Use pooled collections in a few more spots

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/CSharpFormatter.cs

@@ -38,12 +38,12 @@ internal sealed class CSharpFormatter(IDocumentMappingService documentMappingSer
 
     public static async Task<IReadOnlyDictionary<int, int>> GetCSharpIndentationAsync(
         FormattingContext context,
-        IReadOnlyCollection<int> projectedDocumentLocations,
+        HashSet<int> projectedDocumentLocations,
         CancellationToken cancellationToken)
     {
         // Sorting ensures we count the marker offsets correctly.
         // We also want to ensure there are no duplicates to avoid duplicate markers.
-        var filteredLocations = projectedDocumentLocations.Distinct().OrderBy(l => l).ToList();
+        var filteredLocations = projectedDocumentLocations.OrderAsArray();
 
         var indentations = await GetCSharpIndentationCoreAsync(context, filteredLocations, cancellationToken).ConfigureAwait(false);
         return indentations;
@@ -67,10 +67,10 @@ internal sealed class CSharpFormatter(IDocumentMappingService documentMappingSer
         return changes.ToImmutableArray();
     }
 
-    private static async Task<Dictionary<int, int>> GetCSharpIndentationCoreAsync(FormattingContext context, List<int> projectedDocumentLocations, CancellationToken cancellationToken)
+    private static async Task<Dictionary<int, int>> GetCSharpIndentationCoreAsync(FormattingContext context, ImmutableArray<int> projectedDocumentLocations, CancellationToken cancellationToken)
     {
         // No point calling the C# formatting if we won't be interested in any of its work anyway
-        if (projectedDocumentLocations.Count == 0)
+        if (projectedDocumentLocations.Length == 0)
         {
             return [];
         }

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/Passes/CSharpFormattingPass.cs

@@ -54,7 +54,7 @@ internal sealed class CSharpFormattingPass(
         cancellationToken.ThrowIfCancellationRequested();
 
         var indentationChanges = await AdjustIndentationAsync(changedContext, cancellationToken).ConfigureAwait(false);
-        if (indentationChanges.Count > 0)
+        if (indentationChanges.Length > 0)
         {
             // Apply the edits that modify indentation.
             changedText = changedText.WithChanges(indentationChanges);

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/Passes/CSharpFormattingPassBase.cs

@@ -12,6 +12,7 @@ using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.Components;
 using Microsoft.AspNetCore.Razor.Language.Extensions;
 using Microsoft.AspNetCore.Razor.Language.Syntax;
+using Microsoft.AspNetCore.Razor.PooledObjects;
 using Microsoft.CodeAnalysis.Razor.DocumentMapping;
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.VisualStudio.LanguageServer.Protocol;
@@ -28,7 +29,7 @@ internal abstract class CSharpFormattingPassBase(IDocumentMappingService documen
 
     public abstract Task<ImmutableArray<TextChange>> ExecuteAsync(FormattingContext context, ImmutableArray<TextChange> changes, CancellationToken cancellationToken);
 
-    protected async Task<List<TextChange>> AdjustIndentationAsync(FormattingContext context, CancellationToken cancellationToken, Range? range = null)
+    protected async Task<ImmutableArray<TextChange>> AdjustIndentationAsync(FormattingContext context, CancellationToken cancellationToken, Range? range = null)
     {
         // In this method, the goal is to make final adjustments to the indentation of each line.
         // We will take into account the following,
@@ -46,7 +47,7 @@ internal abstract class CSharpFormattingPassBase(IDocumentMappingService documen
         // Due to perf concerns, we only want to invoke the real C# formatter once.
         // So, let's collect all the significant locations that we want to obtain the CSharpDesiredIndentations for.
 
-        var significantLocations = new HashSet<int>();
+        using var _1 = HashSetPool<int>.GetPooledObject(out var significantLocations);
 
         // First, collect all the locations at the beginning and end of each source mapping.
         var sourceMappingMap = new Dictionary<int, int>();
@@ -276,7 +277,7 @@ internal abstract class CSharpFormattingPassBase(IDocumentMappingService documen
         }
 
         // Now that we have collected all the indentations for each line, let's convert them to text edits.
-        var changes = new List<TextChange>();
+        using var changes = new PooledArrayBuilder<TextChange>(capacity: newIndentations.Count);
         foreach (var item in newIndentations)
         {
             var line = item.Key;
@@ -289,7 +290,7 @@ internal abstract class CSharpFormattingPassBase(IDocumentMappingService documen
             changes.Add(new TextChange(spanToReplace, effectiveDesiredIndentation));
         }
 
-        return changes;
+        return changes.DrainToImmutable();
     }
 
     protected static bool ShouldFormat(FormattingContext context, TextSpan mappingSpan, bool allowImplicitStatements)

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/Passes/CSharpOnTypeFormattingPass.cs

