#351 Repl is slow when displaying lots of coloured output

Common/Product/ReplWindow/Repl/OutputBuffer.cs

@@ -17,6 +17,7 @@
 using System.Diagnostics;
 using System.Text;
 using System.Windows.Threading;
+using Microsoft.VisualStudio.Text;
 
 #if NTVS_FEATURE_INTERACTIVEWINDOW
 namespace Microsoft.NodejsTools.Repl {
@@ -241,11 +242,15 @@ internal sealed class OutputBuffer : IDisposable {
             }
 
             if (entries.Length > 0) {
-                for (int i = 0; i < entries.Length; i++) {
-                    var entry = entries[i];
-
-                    _window.AppendOutput(entry.Properties.Color, entry.Buffer.ToString(), i == entries.Length - 1);
+                var colors = new List<ColoredSpan>();
+                var text = new StringBuilder();
+                foreach (var entry in entries) {
+                    int start = text.Length;
+                    text.Append(entry.Buffer.ToString());
+                    colors.Add(new ColoredSpan(new Span(start, entry.Buffer.Length), entry.Properties.Color));
                 }
+                _window.AppendOutput(colors, text.ToString());
+
                 _window.TextView.Caret.EnsureVisible();
             }
         }

Common/Product/ReplWindow/Repl/ReplOutputClassifier.cs

@@ -54,6 +54,9 @@ class ReplOutputClassifier : IClassifier {
             if (startIndex < 0) {
                 startIndex = ~startIndex - 1;
             }
+            if (startIndex < 0) {
+                startIndex = 0;
+            }
 
             int spanEnd = span.End.Position;
             for (int i = startIndex; i < coloredSpans.Count && coloredSpans[i].Span.Start < spanEnd; i++) {

Common/Product/ReplWindow/Repl/ReplWindow.cs

@@ -2087,15 +2087,11 @@ private sealed class CommandFilter : IOleCommandTarget {
         }
 
         public void WriteOutput(object output) {
-            UIThread(() => {
-                Write(output);
-            });
+            Write(output);
         }
 
         public void WriteError(object output) {
-            UIThread(() => {
-                Write(output, error: true);
-            });
+            Write(output, error: true);
         }
 
         private void Write(object text, bool error = false) {
@@ -2110,7 +2106,7 @@ private sealed class CommandFilter : IOleCommandTarget {
         /// <summary>
         /// Appends text to the output buffer and updates projection buffer to include it.
         /// </summary>
-        internal void AppendOutput(ConsoleColor color, string text, bool lastOutput) {
+        internal void AppendOutput(IEnumerable<ColoredSpan> colors, string text) {
             int oldBufferLength = _outputBuffer.CurrentSnapshot.Length;
             int oldLineCount = _outputBuffer.CurrentSnapshot.LineCount;
 
@@ -2129,7 +2125,7 @@ private sealed class CommandFilter : IOleCommandTarget {
                 }
 
                 edit.Insert(oldBufferLength, text);
-                if (lastOutput && !_readingStdIn && !EndsWithLineBreak(text)) {
+                if (!_readingStdIn && !EndsWithLineBreak(text)) {
                     var lineBreak = GetLineBreak();
                     edit.Insert(oldBufferLength, lineBreak);
                     newOutputLength += lineBreak.Length;
@@ -2154,7 +2150,10 @@ private sealed class CommandFilter : IOleCommandTarget {
             );
 
             var outputSpan = new ReplSpan(trackingSpan, ReplSpanKind.Output);
-            _outputColors.Add(new ColoredSpan(span, color));
+            _outputColors.AddRange(colors.Select(cs => new ColoredSpan(
+                new Span(cs.Span.Start + oldBufferLength, cs.Span.Length),
+                cs.Color
+            )));
 
             bool appended = false;
 
@@ -2210,7 +2209,11 @@ private sealed class CommandFilter : IOleCommandTarget {
 
         private bool TryShowObject(object obj) {
             UIElement element = obj as UIElement;
-            if (element != null) {
+            if (element == null) {
+                return false;
+            }
+
+            UIThread(() => {
                 _buffer.Flush();
 
                 // figure out where we're inserting the image
@@ -2244,10 +2247,8 @@ private sealed class CommandFilter : IOleCommandTarget {
                 OnInlineAdornmentAdded();
                 WriteLine(String.Empty);
                 WriteLine(String.Empty);
-                return true;
-            }
-
-            return false;
+            });
+            return true;
         }
 
         private void OnAdornmentLoaded(object source, EventArgs e) {