Ignore leading and trailing spaces in a fuzzy filter [patch]

TextFilter.Test/TextFilterTests.cs

@@ -1020,4 +1020,31 @@
 	{
 		Assert.IsFalse(TextFilter.IsMatch(text, "a*", TextFilterType.Regex, TextFilterMatchOptions.ByWordAll));
 	}
+
+	private static readonly string[] PaddingCandidates = ["hello world", "helium", "help", "yellow", "abcdef"];
+	private static readonly string[] HelMatches = ["hello world", "helium", "help"];
+
+	[TestMethod]
+	[DataRow("hel ")]
+	[DataRow(" hel")]
+	[DataRow("  hel\t")]
+	public void FuzzyIsMatchIgnoresFilterPadding(string paddedFilter)
+	{
+		foreach (string text in PaddingCandidates)
+		{
+			Assert.AreEqual(TextFilter.IsMatch(text, "hel", TextFilterType.Fuzzy), TextFilter.IsMatch(text, paddedFilter, TextFilterType.Fuzzy),
+				$"Padding in '{paddedFilter}' should not change whether '{text}' fuzzy-matches.");
+		}
+	}
+
+	[TestMethod]
+	[DataRow("hel ")]
+	[DataRow(" hel")]
+	public void FuzzyFilterIgnoresFilterPadding(string paddedFilter)
+	{
+		List<string> strings = ["hello world", "helium", "help", "yellow"];
+		List<string> result = [.. TextFilter.Filter(strings, paddedFilter, TextFilterType.Fuzzy)];
+		CollectionAssert.AreEquivalent(HelMatches, result,
+			$"Padding in '{paddedFilter}' should not hide items that 'hel' matches.");
+	}
 }

TextFilter/TextFilter.cs

@@ -124,7 +124,7 @@
 	private static readonly TimeSpan RegexMatchTimeout = TimeSpan.FromSeconds(1);
 
 	[System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "SYSLIB1045:Convert to 'GeneratedRegexAttribute'.", Justification = "Not available in older frameworks")]
 	private static Regex RegexMatchAnything() => new(".*", RegexOptions.Compiled);
 
 	/// <summary>
 	/// Gets a hint for the specified filter type.
@@ -240,7 +240,8 @@
 			{
 				TextFilterType.Glob => DoesMatchGlob(text, filter, textFilterMatchOptions, caseSensitivity),
 				TextFilterType.Regex => DoesMatchRegex(text, filter, textFilterMatchOptions, caseSensitivity),
-				TextFilterType.Fuzzy => Fuzzy.Contains(text.AsSpan(), filter.AsSpan(), out score),
+				// Padding would otherwise become a space the text must contain, so " hel" matched nothing.
+				TextFilterType.Fuzzy => Fuzzy.Contains(text.AsSpan(), filter.AsSpan().Trim(), out score),
 				_ => throw new NotImplementedException($"{nameof(TextFilterType)}.{filterType} has not been implemented"),
 			};
 	}
@@ -277,7 +278,7 @@
 
 			return ExcludedTokenPrefixes.Contains(prefix)
 				? TextFilterTokenType.Excluded
 				: RequiredTokenPrefixes.Contains(prefix)
 				? TextFilterTokenType.Required
 				: TextFilterTokenType.Optional;
 		})