Improved testing.

Author: electricessence

Source/Extensions.Equals.cs

@@ -0,0 +1,127 @@
+using System;
+
+namespace Open.Text
+{
+	public static partial class Extensions
+	{
+
+		/// <summary>
+		/// Optimized equals for comparing as span vs a string.
+		/// </summary>
+		/// <param name="source">The source span.</param>
+		/// <param name="other">The string to compare to.</param>
+		/// <param name="stringComparison">The string comparison type.</param>
+		/// <returns>True if the are contents equal.</returns>
+		public static bool Equals(this in ReadOnlySpan<char> source, string? other, StringComparison stringComparison)
+		{
+			if (other is null) return false;
+			var len = source.Length;
+			if (len != other.Length) return false;
+			return len switch
+			{
+				0 => true,
+				1 when stringComparison == StringComparison.Ordinal => source[0] == other[0],
+				_ => source.Equals(other.AsSpan(), stringComparison),
+			};
+		}
+
+		/// <summary>
+		/// Optimized equals for comparing as span vs a string.
+		/// </summary>
+		/// <param name="source">The source span.</param>
+		/// <param name="other">The string to compare to.</param>
+		/// <param name="stringComparison">The string comparison type.</param>
+		/// <returns>True if the are contents equal.</returns>
+		public static bool Equals(this in Span<char> source, string? other, StringComparison stringComparison)
+		{
+			if (other is null) return false;
+			var len = source.Length;
+			if (len != other.Length) return false;
+			return len switch
+			{
+				0 => true,
+				1 when stringComparison == StringComparison.Ordinal => source[0] == other[0],
+				_ => MemoryExtensions.Equals(source, other.AsSpan(), stringComparison)
+			};
+		}
+
+		/// <summary>
+		/// Optimized equals for comparing spans.
+		/// </summary>
+		/// <param name="source">The source span.</param>
+		/// <param name="other">The span to compare to.</param>
+		/// <param name="stringComparison">The string comparison type.</param>
+		/// <returns>True if the are contents equal.</returns>
+		public static bool Equals(this in Span<char> source, in Span<char> other, StringComparison stringComparison)
+		{
+			var len = source.Length;
+			if (len != other.Length) return false;
+			return len switch
+			{
+				0 => true,
+				1 when stringComparison == StringComparison.Ordinal => source[0] == other[0],
+				_ => MemoryExtensions.Equals(source, other, stringComparison)
+			};
+		}
+
+		/// <summary>
+		/// Optimized equals for comparing spans.
+		/// </summary>
+		/// <param name="source">The source span.</param>
+		/// <param name="other">The span to compare to.</param>
+		/// <param name="stringComparison">The string comparison type.</param>
+		/// <returns>True if the are contents equal.</returns>
+		public static bool Equals(this in Span<char> source, in ReadOnlySpan<char> other, StringComparison stringComparison)
+		{
+			var len = source.Length;
+			if (len != other.Length) return false;
+			return len switch
+			{
+				0 => true,
+				1 when stringComparison == StringComparison.Ordinal => source[0] == other[0],
+				_ => MemoryExtensions.Equals(source, other, stringComparison)
+			};
+		}
+
+		/// <summary>
+		/// Optimized equals for comparing as string to a span.
+		/// </summary>
+		/// <param name="source">The source string.</param>
+		/// <param name="other">The span to compare to.</param>
+		/// <param name="stringComparison">The string comparison type.</param>
+		/// <returns>True if the are contents equal.</returns>
+		public static bool Equals(this string source, in ReadOnlySpan<char> other, StringComparison stringComparison)
+		{
+			if (source is null)
+				throw new ArgumentNullException(nameof(source));
+			var len = source.Length;
+			if (len != other.Length) return false;
+			return len switch
+			{
+				0 => true,
+				1 when stringComparison == StringComparison.Ordinal => source[0] == other[0],
+				_ => source.AsSpan().Equals(other, stringComparison),
+			};
+		}
+
+		/// <summary>
+		/// Optimized equals for comparing as string to a span.
+		/// </summary>
+		/// <param name="source">The source string.</param>
+		/// <param name="other">The span to compare to.</param>
+		/// <param name="stringComparison">The string comparison type.</param>
+		/// <returns>True if the are contents equal.</returns>
+		public static bool Equals(this string source, in Span<char> other, StringComparison stringComparison)
+		{
+			if (source is null) throw new ArgumentNullException(nameof(source));
+			var len = source.Length;
+			if (len != other.Length) return false;
+			return len switch
+			{
+				0 => true,
+				1 when stringComparison == StringComparison.Ordinal => source[0] == other[0],
+				_ => source.AsSpan().Equals(other, stringComparison),
+			};
+		}
+	}
+}