 @@ public StringView Trim(char trimChar)
                     break;
         }
 
-        return new StringView(value!, start, final + 1 - start, dummy: 0);
+        return new StringView(value!, start, final + 1 - start, unused: 0);
     }
 
     /// <summary>
@@ -502,7 +512,7 @@ public StringView Trim(params char[]? trimChars) =>
     /// <returns>
     /// The trimmed <see cref="StringView"/>.
     /// </returns>
-    public StringView Trim(ReadOnlySpan<char> trimChars)
+    public StringView Trim(params ReadOnlySpan<char> trimChars)
     {
         if (trimChars.Length == 0)
             return Trim();
@@ -515,8 +525,10 @@ public StringView Trim(ReadOnlySpan<char> trimChars)
         {
             for (; start <= final; start++)
             {
-                for (var i = 0; i < trimChars.Length; i++)
-                    if (value.GetRawStringData(start) == trimChars[i])
+                var ch = value.GetRawStringData(start);
+
+                foreach (var trimChar in trimChars)
+                    if (ch == trimChar)
                         goto MATCHED;
 
                 break;
@@ -525,16 +537,18 @@ public StringView Trim(ReadOnlySpan<char> trimChars)
 
             for (; final > start; final--)
             {
-                for (var i = 0; i < trimChars.Length; i++)
-                    if (value.GetRawStringData(final) == trimChars[i])
+                var ch = value.GetRawStringData(final);
+
+                foreach (var trimChar in trimChars)
+                    if (ch == trimChar)
                         goto MATCHED;
 
                 break;
                 MATCHED: ;
             }
         }
 
-        return new StringView(value!, start, final + 1 - start, dummy: 0);
+        return new StringView(value!, start, final + 1 - start, unused: 0);
     }
 
     /// <summary>
@@ -723,8 +737,8 @@ public override bool Equals([NotNullWhen(true)] object? obj)
         if (obj is null)
             return _length == 0;
 
-        if (obj is StringView)
-            return Equals(this, Unsafe.Unbox<StringView>(obj));
+        if (obj is StringView view)
+            return Equals(this, view);
 
         return obj is string s && Equals(s);
     }