Reduce Linq usage in FileSystemGlobbing (#98109)

* Reduce Linq usage in FileSystemGlobbing

Since GetResultsInFullPath uses a struct (FilePatternMatch) in a Linq call, this is causing extra disk space on native AOT'd applications because of struct specialization. Remove the Linq call and instead use a simple loop to create the result.

* Use ToArray instead of ToList to reduce unnecessary allocations.

---------

Co-authored-by: David Cantú <[email protected]>

Author: eerhardt

src/libraries/Microsoft.Extensions.FileSystemGlobbing/src/Internal/MatcherContext.cs

@@ -17,8 +17,8 @@ namespace Microsoft.Extensions.FileSystemGlobbing.Internal
     public class MatcherContext
     {
         private readonly DirectoryInfoBase _root;
-        private readonly List<IPatternContext> _includePatternContexts;
-        private readonly List<IPatternContext> _excludePatternContexts;
+        private readonly IPatternContext[] _includePatternContexts;
+        private readonly IPatternContext[] _excludePatternContexts;
         private readonly List<FilePatternMatch> _files;
 
         private readonly HashSet<string> _declaredLiteralFolderSegmentInString;
@@ -39,8 +39,8 @@ public MatcherContext(
             _files = new List<FilePatternMatch>();
             _comparisonType = comparison;
 
-            _includePatternContexts = includePatterns.Select(pattern => pattern.CreatePatternContextForInclude()).ToList();
-            _excludePatternContexts = excludePatterns.Select(pattern => pattern.CreatePatternContextForExclude()).ToList();
+            _includePatternContexts = includePatterns.Select(pattern => pattern.CreatePatternContextForInclude()).ToArray();
+            _excludePatternContexts = excludePatterns.Select(pattern => pattern.CreatePatternContextForExclude()).ToArray();
 
             _declaredLiteralFolderSegmentInString = new HashSet<string>(StringComparisonHelper.GetStringComparer(comparison));
         }
@@ -67,10 +67,11 @@ private void Match(DirectoryInfoBase directory, string? parentRelativePath)
             }
             else
             {
-                IEnumerable<DirectoryInfoBase> candidates = directory.EnumerateFileSystemInfos().OfType<DirectoryInfoBase>();
-                foreach (DirectoryInfoBase candidate in candidates)
+                IEnumerable<FileSystemInfoBase> candidates = directory.EnumerateFileSystemInfos();
+                foreach (FileSystemInfoBase candidate in candidates)
                 {
-                    if (_declaredLiteralFolderSegmentInString.Contains(candidate.Name))
+                    if (candidate is DirectoryInfoBase &&
+                        _declaredLiteralFolderSegmentInString.Contains(candidate.Name))
                     {
                         entities.Add(candidate);
                     }

src/libraries/Microsoft.Extensions.FileSystemGlobbing/src/MatcherExtensions.cs

@@ -2,9 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using Microsoft.Extensions.FileSystemGlobbing.Abstractions;
 
 namespace Microsoft.Extensions.FileSystemGlobbing
@@ -51,9 +51,18 @@ public static void AddIncludePatterns(this Matcher matcher, params IEnumerable<s
         /// <returns>Absolute file paths of all files matched. Empty enumerable if no files matched given patterns.</returns>
         public static IEnumerable<string> GetResultsInFullPath(this Matcher matcher, string directoryPath)
         {
-            IEnumerable<FilePatternMatch> matches = matcher.Execute(new DirectoryInfoWrapper(new DirectoryInfo(directoryPath))).Files;
-            string[] result = matches.Select(match => Path.GetFullPath(Path.Combine(directoryPath, match.Path))).ToArray();
+            PatternMatchingResult patternMatchingResult = matcher.Execute(new DirectoryInfoWrapper(new DirectoryInfo(directoryPath)));
+            if (!patternMatchingResult.HasMatches)
+            {
+                return Array.Empty<string>();
+            }
 
+            IEnumerable<FilePatternMatch> matches = patternMatchingResult.Files;
+            List<string> result = matches is ICollection matchCollection ? new(matchCollection.Count) : new();
+            foreach (FilePatternMatch match in matches)
+            {
+                result.Add(Path.GetFullPath(Path.Combine(directoryPath, match.Path)));
+            }
             return result;
         }