@@ -181,7 +181,7 @@ internal sealed class CSharpOnTypeFormattingPass(
         Debug.Assert(cleanedText.IsValidPosition(rangeToAdjust.End), "Invalid range. This is unexpected.");
 
         var indentationChanges = await AdjustIndentationAsync(changedContext, cancellationToken, rangeToAdjust).ConfigureAwait(false);
-        if (indentationChanges.Count > 0)
+        if (indentationChanges.Length > 0)
         {
             // Apply the edits that modify indentation.
             cleanedText = cleanedText.WithChanges(indentationChanges);
@@ -277,13 +277,13 @@ internal sealed class CSharpOnTypeFormattingPass(
         return delta;
     }
 
-    private static List<TextChange> CleanupDocument(FormattingContext context, Range? range = null)
+    private static ImmutableArray<TextChange> CleanupDocument(FormattingContext context, Range? range = null)
     {
         var text = context.SourceText;
         range ??= text.GetRange(TextSpan.FromBounds(0, text.Length));
         var csharpDocument = context.CodeDocument.GetCSharpDocument();
 
-        var changes = new List<TextChange>();
+        using var changes = new PooledArrayBuilder<TextChange>();
         foreach (var mapping in csharpDocument.SourceMappings)
         {
             var mappingSpan = new TextSpan(mapping.OriginalSpan.AbsoluteIndex, mapping.OriginalSpan.Length);
@@ -294,15 +294,15 @@ internal sealed class CSharpOnTypeFormattingPass(
                 continue;
             }
 
-            CleanupSourceMappingStart(context, mappingRange, changes, out var newLineAdded);
+            CleanupSourceMappingStart(context, mappingRange, ref changes.AsRef(), out var newLineAdded);
 
-            CleanupSourceMappingEnd(context, mappingRange, changes, newLineAdded);
+            CleanupSourceMappingEnd(context, mappingRange, ref changes.AsRef(), newLineAdded);
         }
 
-        return changes;
+        return changes.ToImmutable();
     }
 
-    private static void CleanupSourceMappingStart(FormattingContext context, Range sourceMappingRange, List<TextChange> changes, out bool newLineAdded)
+    private static void CleanupSourceMappingStart(FormattingContext context, Range sourceMappingRange, ref PooledArrayBuilder<TextChange> changes, out bool newLineAdded)
     {
         newLineAdded = false;
 
@@ -425,7 +425,7 @@ internal sealed class CSharpOnTypeFormattingPass(
         return builder.ToString();
     }
 
-    private static void CleanupSourceMappingEnd(FormattingContext context, Range sourceMappingRange, List<TextChange> changes, bool newLineWasAddedAtStart)
+    private static void CleanupSourceMappingEnd(FormattingContext context, Range sourceMappingRange, ref PooledArrayBuilder<TextChange> changes, bool newLineWasAddedAtStart)
     {
         //
         // We look through every source mapping that intersects with the affected range and

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/Passes/HtmlFormattingPassBase.cs

@@ -8,6 +8,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.Syntax;
+using Microsoft.AspNetCore.Razor.PooledObjects;
 using Microsoft.CodeAnalysis.Razor.Logging;
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.VisualStudio.LanguageServer.Protocol;
@@ -37,7 +38,7 @@ internal abstract class HtmlFormattingPassBase(ILogger logger) : IFormattingPass
         }
 
         var indentationChanges = AdjustRazorIndentation(changedContext);
-        if (indentationChanges.Count > 0)
+        if (indentationChanges.Length > 0)
         {
             // Apply the edits that adjust indentation.
             changedText = changedText.WithChanges(indentationChanges);
@@ -49,15 +50,15 @@ internal abstract class HtmlFormattingPassBase(ILogger logger) : IFormattingPass
         return finalChanges.ToImmutableArray();
     }
 
-    private static List<TextChange> AdjustRazorIndentation(FormattingContext context)
+    private static ImmutableArray<TextChange> AdjustRazorIndentation(FormattingContext context)
     {
         // Assume HTML formatter has already run at this point and HTML is relatively indented correctly.
         // But HTML doesn't know about Razor blocks.
         // Our goal here is to indent each line according to the surrounding Razor blocks.
         var sourceText = context.SourceText;
-        var editsToApply = new List<TextChange>();
         var indentations = context.GetIndentations();
 
+        using var editsToApply = new PooledArrayBuilder<TextChange>(capacity: sourceText.Lines.Count);
         for (var i = 0; i < sourceText.Lines.Count; i++)
         {
             var line = sourceText.Lines[i];
@@ -163,7 +164,7 @@ internal abstract class HtmlFormattingPassBase(ILogger logger) : IFormattingPass
             }
         }
 
-        return editsToApply;
+        return editsToApply.DrainToImmutable();
     }
 
     private static bool IsPartOfHtmlTag(FormattingContext context, int position)