Use ImmutableArray in SourceTextDiffer too

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/GeneratedDocumentPublisher.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Linq;
 using System.Threading;
@@ -62,7 +63,7 @@ internal sealed class GeneratedDocumentPublisher : IGeneratedDocumentPublisher,
             : new DocumentKey(ProjectKey.Unknown, filePath);
 
         PublishData? previouslyPublishedData;
-        IReadOnlyList<TextChange> textChanges;
+        ImmutableArray<TextChange> textChanges;
 
         lock (_publishedCSharpData)
         {
@@ -80,7 +81,7 @@ internal sealed class GeneratedDocumentPublisher : IGeneratedDocumentPublisher,
             }
 
             textChanges = SourceTextDiffer.GetMinimalTextChanges(previouslyPublishedData.SourceText, sourceText);
-            if (textChanges.Count == 0 && hostDocumentVersion == previouslyPublishedData.HostDocumentVersion)
+            if (textChanges.Length == 0 && hostDocumentVersion == previouslyPublishedData.HostDocumentVersion)
             {
                 // Source texts match along with host document versions. We've already published something that looks like this. No-op.
                 return;
@@ -89,7 +90,7 @@ internal sealed class GeneratedDocumentPublisher : IGeneratedDocumentPublisher,
             _logger.LogDebug(
                 $"Updating C# buffer of {filePath} for project {documentKey.ProjectKey} to correspond with host document " +
                 $"version {hostDocumentVersion}. {previouslyPublishedData.SourceText.Length} -> {sourceText.Length} = Change delta of " +
-                $"{sourceText.Length - previouslyPublishedData.SourceText.Length} via {textChanges.Count} text changes.");
+                $"{sourceText.Length - previouslyPublishedData.SourceText.Length} via {textChanges.Length} text changes.");
 
             _publishedCSharpData[documentKey] = new PublishData(sourceText, hostDocumentVersion);
         }
@@ -109,7 +110,7 @@ internal sealed class GeneratedDocumentPublisher : IGeneratedDocumentPublisher,
     public void PublishHtml(ProjectKey projectKey, string filePath, SourceText sourceText, int hostDocumentVersion)
     {
         PublishData? previouslyPublishedData;
-        IReadOnlyList<TextChange> textChanges;
+        ImmutableArray<TextChange> textChanges;
 
         lock (_publishedHtmlData)
         {
@@ -126,14 +127,14 @@ internal sealed class GeneratedDocumentPublisher : IGeneratedDocumentPublisher,
             }
 
             textChanges = SourceTextDiffer.GetMinimalTextChanges(previouslyPublishedData.SourceText, sourceText);
-            if (textChanges.Count == 0 && hostDocumentVersion == previouslyPublishedData.HostDocumentVersion)
+            if (textChanges.Length == 0 && hostDocumentVersion == previouslyPublishedData.HostDocumentVersion)
             {
                 // Source texts match along with host document versions. We've already published something that looks like this. No-op.
                 return;
             }
 
             _logger.LogDebug(
-                $"Updating HTML buffer of {filePath} to correspond with host document version {hostDocumentVersion}. {previouslyPublishedData.SourceText.Length} -> {sourceText.Length} = Change delta of {sourceText.Length - previouslyPublishedData.SourceText.Length} via {textChanges.Count} text changes.");
+                $"Updating HTML buffer of {filePath} to correspond with host document version {hostDocumentVersion}. {previouslyPublishedData.SourceText.Length} -> {sourceText.Length} = Change delta of {sourceText.Length - previouslyPublishedData.SourceText.Length} via {textChanges.Length} text changes.");
 
             _publishedHtmlData[filePath] = new PublishData(sourceText, hostDocumentVersion);
         }

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Extensions/SourceTextExtensions.cs

@@ -291,7 +291,7 @@ internal static class SourceTextExtensions
             return [];
         }
 
-        return SourceTextDiffer.GetMinimalTextChanges(text, originalTextWithChanges, DiffKind.Char).ToImmutableArray();
+        return SourceTextDiffer.GetMinimalTextChanges(text, originalTextWithChanges, DiffKind.Char);
     }
 
     /// <summary>

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/TextDifferencing/SourceTextDiffer.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Buffers;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Text;
@@ -63,12 +64,12 @@ internal abstract partial class SourceTextDiffer : TextDiffer, IDisposable
         }
     }
 
-    private IReadOnlyList<TextChange> ConsolidateEdits(List<DiffEdit> edits)
+    private ImmutableArray<TextChange> ConsolidateEdits(List<DiffEdit> edits)
     {
         // Scan through the list of edits and collapse them into a minimal set of TextChanges.
         // This method assumes that there are no overlapping changes and the changes are sorted.
 
-        var minimalChanges = new List<TextChange>();
+        using var minimalChanges = new PooledArrayBuilder<TextChange>(capacity: edits.Count);
 
         var start = 0;
         var end = 0;
@@ -99,28 +100,18 @@ internal abstract partial class SourceTextDiffer : TextDiffer, IDisposable
             minimalChanges.Add(new TextChange(TextSpan.FromBounds(start, end), builder.ToString()));
         }
 
-        return minimalChanges;
+        return minimalChanges.DrainToImmutable();
     }
 
-    public static IReadOnlyList<TextChange> GetMinimalTextChanges(SourceText oldText, SourceText newText, DiffKind kind = DiffKind.Line)
+    public static ImmutableArray<TextChange> GetMinimalTextChanges(SourceText oldText, SourceText newText, DiffKind kind = DiffKind.Line)
     {
-        if (oldText is null)
-        {
-            throw new ArgumentNullException(nameof(oldText));
-        }
-
-        if (newText is null)
-        {
-            throw new ArgumentNullException(nameof(newText));
-        }
-
         if (oldText.ContentEquals(newText))
         {
-            return Array.Empty<TextChange>();
+            return [];
         }
         else if (oldText.Length == 0 || newText.Length == 0)
         {
-            return newText.GetTextChanges(oldText);
+            return newText.GetTextChangesArray(oldText);
         }
 
         using SourceTextDiffer differ = kind == DiffKind.Line