Add StringSegment extensions and update version

Added `IsNullOrEmpty` and `IsNullOrWhiteSpace` methods to the
`TextExtensions` class for convenient null/empty/whitespace
checks on `StringSegment`. Improved code formatting in the
`removeEmpty` logic for readability. Bumped version in
`Open.Text.csproj` from 9.0.0 to 9.0.1 to reflect the changes.

Author: electricessence

Source/Extensions.StringSegment.cs

@@ -181,6 +181,27 @@ static IEnumerable<StringSegment> SplitAsSegmentsCoreOmitEmpty(
 		}
 	}
 
+	/// <summary>
+	/// Determines whether the specified <see cref="StringSegment"/> is null or empty.
+	/// </summary>
+	/// <remarks>This method is a convenience extension for checking whether a <see cref="StringSegment"/> has no
+	/// value or contains no characters.</remarks>
+	/// <param name="segment">The <see cref="StringSegment"/> to check.</param>
+	/// <returns><see langword="true"/> if the <paramref name="segment"/> is null or its length is zero; otherwise, <see
+	/// langword="false"/>.</returns>
+	public static bool IsNullOrEmpty(this StringSegment segment)
+		=> !segment.HasValue || segment.Length == 0;
+
+	/// <summary>
+	/// Determines whether the specified <see cref="StringSegment"/> is null, empty, or consists only of white-space
+	/// characters.
+	/// </summary>
+	/// <param name="segment">The <see cref="StringSegment"/> to evaluate.</param>
+	/// <returns><see langword="true"/> if the <paramref name="segment"/> is null, empty, or contains only white-space characters;
+	/// otherwise, <see langword="false"/>.</returns>
+	public static bool IsNullOrWhiteSpace(this StringSegment segment)
+		=> !segment.HasValue || segment.AsSpan().Trim().Length == 0;
+
 	/// <summary>
 	/// Enumerates a string by segments that are separated by the regular expression matches.
 	/// </summary>
@@ -236,10 +257,10 @@ static IEnumerable<StringSegment> SplitCore(string source, Regex pattern, String
 			}
 
 			int len;
-			if(removeEmpty)
+			if (removeEmpty)
 			{
 				len = source.Length - nextStart;
-				if(len==0) yield break;
+				if (len == 0) yield break;
 			}
 			else
 			{

Source/Open.Text.csproj

@@ -20,7 +20,7 @@
 		<RepositoryUrl>https://github.com/Open-NET-Libraries/Open.Text</RepositoryUrl>
 		<RepositoryType>git</RepositoryType>
 		<PackageTags>string, span, enum, readonlyspan, text, format, split, trim, equals, trimmed equals, first, last, preceding, following, stringbuilder, extensions, stringcomparable, spancomparable, stringsegment, splitassegment</PackageTags>
-		<Version>9.0.0</Version>
+		<Version>9.0.1</Version>
 		<PackageReleaseNotes></PackageReleaseNotes>
 		<PackageLicenseExpression>MIT</PackageLicenseExpression>
 		<PublishRepositoryUrl>true</PublishRepositoryUrl>